fprdi ournal

fd.

Volume J8Nos. l-4

FPRDI "OURnAL

ISSN 011 5-0456 January-December 1989

FPRDI "OURftAL

A PUBLICATION FOR FOREST PRODUCTS RESEARCH AND DEVELOPMENT INDUSTRIES

I llllllll lllll llll Ill llllll lllll llll llllll lllll lllll lllll 11111111 STI-04-7625

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FPRDI JOURNAL

Volume 18 Nos. 1-4 January-December 1989

Entered as Second Class Matter on 21 November 1984 at the College Post Office, Laguna 4031, Philippines.

The FPRDI Journal projects the research and industries development efforts of the Forest Products Research and Development Institute (FPRDI).

TABLE OF CONTENTS

Composition analysis of ipil-ipil [Leucaena leucocephala 4 (Lam.) de Wit] seed gum o Buena S. Pamplona and Dr. Jose V. Zerrudo

Development of oil finish from castor (Ricinus communis L.) 15 seeds o Yolanda L. Tavita and Adelina E. Manas

Properties of some Philippine erect palms 30 o Zenita B. Espiloy, Mario M. Maruzzo, Mariluz SP. Dionglay

and Marina A. Alipon

Machining and jointing properties of woodwool cement boards 46 o Grecelda A. Eusebio, Antonio A. Salita Jr. and

Julian 0. Roxas

Variation in bending strength properties of glued-laminated 62 coconut wood o Felix B. Tamolang

Bending quality improvement of solid bentwood stocks for 78 furniture components o Robert A. Natividad

Effects of moisture content and monomer mixtures on the 89 polymerization of kaatoan bangkal [Anthocephalus chinensis (Lam.) Rich. ex Walp.], malakauayan (Podocarpus rumphii Blume) and white lauan (Shorea contorta Yid.) for tool handles o Josephine P. Carandang

4

COMPOSITION ANALYSIS OF IPIL-IPIL (Leucaena leucocephala (Lam.) de Wit) SEED GUM .

Buena S. Pamplona and Dr. Jose V. Zerrudo 1

ABSTRACT

The chemical composition of the water-soluble component of ipil-ipil [K-28, Cunningham and native (Copil No. 2) varieties] seeds was studied. The gum content was analyzed for its composition, viscosity and IR spectra.

On the average, the fat-free seeds yielded 35.0% hot water-soluble matter which contained 22.5% total sugars, 19.2% proteins, 0.33% tannin and 14.9% ethanolprecipitated gum.

PC and HPLC analyses showed the presence of mannose and galactose in a molar ratid of 1.3:1.0 (man:gal) in the acid hydrolyzate of the gum. The gum isolate had an intrinsic viscosity of 7.7 dL/ g. A 1,000 ppm aqueous solution exhibited a 2.29 cp viscosity.

The IR spectra of the gum were similar to those of authentic Lucerne (Medicago sativa) galactomannan, especially in the fingerprint region. ·

INTRODUCTION

Giant ipil-ipil trees abound in the Philippines. Fast-growing and profific seeders, they have multiple uses. A hectare of land planted to 2,500 ipilipil trees can yield 2.5 tons seeds per year (IPB 1983). Higher value products may be derived from the seeds if their composition and properties are known.

While extensive studies on locallygrown Leucaena sp. are being undertaken to enhance its utiliz.ation as sources of forage and fuel wood, no research has been reported on the c,hemical investigation or ipil-ipil seeds for industrial application.

Like seeds of legume plant-sources of commercial gums such as guar (Cyamopsis tetragonolobus) and locust bean (Ceratonia siliqua), Leucaena seeds contain considerable amounts of heteropolysaccharide identified as galactomannan (GM).

• Objective

To identify the components of the water-soluble matter on seeds of locally-grown ipil-ipil trees, especially the gum content.

1 Senior Science Research Specialist, FPRDI, College, Laguna 4031 and Professor, Department of Wood Science and Technology, UPLB-CF, College, Laguna 4031 respectively.

Review of Literature

A non .. starch, viscous, water-soluble heteropolysaccharide more popularly called gum or .mucilage is present in many legume seeds, including Leucaena seeds. It is chemically known as GM (Anderson 1949, Andrews et al. 1952, Hylin and Sawai 1964, McCleary and Matheson 197 4, 197 5). Gums are usually observed as thickenings of the endosperm cell walls and function as reserve food for the germinating plant.

In ipil-ipil seeds, the gum is probably concentrated in the translucent, yellowish-brown, thin layer between the seed coat and the cotyledon and diffused throughout the soft cotyledon (Morimoto et al. 1962).

Morimoto isolated 25% gum from L. glauca by repeated precipitation with ethanol. The gum was composed of 50% mannose and 42% galactose. A 0.1 % solution of the gum exhibited higher viscosity than the same concentration of gum arabic and gum tragacanth. Unrau (1961) identified 57% mannose and 43% galactose from the seed gum of L. glauca. McCleary· (1974, 1975, 1979, 1983) made significant contributions in the elucidation of structures and properties of GM of many legume seeds like guar, locust bean, lucerne, L. leucocephala, among others, by collecting and identifying various fractions of the molecules hydrolyzed by suitable enzymes.

MATERIALS AND METHODS

Seed Materials

UPLB certified ipil-ipil seeds of giant K-28, hybrid, giant x Peruvian (Cunningham) and native variety (Copil No. 2).

5

Methods

Sample Preparation

Organic solvent extraction. Seeds of known chemical composition (Pamplona 1986) were ground to 16-mesh tyler sieve, and successively extracted with petroleum ether for 6 hr and 95% ethanol for 10 hr in a Soxhlet extractor. The residue (1) was kept for subsequent use.

Crude Gum Extraction

Water extraction. Triplicated sample of residue {l) was contained in a cotton bag about 8 cm in diameter and subjected to five times repeated extraction with fresh water at 40 ± 2°c for 10 hr. The viscous extract (2) was centrifuged at 4,000 rpm for 5 min to remove the remaining water-insoluble matter.

Analyses of the Aqueous Extract

Qualitative tests. Analyses were done ior reducing sugars, polyphenols, lignin, starch and protein.

Quantitative tests. Analyses were done for total sugars by the Anthrone method (Koehler 1952) an'1 phenolsulfuric acid method (Dubois et al. 1956), oxidized tannins by the FolllnDenis method (Burns 1963) and water'soluble proteins by the Lowry method (Lowry et al. 1951).

Gum Isolation

Precipitation and purification. A 40-ml aliquot of the aqueous extract was treated with 50% ethanol, AR, giving a mixed white and cream, flaky and stringy gum predpitate. The gum was centrifuged and impurities removed by discarding the supernatant and washing the gum precipitate with fresh 500/o ethanol while inside the centrifuge tube. The gum was redissolved in

6

water and the whole cycle of precipi ta ti on, cen trif uga tion, washing, dissolution and precipitation was done three times.

Gum Analysis

Paper chromatography (PC). The gum was hydrolyzed with sulfuric acid. Except for the · reaction. time, the methods used by Selvendran (1979) were applied.

The acid hydrolyzate of the gum, standard mixture of monosaccharides and galacturonic acid and each of the individual sugar standards were separately spotted in Whatman No. 2 filter paper, with 25~ 72 drops from a capillary tube constituting each spot of the hydrolyzate. The chromatographs were developed by descending technique with butanol-ethanol-water (BuOH:EtOH:H20, 4:1:1 v/v/v) as the solvent system. The papers were removed from the tank after 16 hr irrigation and dried. The Rf values of t-he standard sugars were determined from one paper. The rest of the papers were put back· in the chromatocab. The process of irrigating-drying was repeated five times on the san:e paper. Total running time was 62 hr. Spray reagent was 0.5% paraanisidine hydrochloride. Color was developed after 1 O· min exposure in an oven at 130°C. The spots were viewed under UV light and identified by comparing their relative positions with the spots of the· sugar standards.

High-pressure liquid chromatograohy (HPLC). A 1.24% unhydrolyzed gum, 0-5000 ppm each of · the standard monosaccharides, and a solution of the hydrolyzed gum each in 75% acetonitrile (Fluka, 99.5% purity) were individually run in a Toyo Soda HLC 803C model of HPLC using an amineimpregnated, silica-based column (IS-450 NH2, 4 mm internal diameter x 300 mm length) and a differential

refractometer (RI-8) detector. The flow rate w~s 0.8 ml/min at a pressure of 50 kg/cm .

Comparison of the retention times of the sug·ars in the hydrolyzate with the standards and spiking technique was done to identify the gum components.

The corrected peak areas of the identified sugars in the hydrolyzate were plotted in the standard curves to quantify the sugar components.

Viscosity. The absolute viscosities of 50-1500 ug/ml range of gum concentrations were determined using an Ostwald-Fenske viscometer No. 150.

Specific viscosity, N.SP' and intrinsic viscosity were determmed.

Protein impurity. The residual proteins in the gum isolate were analyzed by the Lowry colorimetric method. Bovine albumin solutions of 0 to 10 ug/ml range of concentration were used to plot the standard curve.

Infra-red (JR). The infra-red spectra . of the ethanol-precipitated gum, along with authentic galactomannan sample from Lucerne seeds

1 were read at 400

cm - l to 4000 cm· frequency range using Per kin Elmer 735B spectropho'tometer and potassium bromide pellet as blank.

RESULTS AND DISCUSSIONS

Sample Preparation

The 4.6% petroleum ether-soluble and the 8.8% ethanol-soluble matter were removed from the sample used to extract the gum.

Petroleum ether could have removed lipids, waxes and non-polar pigments, while the 95% ethanol could, have dissolved much of the low-molecular

weight, polar and charged molecules like the simple sugars and some oligosaccharides, phenolics, other

. pigments, among others.

Crude Gum Extraction

The water-soluble components of ipilipil seeds ranged from 32.6% to 40. 7%, averaging 36.5%, 34.9% and 33. 7% for K-28, Cunningham and Copil No. 2, respectively. ·

Analysis of the Aqueous Extract

• Qualitative tests

The chemical tests done on the samples to detect the presence of reducing sugars, polyphenols, lignin, starch and proteins are summarized in Table 1. Results indicated the presence of reducing sugars, polyphenol's and proteins. Coniferyl aldehyde and amylose were not detected.

High molecular weight carbohydrate materials and phenolics, water-soluble proteins and their reaction products, and other water-soluble matter go with

7

the aqueous extract of the seeds. Many plant seeds like those belonging to the Leguminoceae family are reported to have heteropolysaccharides, instead of starches, as the major carbohydrate reserves present (Meier and Reid 1982). Phenolics in the . form of fla vone or fla vonal compounds were identified by Borja (1981) in the yellow pigment of the aqueous extract of ipil-ipil seeds. The water-soluble albumins were isolated from ipil-ipil seeds by Espiritu (1977).

• Quantitative tests

Total sugars. The reaction of the sugars having free or potentially free reducing ends with concentrated sulfuric acid yields furf ural or furan derivatives due to dehydration in the c2 and c3 positions in the sugar monomers. The furan compound then forms a colored complex with a

. coloring reagent like phenol or anthrone. The ease of formation of the furfural derivatives determines the rate of development of the color intensity. The total sugars will include the water-soluble gum component of the seeds.

Table 1. Chemical tests for reducing sugars, polyphenols, lignin,, starch and proteins in the aqueous extract of K-28 seeds

TEST REAGENT COLORATION INTERPRETATION

Fehling's solution rust red reducing sugars may be present precipitate

1 % Ferric chloride deep blue polyphenols may be .present 1 O/o Potassium

f erricyanate 1 % phloroglucinol light yellow conif eryl aldehyde may be absent

in 120/o hydrochloric acid

Iodine in potassium light yellow amylose may be absent iodide

Biuret reagent pink violet proteins may be present

8

Using the Anthrone method, . total sugars in the extract were best approximated in the maximum green color intensity at 615 nm wavelength. The average ·total sugars was· 22.58% · using mannose as standard.

The phenol-sulfuric acid method checked the values obtained using the Anthrone reagent. The maximum absorbance for the yellow-orange color both for the sample and the glucose standard was at 485 nm wavelength. Avei:age percentage total sugars was 22.380/o based on glucose as standard.

Oxidized tannins. Phosphotungsticphosphomolybdic compound, the active component of the Folin-Denis reagent, is reduced by the phenolic groups in acid solution. The reduced salt gives a stable blue color with sodium carbonate (Folin and Denis 1912, Smith et al. 1955).

The crude extract contained 0.330/o average tannin materials as tannic acid equivalent.

Water-soluble proteins. The Lowry method of colorimetric analysis for proteins in solution involved the formation of a blue color through the reaction of protein with copper in alkali, as in the Biuret reaction, followed by the reduction of the phosphomolybdic-phosphotungstic reagent ·by the copper-treated protein.

The crude aqueous extracts contained 19.20/o average protein based on bovine albumin standard. Espiritu (1977) identified globulins, albumins, prolamines and glutelins as the proteins present in ipil-ipil seeds. Of these, only albumins are water-soluble.

Gum Isolation

Gum precipitation. was found to be within the concentration range of 300/o to 60% ethanol. Using higher than 600/o

ethanol resulted in a· gum precipitate that was distinctly yellow. The purified gum was a mixture of white and cream-colored, flaky and stringy precipitate.

The gum isolated from the aqueous extracts of the three varieties of ipilipil seeds ranged from 12.8% to 17.9%, with averages of 16.4%, 14.7% and 13.5% for K-28, Cunningham and Copil No. 2 respectively.

Gum Analysis·

Acid hydrolysis. Brownish to black solutions resulted after treatments of the purified gum samples with sulfuric acid. Upon centrifugation and filtration of the neutralized solution, colorless hydrolyzate was recovered. The partially-dried hydrolyzates appeared cream-colored.

PC. Only mannose and galactose were detected, the former appearing in a more in tense and bigger yellow spot under UV light than the latter. No other sugars appeared in the paper chromatogram of the acid-hydrolyzed sample in Figure 1.

The results suggested the presence of a larger amount of mannose compared to galactose. No galactouronic acid was detected.

HPLC. Analysis of the unhydrolyzed ethanol-precipitated gum by HPLC showed the absence of monosaccharide or any other molecule soluble in 75% acetonitrile which could be detected by the instrument.

Two prominent peaks were read from the chromatogram of the gum hydrolyzate which corresponded to mannose and galactose having retention times of 10.7 and 11.9 respectively (Fig. 2). Separate spikings with the standard mannose and galactose solutions confirmed the identities of the sugars (Figs. 3 and 4). A trace amount of an

unidentified sugar might be present whose retention time might correspond to ara binose.

Known concentrations of mannose and galactose solutions were used as Standards to quantify the sugars present in the gum hydrolyzates.

HPL chromatograms of the different hydrolyzates prepared from the· various conditions of acid hydrolysis of the gum gave an average mass or molar ratio of 1.3:1.0 (mannose:galactose) (Table 2).

HPLC and , PC analyses both proved mannose and galactose as the component sugars. HPLC showed a molar ratio (man:gal) of 1.3:1.

Viscosity. The aqueous solution of ipil-ipil gum was viscous. A comparison was made with known data on guar gum viscosities (Table 3).

Viscosities of ipil-ipil gum sample at 30°.C after 45 hr hydration at 4°c were close to known viscosities of the same concentration of guar .gum at 21°c after 24 hr hydration at the same temperature. Unrau (1961) reported a vis.cosi ty value of 2.52 cp for a 1,000 ppm L. leucoce phala · galactomannan (DP=l50) solution at 20°c.

9

The intrinsic viscosity of ipil-ipil (K-28) gum isolate was 7.67 dL/g (Fig. 5).

Protein impurity. An average of 2.1 % residual protein materials· in the gum isolate was detected using bovine albumin as standard.

IR. The IR spectra of the gums are shoyn in Figures 6 and 7. At 3400 cm· to 3100 cm·1, frequency range was broad and had a strong peak characteristic of the hydrogen-bonded OH stretch as in alcohol in polymeric assofiation. The strong peak at 2850 cm· indicated the saturated C-H stretch.

1 At the freqpency range of

1160 cm· to 1,000 cm - the peaks were broad and strong, indicative of the overlapping peaks of the -OH bond for primary and secondary alcohols, the CO stretch for alcohols and the C-0-C stretch for ether. These were complemep ted by peaks close to the 1350 cm· frequency. Cerezo (19651 identified thy clean peaks at 890 cm· and 820 cm· as characteristics of the beta-linked mannopyranose and the alpha-linked galactopyranose residues, respectively.

All the functionalities shown in the IR analysis indicated the presence of polyhydric alcohols linked together with ether bonding a·nd contained

Table 2. Mannose and galactose released by the different hydrolytic procedures

SULFURIC ACID

2N 2N 72%; 2N

HEATING PERIOD

(hr)

2 3 3

SUGARS RECOVERED Man.nose ug/mg sample

510.1 598.2 652.4

Ga lactose ug/mg sample

376.3 456.8 537.8

(Ave.)

Molar ratio Man Gal

1.36 1.31 1.21 i'.3

1 1 I 1

10

GAL.AC'NRONIC ACID

GA~TOSE GL CSE

MANNO SE

ARABI NOSE

XY\.OSE

i I - 2 Ill z

!It ... 0

I I ii ~ i111 I I

n~! 1 n n8 ~ ~.. z ~i :I '4 ~ -o-o-(1..--.(,--.")- - - -~--~-

0 0

0 0 8 0

D 0 0

1' ~

0 ~

Figure 1. Paper chromatogram of the acid hydrolyzate of the gums. Solvent system: 1-butanol-ethanolwater (4:1:1 v/v/v),· Spray reagent: para-anisidine hydrochloride.

23mlnuto1

1u•11JnlY1Gte sa•ple Injected

Figure 3. HPL chromatograms of B. ipilipil (k~28) gum ·hydrolyzate samqle solution; D. mannose•spiked gum hydrolyzate sample. Peak (retention time in min): a - galactose (11.9 ), b -mannose ( 10.7 ), c and d - unidentified, e - solvent, 75% acetonitrile in water.

e

.... hydrolpa19 sample Injected

J

21 mlnute1

Figure 2. HPL chromatograms of A. mixture of galactOStf and mannose standards,· B. ipil-ipil ( K-28) gum hydrolyzate sampl~ solution. Peak (retention time in min): a - galactose ( 11.9 ), b - mannose (10.7 ), c and d -unidentified, e - solvent, 75% acetonitrile in water.

• b

a

oum hydrolyzcite 1amp1t Injected

Figure 4. HPL chromatograms of B. ipilipil (K-28) gum hydrolyzate sample solution,· C. galactose-spiked gum hydrolyzate sample. Peak (retention time in min): a - galactose ( 11.9 ), b -mannose ( 10.7 ), c and d - unidentified, e - solvent, 75% acetonitrile in water.

11

Table 3. Viscosity values of ipil-ipil and guar gums

CONCENTRATION (ppm)

0 100 300 500

1,000 l,500 2,000

IPIL-IPIL GUM VISCOSITY

(cp)

0.8007 0.966 1.148 1.374 2.286 3.481 5.547

GUAR GUM VISCOSITYa

(cp)

0.995

1.557

a Reported by Whistler (1973) using Ostwalds tubes No. 100 and 400 at 27°C.

. 25.0

~u

20.0

15.0

10.0

7.7

0.0

0 2 4 8 12 us 20

CONCENTRATION, c(.I.) . ell

Figure 5. Intrinsic viscosity determination for the ipil-ipil (K-28) seed gum.

reducing groups. An extensive hydrogen bonding such as those present in polysaccharide molecules in polymeric association was strongly indicated. Most especially in the fingerprint region, the IR spectra of the ipil-ipil gums were very similar to those of authentic galactomannan isolated from lucerne (Fig. 6), who~e structure had been elucidated .by Hirst et al. (1947) and Andrews et al. (1952).

CONCLUSIONS

lpil-ipil gum with yields ranglng from 13% to 19% based on the ovendry weight of ground ipil-ipil seeds can be isolated by water extraction followed by repeated precipitation with 50% ethanol. It contains minimal protein impurity.

The IR spectra of the gum are similar to those of the Lucerne seed galactomannan.

. Only mannose and galactose are detected in the gum using the PC and HPLC techniques. HPLC shows a molar ratio (man:gal) of 1.3:1.0.

12

~ I I .. ... 40

50

20

r-· ... A I --~ I '

' i I ! I I . :

t\ I

:i I i \: I V ! I

' I I I :. t ~ : . .: ' I I I

\ ' ... '·•

MICROMETERS (11111)

Letend:

- - - Lucerne tolootcllftOnnan

- lpll·lpll (K·H) 111111

~· . 5200 2800 2400 2000 l900 I 1700 1100 IOOO 1400 1500 I FREQUENCY (cm • 1)

1100 IOOO toO 800 700 ~ 500 400

Figure 6. IR spectra of the gums: A. Lucerne galactomannan,· B. ipil-ipil ( K-28) gum.

MICROt.tETER9 . ~m)

4000 HOO !200 2800 2400 2000 II 1900 1400 'REQUENCY ( cM-t)

11!00 IOOO IOO

Figure 7. IR spectra of the gums isolated from ipil-ipil seeds: A. -- Copil,· B. --- K-28,· C •... Cunningham

eoo 400

. The intrinsic viscosity of the gum is 7.67 dL/g. The aqueous solution of the gum is viscous; a 1000 ppm exhibits a viscosity of 2.29 cp at 30°c after 45 hr hydration at 4°C.

RECOMMENDATIONS

. Conduct composition and structural studies, physical and chemical

REFERENCES

13

modifications of the gum isolated by other techniques.

. Explore possibilities of the industrial appiication of the gum a~ paper, food and drug additives.

. Study further the seed residue a(ter gum extraction for possible use as feed component.

ANDERSON, E. 1949. Endosperm mucilages of legume-occurrence and composition. Ind. and Eng'g Chem. 41:1987-2890.

ANDREWS, P., L. HOUGH and J.K.N. JONES. 1952. Mannose-containing polysaccharides. I. The galactomannan of lucerne and clover seeds. J. Am. Chem. Soc. 7 4:4029-4032.

BORJA, M P. 1981. Extraction and analysis of the water-soluble pigments of Leucaena leucocephala (ipil-ipil) seeds. BS thesis abstract. Res. Bull. No. 2. Dept. of Chem., UP Diliman, Q.C. 15-16.

BURNS, R.E. 1963. Folin-Denis method of tannin analysis. Agric. Exptl. Stn. Tech. Bull. 32:1-14.

CEREZO, A.S. 1965. The constitution of a galactomannan from the seeds of Gleditsia amorphoides. J. Org. Chem. 30:924-927.

DUBOIS, MK. GILLES, J.K. HAMILTON, P.A. REBERS, and F. SMITH. 1966. Calorimetric method for determination of sugars and related substances. Anal. Chem. 28:350-356.

ESPIRITU, J. 1977. Studies of ipil-ipil seed proteins~ BS thesis. UPLB, College, Laguna.

HIRST, E.L. and J.K.N. JONES. 1948. The galactomannans of carob-seed gums (Gum Gatto). J. Chem. Soc. 1278-1282.

HYLIN, J.W. and K. SAWAI. 1964. The enzymatic hydrolysis of Leucaena glauca galactomannan. J. Biol. Chem. 239:990-992.

KOEHLER, L.H. 1952. Differentiation of carbohydrates by anthrone reaction rate and color intensity. Anal. Chem. 24:1576-1579.

LOWRY, O.H., N.J. ROSEBROUGH, A. L. FARR and R.J. RANDALL. 10' 1

Protein measurement with the Folin Phenol Reagent. J. Biol. Chem. b-':.lo::>-275.

14

MCCLEARY, B.V. 1979. Enzymic hydrolysis, fine structure and gellling interaction of legume-seed D-galacto•D-mannans. Carbohyd. Res. 71:705-230."

------- and N .K .. MA. Tl:JESON. 197 5. Galactomannan structure and beta-mannanase and beta-mannosidase activity in germinating legume seeds. Phytochem. 14:1187-1194.

1974. Alpha-D-galactosidase activity and galactomannan and galactosyl sucrose oligosaccharide depletion in germinating legume seeds. Phytochem. 13:1747-1757.

and E. NURTHERN, F.R. TARAYEL and J.P. JOSELAEAU. -------1983. Characterization of the oligosaccharides produced on hydrolysis of galactomannan with beta-0-mannanase. Carbohyd. Res. 118-91-109.

MEIR, H. and J.S.G. REID. 1982. Reserve polysaccharides other than starch in higher plants. In. Plant carbohydrates. I. Intracellular carbohydrates. F.A. Loewus and W. Tanner (eds.). Springer-Verleg, Berlin, Heidelberg, N.Y. 418-429. .

MORIMOTO, J.Y., I.C.J. UNRAU and A.M. UNRAU. 1962. Chemical and physical properties and the enzymatic degradation of some tropical plant gums. Agr. Food Chem. 10:134-137.

PAMPLONA, B.S. 1986. Some properties and use of ipil-ipil [Leucaena leucocephala (Lam.) de Wit] seed gum. Unpubl. MS Thesis, UPLB.

UNRAU, A.M. 1961. The constitution of galactomannan from the seeds of Leucaena glauca. J. Org. Chem. 26:3097-3101.

SELVENDRAN, R.R., J.F. MARCH and S.G. RING. 1979. Determination of aldoses and uronic acid content of vegetable fiber. Anal. Biochem. 96:282-292.

WHISTLER, R.L. (ed.). 1973. Industrial gums, polysaccharides and their derivatives. Acad. Press. N.Y. 5-25, 303-321, 323-337.

15

DEVELOPMENT OF OIL FINISH FROM CASTOR PLANT (Ricinus communis L.) SEEDS

Yolanda L. Tavita and Adelina E. Manas 1

ABSTllACT

Oil from castor beans was studied for suitability as ·a finishing material in furniture.

The beans yielded about 48.5% oil using the solvent extraction process. Extraction of oil by means of a manually-operated slurry press yielded 43.9% to 46.02% oil.

Raw castor oil was dehydrated to convert it from a non-drying to a drying oil. Of the two dehydration conditions tried, heating the oil at 240°C for 20 min in the presence of activated clay resulted in partial dehydration ef fee ts.

Some physical and chemical properties of raw and dehydrated castor oil such as specific gravity, viscosity, iodine value, s·aponification value, acid value and hydroxyl value were analyzed. Infrared spectrum of the oil was also determined.

Nine formulations of finishing oil using raw, dehydrated and boiled dehydrated castor oil were prepared. Along with a commercial finishing oil which served as control, the oil systems were applied on the surf aces of narra and tangile samples. Performance. evaluation was conduct~d on drying time, brushability, grain-raising property, consumption pattern and resistance to household liquids and hot and cold water.

Findings generally favor the use of boiled dehydrated castor oil over the other formulations and commercial oil.

INTRODUCTION

Wood finishing is a method of transforming raw wood into exquisitely natural finished or stained products by altering or improving the wood's appearance. Finishing protects wood from abrasion and effects of chemicals and other liquids.

In the furniture industry, one way of finishing wood is by applying finishing oils. Oil-finished furniture exude a classy, antique appearance and command a high price in the market

Oils for this purpose are called drying oils since they have the ability to absorb oxygen and thus, change from a liquid or wet form into a solid or dry form.

Statistics show that the Philippine furniture coating industry is very much dependent on imported materials. Volumewise, the largest importation is linseed oil, probably the most important oil ingredient in finishing oils~ paints, varnishes and other coating

1 Senior Science Research Specialist and Supervising Science Research Specialist respectively, FPRDI, College, Laguna 4031.

16

materials.

To reduce importation cost, local materials are being tapped as substitutes for linseed oil. For instance, the Forest Products Research and Development ·Institute in College, Laguna has developed a finishing oil from the indigenous lumbang [Aleurites moluccana (L.) Willd.] seeds.

Another promising local source of oil is the castor plant which abounds in the country. Utilizing castor oil will not only help consetve the country's foreign exchange reserves, but also give added income to farmers who raise castor plants.

Objectives

1. To determine some physical and chemical properties of raw and dehydrated castor seed oil obtained through mechanical pressing.

2. To develop a process of dehydrating castor oil.

3. To develop different ~astor oil formulations.

4. To evaluate the suitability. of the castor oil formulations as finishing materials under standard laboratory procedures.


The castor plant or "tangan-tangan" (Ricinus communis L.) belongs to the family Euphorbiaceae. It grows wildly all over the Philippines and thrives even in barren and mountainous terrain. It is a woody bush that matures within 90 days and grows from I to 4 m high (West and Brown 1920).

The fruits are spiny cluster~ which separate into seed pods when mature.

Each pod bears a bean-like seed which contains a colorless or sligh ti y greenish oil. The oil is viscous and has a faint characteristic odor, and bland or slightly acrid and usually nauseating after-taste (Redoloza 1982). About 770,000 MT of beans worldwide are processed yearly, yielding around 385,000 MT of oil (FAQ 1979).

The amount of oil in beans depends on the variety. Generally, castor beans contain about 50% oil which can be extracted by various processes or a combination of processes such as hydraulic press, continuous screw process and solvent extraction. The most satisfactory method is by hot pressing using a hydraulic press, followed by solvent extraction to remove the bulk of the remaining oil in the press cake.

Hot pressing by hydraulic press extracts between 75 to 85% of the oil in the beap.s, while the remaining press cake has about 12% oil. Subsequent solvent extraction yields the bulk of the remaining oil, leaving castor meal with an oil content of around 1-2% (FAQ 1979).

India, one of the leading producers of castor plan ts, has done considera.ble studies on utilizing castor oil and its products. Its soap industry uses castor oil. to the maximum. Indians also derive from the oil such procjq,cts as turkey red oil, dehydrated c·astor oil, hydrogenated castor oil, sebasic acid and others.

Local researches on the uses of castor oil include dehydration for paint and allied products, sulfonation to make turkey red oil, qzonolysis to make azelaic acid and the pre para ti on of castor oil-based hydraulic fluid and castor oil emulsions (Arida 1982).

Its unique composition makes castor oil particularly suited to various industrial

uses. Two grades of the oil are recognized by the trade: the colorless oil obtained by cold pressing the beans and is suitable for medicinal purposes, and the more or less colored oil obtained by further mechanical pressing or solvent extractions and is suitable for industrial purposes.

Castor oil is highly valued as a nondrying oil and is, therefore, one of the best lubricants around. Railways, textile and flour milling, industries apply large quantities of castor oil for lubrication. It is also an excellent plasticizer in lacquers. The raw oil has the following fatty acid composition (Eckey 19 54 ): 2.4 % sa tura teq acids, 3.1 % linoleic acid, 7.4% oleic acid, 87.0% ricinoieic acid and 0.6% dihydroxyl stearic acid.

Raw castor oil used as a film former will never dry. · This is because of ricinoleic acid, the oil's main component which does not have sufficient double bonds to take in oxygen and become solid.

For castor oil to have the essential double bonds, it must be dehydrated. During dehydration, a double bond is formed at the point in the riCinoleic acid chain where a hydroxyl group and an adjacent hydrogen atom are removed. The ricinoleic acid is changed to linoleic acid (2-3 parts of non-conjugated form to 1 part of conjugated form) which is a drying oil (Balley 1959). The reaction is shown below:

Ricinoleic acid

17

Dehydrated cas.tor oil contains . 0.5% saturated acids, 5.0% hydroxyl acids, 7.5% oleic acid, 65% 9, 12 linoleic acid, and 22% 9, 11 linoleio acid (Terrill 1950).

Dehydrated castor oil shows improved drying and polymerizing properties. It is available at viscosities ranging from that of unpolymerized products (about 1.5 poises) to very viscous polymerized oils. The most commonly used grade is the one polymerized to z2 - z3 (Gardner-Holdt viscosity) or about 40 poises.

Two distinct classes of products are produced when castor oil is deh.ydrated: non-drying mineral oil soluble products for partial dehydration, and excellent drying oil for complete dehydration.

The traditional methods of preparing dehydrated oil involve either destructively distilling the oil and esterifying the residue, or dehydrating the separated fa tty acids in the presence of a catalyst and esterifying the dehydrated fatty acids with glycerol. Such methods result in partial dehydration and consequently, poor drying oils. With improvements in operating conditions and equipment as well as catalyst types, more complete dehydrated castor oils ·possessing good drying properties have been produced.

Dehydration in commercial quantities is carried out in large stainless steel kettles equipped with an agitator. The oil is heated with steam under vacuum.

9,11 Linoleic acid (conjugated form)

+

HHHHH I I I I I

CH3(CH2)4-C•C-C-C•C-(CH2)7COOH I H

9, 12 Linoleic acid (non-conjugated form)

18

The catalyst is added either before heating or when the oil reaches the desired temperature of 250-30o0 c. It is heated with Dowtherm, direct fired or electric, to 250-300°C under vacuum to pull off the water which is formed. The catalyst generally used is of a~ acidic nature, such as potassium and sodium acid sulfate, sulfuric acid, phosphoric acid, pthalic anhydride, acid earth, tungstic oxide and others; Other recommended catalysts arc activated earth, polybasic acids and metallic chlorides (Kirls-O•hmer 1954).

Eleven samples of Philippine clays are found to be suitable catalysts for castor oil d~hydration. The clays come from Zambales, Rizal, Nueva Ecija and Cebu. Imported Fuller's -earth Is also used (Canchela and Cruz 1955).

Generally, most properties of dehydrated castor oil fall between linseed oil and tung oil. It finds wider usage in finishes that require initially good color and retention. It is used to some extent ·in alkyd resin manufacture. Aside from being an excellent varnish oil, it is also used in the paint industry.


Materials

Test panels from two commercial wood species namely: narra (Pterocarpus indicus Willd.) and tangile [Shorea polysperma (Blanco) Merr.].

. Brazilian variety castor beans purchased from a plantation in Naic, Cavite

. Clay from Liliw, Laguna

. Paint thinner

. Driers (240/o lead naphthenate and 60/o cobalt naphthenate)

. Abrasives (120, 220, 320 grit numbers)

Household ·liquids (coff ec, softdrinks, 450/o alcohol, cold and hot water)

Preparation of Wood Specimens

Plain-sawn narra and tangilc lumbers 2.5 cm thick and kiln-dried to 5-7% MC were purchased .from the Industrial Development Corporation, Quezon City. The lumber Were further processed into 1x7x17 cm experimental samples.

Samples were then smoothened using the 120-220-320 sanding schedule which was found ideal for both narra and tangile (Moredo and Ta vita 1986).

Preparation of Oil

. Extracti.on of castor oil

Solvent extraction. Following the procedure of the American Oil Chemists' Society (Cooks and Von Rede 1966), kernels were chopped into small pieces. One gram of kernel was placed in a filter paper pocket, then in a Soxhlet extractor. Two hundred milliliters of hexane were placed in a 250-ml Soxhlct flask and extraction was conducted for 8 hr.

The filter paper pocket_ was removed and placed under a hood to remove the solvent, oven-dried at 105° and weighed. The oil content was calculated from the weight of the residue.

Mechanical extraction. Castor bean kernels were chopped into fine particles .and placed in a forced-draft oven at 45°C for 38-48 hr to remove the water. The dried kernels were wrapped in nylon tulle and oil was extracted using a manually operated slurry press with a pressure of 5.52 MPa for 8 hrs.

• Analysis of raw castor oil

In accordance with the standard procedures of the American Oil Chemist's Society (I 966), the following properties of raw oil were determined: iodine number, . acid value and saponication number. The hydroxyl value was also determined in accordance with the standard procedures of the Association of Official Agricultural Chemists Society (1965).

The infrared spectra of the raw and dehydrated oils were measured with a Perkin Infra-red Spectrophotometer Model 735 B.

. Dehydration of castor oil

Method I. Six hundred grams of oil were placed in a I-Ii capacity round neck flask. The oil was heated to 240°C on a heating mantle and 42 gm of activated clay (prepared by heating the clay to 60o0 c for 3 hr) was added. The mixture was stirred and heated for 20 min. The treated oil was filtered with the aid of suction to remove the clay.'

Method 2. Another oil sample was dehydrated following the same procedure, al though the temperature used was 280°C and heating time was 7 min.

. Analysis of the dehydrated oil

The physical and chemical properties of the dehydrated oil were analyzed following the: same procedures in the· analysis of raw oil.

Formulation of Oil Finishes

Formulation of the different oil systems was patterned after that of lumbang oil in a previous study by Moredo and Tavita (1986).

19

. Raw castor oil

Raw oil extracted from finely chopped kernels using tl, manually-operated slurry press was used. Three oil finish systems (500 ml each) with the following compositions were prepared.

Components

Raw castor oil

Paint thinner

Systems % by volume

ROI ROii ROIII

50

50

33.3

66.7

25

75

. Dehydrated castor oil

Three formulations of dehydrated castor oil (500 ml each) obtained from Method I were prepared as follows:

Components

Dehydrated castor oil

Paint thinner

Systems, % by volume

DOI DOii DOIII

50 33.3

50 66.7

25 75

• Boiled dehydrated castor oil

Dehydrated castor oil was heated to boiling tempera tu re for 30 min after which 24% lead naphthenate and 6% cobalt naphthenate were added. Three formulations (500 ml each) with the following compositions were prepared:

Components

Boiled dehydrated oil

Paint thinner

24% lead naphthenate

6% cobalt napthenate

Systems, % by volume

BDOI BDOll BDOIII

50 33.3 25

50 66.7 75

1.5% by weight of oil

0.5% by weight of oil

Testing of Formulated Products

The formulated oil systems were brushed on properly sanded surfaces of narra and tangile samples. A commercial finishing oil ~as included

20

to serve as reference material in evaluating the suitability of the formulated products as furnitur·e finishes. Five samples each ·of narra and tangile were e.lloca ted for each of the nine formulations and the reference oil. Perr ormance tests conducted on lumbang oil (Moredo and Tavita 1986) were also made on castor oil:

• Drying time

This referred to the time required for the finish - to dry to touch and to recoat, and measure.d subjectively by experienced finishers.

• Grain-raising property

This referred to the, capacity of the finish to raise the grain of wood. It was determined by observing the finish under a 20x hand lens against a clear white background. The following system was adopted in evaluating the grain·-raising property of applied oils:

Rating

6 = no.grain-raising 4 =~few/localised grain-raisinc

S = moderate grain-raiainc

2 = advanced grain-raising

1 = widespread/ excessive

grain-raiainc

• Consumption pattern

Coverage:

09' of section

1-109' ofaection

11-20% of section

21-'19% of section

80-100% of section

This referred to. the number of coats required to produce an acceptable

_ finish quality.

• Resistance to liquids

This test revealed the damage caused by accidental spillage of comQlon

- household liquids such as coffee, alcohol, softdrinks and fruit juice. A 25 mm absorbent pad was soaked in the test liquids (hot coffee, 45% alcohol and cold sof tdrinks), placed on the

finished sample and then covered with a watch glass. The pad was removed after I hr and excess liquid was wiped off. After 16 hr, the test area was examined and any marks left by the liquid were assessed on a scale rating of l (finish wholly or partially removed) to 5 (no damage).

• Cold water resistance

Finished panels were immersed in distilled water maintained at room temperature. After 18 hr, the panels were removed from water and allowed to dry for 2 hr. These were then examined for dulling~ whitening or blistering._ Assessments were made on a scale rating of 5 (no dulling, whitening or blistering) to 1 (excessive dulling, whitening or blistering).

• Hot water resistance

Panels applied with finishing oil were immersed in boiling distilled water for 15 min, after which they were allowed to dry· for 2 hr. Assessment of hot water .resistance was similar ·to that' described in cold water resistance.

Statistical Analysis of Data

Properties and performance of raw, dehydrated and boiled dehydrated castor oil were statistically evaluated using the completely randomized design (CRD), the Duncan's Multiple Range Test (DMRT) whenever th~ effects of variables were founq significant, and the Kruskal-Wallis One-Way ANOVA by Ranks.

RESULTS AND DISCUSSION

Extraction of Castor Seed Oil

Extraction by a manually-operated slurry press (Table l) yielded an average of 44.67% oil. Further extraction of the residue using a

21

Table 1. Oil yield obtained by extraction with hydraulic press

INITIAL WEIGHT OF SEEPS (gm)

WEIGHT OF RESIDUE AFTER EXTRACTION WITH OiL

% OIL EXTRACTED

2000 2000 2000

AVERAGE

Table 2. Oil yield of castor beans by solvent extraction method

First trial Second trial AVERAGE

OIL YIELD (%)a

47.21 49.84 48.52

a Based on weight of m.oisture free seeds

solvent like petroleum ether yielded oil ranging from 3.85 to 4.61 %. The oil obtained was · translucent with a specific gravity of 0.9742.

For comparison purposes, oil was also extracted from the beans by solvent extraction method (Table 2) which yielded a higher percentage (48.52%).

Dehydration of Castor Oil

Preliminary deh:ydration using ordinary clay as catalyst yielded a very dark oil so that activated clay was used.

Raw castor oil was dehydrated under two conditions: heating the oil with activated clay at 280°c for 7 min, and heating the oil with activated clay at 240°c for 20 min.

881.8 887.7

1121.7

44.09 46.02 43.91 44.67

Physical and Chemical Properties of Castor Oil

Some ph¥sical and chemical properties of raw and dehydra~ed castor oil together with those of commercial finishing oil are presented in Table 3.

The ANOVA results of the chemical analysis showed very significant decreases in acid values from 14.35 to 8.11 to 7.52 (Table 4). The decrease might be due to the breakdown of the free ricinoleic acid to its esters. When ricinoleic acid is stored or heated, as in the case of dehydration, estolides. (sometimes called polyricinoleates) are formed. These result from the reaction of the hydroxyl group with the carboxyl group of ricinoleic acid splitting off water and forming an ester group.

A completely dehydrated oil, however, should have an acid number of about 6 or less than 4 for better commerdal dehydrated oils.

The iodine value is a measure of unsa tura tion of the oil. When castor oil is heated in the presence of certain catalysts, the elements of water are split from the ricinoleic acid. The · removal. of the hyd'l'oxyl COH) group and an adjacent .hydrogen atom results in the formation of a new double bond

22

Table 3. Physical and chem1cal properties of raw and dehydrated castor oil

CASTOR OIL

RAW OIL DSHYDRATED OILO COMMERCIAL 240 c 280 c FINISHING OIL

for 20 min for 7 min

Acid value 14.35 7.52 ·s.11 8.38 Iodine value 83.06 84.14 82.95 112.80 Hydroxyl value 210.29 165.40 201.85 Saponification No. 192.99 186.91 185.52 165.40 Viscosity (cps) at 25°c 462.5 520.0 526.0 Specific gravity 0.974

Table 4. ANOVA for acid values

S(XJRCE OF VARIATION DF SUM OF SQUARES MEAN SQUARE F VALUE

Between 3 59.980 19.993 232.650** Within 4 .344 .086 Total 7 60.324

Table 5. ANOVA for iodine values

SOURCE OF VARIATION DF SUM OF SQUARES MEAN SQUARE F VALUE

Between 3 1382.615 460.872 269.303 ns Within 6 10.269 1. 71 Total 5 1392.883 9

Table 6. ANOVA for hydroxyl values


* Between 2 2279.655 1139.833 17.950 Within 3 190.498 63.499 Total 3 2470.16 5

Table 7. ANOVA for saponification number


Between 3 63.230 21.077 6.223ns .Within 4 13.548 3.387 Total 7 76.778

in the fatty ~cid chain, thus changing the ricinoleic acid to linoleic acid (see reaction on page 3).

In both dehydration methods performed in the labo·ratory, however, there was no significant increase in the iodine values imparted to the oil (Table 5). This means that no increase in unsaturation was achieved from the reaction as the two isomers of linoleic acid were not yet formed or the reaction was still incomplete.

Of significance is the relationship of iodine number to viscosity. Terril (1959) found in his dehydration studies that iodine value was inversely related to viscosity. He observed that at the start of dehydration; viscosity was at its maximum and iodine value, at its minimum. Further heating of the oil increased iodine value but decreased viscosity to a minimum. After this point, any increase in viscosity was due to poclymerization.

In this study, the viscosity of raw castor oil at 25°C was 462.S centipoises. After heating the oil to 240°c, viscosity increased to 520 centipoises and 526 centipoises after heating at 2so0 c. The high viscosity exhibited by the heated oils indicates that they had almost attained the maximum. Further heating was, therefore, necessary to complete the reaction which could increase iodine value and decrease viscosity.

Heating the oil at 240°C for 20 min imparted partial dehydration as in di ca ted in the sign if ican t decrease of ·oH values from 210.2 to 165.40 (Table 6). The latter value is still high considering that a completely dehydrated oil should have an ·oH value of 0. Even under the most severe dehydrating conditions, an ·oH value of 0 has never been obtained yet (Bolley 1959).

23

A measure of the purity of the oil as indicated by its total fatty acid content - whether combined with glycerine, or uncombined. and free - was determined by saponification number. Raw castor oil gave a saponification number of 192.98. Dehydrating the oil did not significantly change the value (Table 7).

The free ·oH group could be seen in the spectra of raw castor oil and even after oils were subjected to dehydration reactions (Figs. 1 to 3). The ·oH group was visible at the absorption region of 2.8 u, and in regions 3 and 3.5. u, 6.8 u and 11 u. The absorptions were similar in the three spectra. The narrowing of" the peak at 6.8 u (Fig. 2) indicates partial dehydration due to a decrease in the ·oH group. The more pronounced peaks at 6.2 to 6.8 u indicate the start of the f orma ti on of a conjugated C = C bond (Pouchert 1982).

Testing of Formulated Products

. Drying time

Tables Sa, 8b and 8c show the ANOV A results of the drying times of nine oil formulations and the commercial finishing oil. Tables 9a, 9b and 9c present the DMRT results of the same oil formulations. When applied on narra and tangile, the differences in drying times of the oil systems were found to be highly significant. The drying patterns were also ·similar in both species, with the raw oil drying faster than dehydrated and boiled dehydrated oils. A small amount of moisture was frequently present during dehydration. Failure to control hydrolysis during dehydration might have resulted in the presence of a little moisture· which prolonged the drying time. Formulations with lower oil contents gave shorter drying times than those with more oil and the commercial oil.

24

MICROMETERS (Jllll) ,0 ~ 8 7 8 9 ID II 121514 •112021

10

I !•o I .. 40

i .. 20

Figure 1. Spectrum of raw castor oil.

MICRClllUElltS (JI•) U 1.0 :·1.1 4.0 I 8 7 . I 9 IO II 121114 18•IOl5

•'° g I ieo -! ~40 Ill

I r

ao -

01--~t----.~-W--~-t-~---~...++-T~--~ ..... ~..,.-~..-__,,q,.._., 4000 3800 l200

Figure 2 .. Spectrum· of castor oil dehydrated at 240°C for 20 min.

MICROMETERS (J1•)

2.1 1.0 I.I 4.0 I 8 7 I 9 IOlll211Ml8•10B

z80 0

i ieo I ~40

I o----~-------~---~----..u..-.-~----iw-.:........,.-~~--.-+.1ir.f 4000 l800 HOO· 2800 2400 2000 llOO 1100 1400

l'REGUEllCY ( CM:.I)

Figure 3. Spectrum of castor oil dehydrated at 280°C for 7 min.

25

Table Sa. ANOVA on the drying time of finishing oils applied on tangile

SOURCE OF VARIATION SUM OF SQUARES DF MEAN SQUARE F VALUE

Between 39.409 9 ** 4.378 218.883 Within .800 40 .020 Total 40.201 49

** Highly significant

Table Sb. ANOVA on the drying time of finishing oils applied on narra

SOURCE OF VARIATION SUM OF SQUARES DF MEAN SQUARE F VALUE

** Between 54.879 9 6.098 112.526 Within 2.168 40 .054 Total 57.046 49


Table Sc. ANOVA on the drying time of finishing oils applied on narra and tangile

SOURCE OF VARIATION SUM OF SQUARES

Between 99.648 Within 2.968 Total 102.618


Some implications can be derived from the faster drying times exhibited by t~ raw oil systems and the low oil content formulations. In practical application, it becomes significant since fast drying period will mean higher volume of production, reduced labor cost and faster turnover without sacrificing quality of finish. But this criterion alone cannot favor raw oil. Thus, other tests must be considered. On the other hand, slower drying oils like dehydrated and boiled dehydrated oil systems possess the ability to

DF MEAN SQUARE F VALUE

* 19 5.245 141.384 80 .037 99

penetrate more into the wood before drying takes place, thus attaining a well-oiled surface. Dehydrating the oil and boiling it again make use of extra processes and ingredients that increase production cost. This, however, may be compensated by the better performance properties of dehydrated oil systems such as good flexibility, tough dry and good retention of color and gloss.

Comparing the oil performance on the two wood species, oil dried faster on tangile than on narra. This may be

26

Table 9a. DMRT of the drying time of finishing oils applied on tangile

TREATMENT MEAN

1 T-CFO 1.648 g 2 T-ROI 2.080 b 3 T-ROll .370e 4 T- ROIII .180 f 5 T-DOI 1.714 e 6 _ T- DOii .884d 7 T-DOIII .420e 8 T- BDOI S.050 • 9 T- BDOII .624 de

10 T-.BDOIII .510 e

Table 9b. DMRT of the drying time of finishing oils

applied on narra

TREATMENT MEAN

1 N-CFO 1.682 c

2 N-ROI 2.218 b

s N - ROii ~470 e

4 N - ROIII .226 e

5 N-DOI 2.346 b

6 N - DOii 1.584 c

7 N-DOlll .932 d

8 N-BDOI 4.096 a

9 N .. BDOII 1.384 c

10 N - BDOIII 1.226 cd

explained in terms of anatomical properties. ·Tangile possesses a coarser texture and mostly large solitary pores or vessels necessary for oil penetration, resulting in shorter time to recoa t. Narra is denser and has a finer texture and smaller pores or vessels, resulting in slower drying period for the applied oils.

• -Grain-raising property

Except for ROIII, th~ grain-raising properties of the formulated oil ·sy.stems were not significantly different from those of commercial oil

Table 9c. DMRT of the drying time of finishing oils

applied on narra and· tangile

TREATMENT MEAN

1 N-CFO 1.682 da 2 N-ROI 2.218 c s N- ROii .470 jk 4 N - ROIII .226 k 5 N-DOI 2.346 c 6 N- DOii 1.534 ef 7 N - DOIII .932 gh 8 N- BDOI 4.096 a 9 N- BDOiI 1.384 ef

10 N - BDOIII 1.226 fg 11 T-CFO 1.648 de 12 T-ROI 2.080 cd 13 T- ROii .370 jk 14 T - ROIII .180 k 15 T-DOI 1.714 de 16 T- DOii .884 gh 17 T - DOIII .420 jk 18 T-BDOI S.050 b 19 T- BDOII .624 hi 20 T-BDOW .510 kl

(Table 10). Tangile wood applied with low oil formulation exhibited few /localized grain-raising. No grainraising was observed on narra samples. Again, the anatomical properties of both species may explain the occurrence of grain-raising on tangile and its absence on narra.

In furniture finishing, grain-raising results in an inferior finish quality. Thus, sanding 1s necessary to restore the desired surf ace smoothness before a recoat is applied. Finishes which do not significantly produce grain-raising in wood are preferred in furniture finishing .

• Consumption pattern

For the low oil formulations, i.e., ROii and ROUI, DOii AND DOIII, BDOII

and BDOIII, three coats of oil were applied to attain initial finish quality.

· For the high oil formulations, i.e., ROI, DOI and BDOI, only two coats of oil were applied, just as the case with the commercial oil.

. Resistance to liquids and hot and cold water

Liquids. Resistance of raw oils -of lower concen tra ti on to 45% alcohol -was significantly low compared with the other formulations, including the reference_ oil (Table 10). Whitenin·g and loss of luster were observed on the surf aces of tangile and narra. Of significance was the performance of boiled dehyqrated oil which performed better than commercial oil on tangile. However, this was not manifested on narra, resulting in the significant differences between the two species applied with the same BDOI.

In terms of resistance to hot coffee, raw and dehydrat~d oils were not

27

significantly different from commercial oil when applied on narra. But boiled dehydrated . oil especially BDOI was found to be significantly

'different. In tangile samples, raw oil of low concentration was less resistant to the liquid than the reference oil. Thinning out of finish and loss of luster were observed on the wood surfaces. Boiled dehydrated oil exceeded the performances of the other oil systems -including the commercial oil.

Softdrinks had the least effect on the formulated oil systems. Minimal loss of luster was observed on both wood samples. Dehydrated and boiled dehydrated oil systems performed better than the reference oil. Results for raw oil, however, were not significantly different from those of the reference oil.

Cold water. The boiled dehydrated oil systems (BDOI and BDOII) performed better than commercial oil when

Table 10. ANOVA on the different properties of finishing oils

* TREATMENTS GRAIN-RAISING R E S I S T A N C E T 0 PROPERTY

45% ALCOHOL COFFEE- SOFTDRINKS COLD WATER HOT WATER

N · CFO a be b c d c N - ROI a be b c cd ab N - ROii a d b c d d N - ROii I a d b c cd cd N · DOI a be b a bed be N - DOii a be b a cd c N - DOii I a bed b a cd cd N · BDOI a abe a a a a N • 80011 a abe b a b a N - BDOII I a abe b be d cd T - CFO ab ab b c cd c T · ROI ab abc b be bed abe T ~ ROii ab d b c cd cd T - ROI II be cd b c d cd T · DOI ab abe b ab be abc T - DOU ab be b ab bed abc T - DOii I ab be b be cd be T · BDOI .ab a a a ab a T - BDOl 1 abc abe b a bed a T - BDOIU abc abe b be cd c

* Treatments with same letter are not significantly different from each other

28

applied on narra (Table IO). Both were significantly different from the raw and dehydrated oils. When applied on tangile, the dehydrated oils DOI and DOii and boiled dehydrated oil BbOI yielded better resistance values than commercial oil. After immersion in water, the tangile samples turned blackish and the narra samples yellowish. Extractives present in both wood species might have affected the performance of the finishing oils.

Hot water. The resistance of oil fqrmulations to hot water followed a trend similar to that obtained from the cold water test (Table 10). Boiled dehydrated oil systems (BDOI and BDOII) applied on tangile and narra showed better resistance values than commercial oil, raw oil and dehydrated oil systems. ·

The occurrence of dulling and whitening of the finished surface resulting from contact between oil and . wat~r has been reported by Hess (1952). The film of oil can take up water by sorption which leads to "intermolecular swelling of the film. Subjecting the oil to 45% alcohol, hot ~off ee and cold softdrinks likewise resulted in the whitening of the film due to appreciable amounts of water contained in these liquids.

Cost Analysis

A cost analysis for BDOI formulation, which showed the most prom1smg results in the laboratory, was made. Based on a 4-li volume, production cost for this formulation as of 1989 will be P85.00, compared to commercial finishing oil whkh costs P 160.00.

Itemized cost for a gallon of castor finishing oil (I part oil:l part paint thinner) is as follows:

· Cost of seeds Labor (ex traction

and dehydration) Electricity Paint thinnet Driers

Total

where: 1 kg seed = P5.00

=

=

P26.65 15.00

8.40 27.50 7.45

P85.00

1 kg seed = 83% kernels = 830 g kernel

830 x 44% = 375 ml/oil/kg seed

CONCLUSIONS AND RECOMMEND A TIO NS

There are bright prospects for formulating furniture finishes from castor oil, with properties equal to or even better than those of commercial formulations.

Application of the formulated finishes has been confined only in the laboratory. Thus, service testing should be done to determine the acceptability of the finishes to manufacturers and consumers.

The production of BDOI and BDOII system is ready for piloting. However, improvements are needed in the dehydration process. The dehydration method tried in the study resulted in partially dehydrated oil. Further studies should be done to produce a more dehydrated castor oil suitable even in paint formulations.

29

REFERENCES

AOAC. 1965. Official methods of analysis. Association of Official Agricultural Chemists Washington, D.C.

ARIDA, V. 1982. Products of industrial oils and by products: its processing and utilization. NSTA Techno. J. 3(1):88-96.

BOLLEY, D. 1959. Dehydrated castor oil. J. Am. Oil Chem Soc. 36:519-523.

CANCHELA G. and A. CRUZ. 1955. Dehydration of castor oil for paints and allied products using local dehydrating materials. Phil. J: Sci. 1:302.

COCKS, L. and C. VON REDE. 1966. Laboratory handbook for oil and fat analysis. Academic Press, London. New York. 150-157

ECKY, E. 1954. Vegetable fats and oils. 35 Reinhold Publishing Corp., New York. 184, 595-596

FAQ. 1979. FAQ Production Yearbook.

HESS, M 1952. Paint film defects: their causes and cure. Reinhold Publishing Corpora ti on, New York.

KIRK, R. and D. OTHMER. 1953. Encyclopedia of Chemical Technology 3:327-244 . .Interscience Encyclopedia Inc., New York.

MOREDO, F.C. and Y.L. TAVITA. 1986. Development/Improvement of finishing materials and techniques suitable for furniture. FPRDI .Library, College, Laguna.

POUCHERT, C. 1982. The Aldrich library of infrared spectra. Aldrich Chem. Co., New York. 268-281.

REDOLOZA, L. 1982. Castor oil: a highly promising energy alternative. Canopy International 8:11.

TERRILL, R.L. 1950. Dehydration of castor oil. J. Am. Oil Chem. Soc. 27:477.

WEST, A. and W. BROWN. 1920. Philippine resins, gums, seed oils and essential oils. In Brown. Minor Produc.ts of Philippine Forest. Dept. of Agric. and Natural Resources. Bureau of Forestry. Bulletin No. 22. Vol. II.

30

PROPERTIES OF SOME PHILIPPINE ERECT PALMS

Zenita B. Espiloy, Mario M. Maruzzo, Mariluz SP. Dionglay and Marina A. Alipon1

ABSTRACT

The study sought to determine -the different properties of erect palms and to evaluate the interrelationships of the chemical, physical and mechnical properties to their anatomical characteristics and properties within and among di/ ferent species.

Five mature trunks each of six palm_ species were studied. These were anahau ( Livistona. rotundi folia (Lam.) Mart. var. luzonensis Becc.), bunga ( ~ c_atechu L.),

. bur.i (Corvpha elata Roxb.), kaong [ Arenga pinnata (Wurmb) Merr.], J!Ugahan (Carvota cumingii Lodd.) and tarau ( Livistona siribas (Lam.) Merr.). Tests for anatomical, chemical and physical properties represented three height levels (butt, middle and top), while mechanical propertie~ tests represented only the butt and midr;lle at green condition.

Results showed that the stems of the di/ ferent erect palm species contained hard fibrovascular bundles scattered in a softer parenchymatous ground tissue. There was a high level of significance between species and height levels in moisture content, relative density and shrinkage characteristics.

Maximum crushing strength, shear, hardness and static bending were found higher in values at the butt than at the middle of the trunk. Almost all chemical components showed a high degree of significance between species and height levels, except for silica and alcohol-benzene solubility which were insignificant between· species.

INTRODUCTION

Palms belong to the botanical family Palmae and rank third in importance to grasses and legumes. The tropical zone is.: the homeland of most of the world's 2700 palm species, and of these, more than 50 yield useful products (Sastry 198 7). The Philippines is endowed with 123 species (Brown and Merrill 1920). There are very few palm species in settled areas, but these are frequently conspicious either because of their abundance as in coconuts grown in plantation, o·r their great size in the case of buri.

Morphologically, palms are a U1" ique and isolated group of monocotyledons .. These are further classified into subdivisions suggested by anatomical evidence which possess distinctive anatomical features and structural peculiarities by which they can be recognized (Tomlinson 1961). Bunga is an Arecoid palm; kaong and pugahan are Caryotoids; anahau, buri and tarau are Sa baloid palms.

From the economic standpoint, palms . provide edible fruits, oilseeds, sap for

1 Supervising Science Research Specialist and Science Research Specialists II respectively, FPRDI, College, Laguna 4031.

beverages, sweeteners, traditional medicine, palm hearts/buds, stem starch, leaves for thatching . and basketry, leaf midribs for furniture, brooms and fencing, wax for candles, fuel wood, feed for livestock, trunk wood for construction~ furniture, tool handles and other turn'ed products. When planted in large scale, . palms enhance the beauty of the landscape due to their cool green color. Because of their aesthetic value, there is a growing demand for the cultivation of palms either as a hobby or as a way of augmenting income.

Low-cost housing is a high-priority program of all countries in the world. Population growth, urbanization and the increasing growth of slums and squatter colonies all contribute to the urgency of the housing problem. Building materials obviously play an important part in any consideration of housing for low to middle-income people in developing areas.

Because of the high prices of traditionally used timber species and the need for building materials that are locally available, replenishable and reusable, the use of other potential non-timber forest products like palms will surely augment the materials for housing. Moreover, the possible utilization of the hard portion of palm trunks will help also the furniture industry considering that its main problem is the growing scarcity of traditional wood species (Mosteiro 1987).

To fishpen operators, anahau poles are more durable and stronger than bamboo because they can withstand at par tough waves and typhoons, if properly installed (Maligalig •and Abrenilla 1985).

The world's demand for palm products especially palm oil, furniture and other handicraft items is increasing while

31

supply is diminishing. If buri, anahau, kaong, pugahan, bunga, tara u and other palm species can be propagated, harnessed and their potentials fully tapped, then stl'bstantial increase in income can be attained which augurs well for the country's economy (Uddin 1985).

Objectives

1. To determine the different properties of erect palms, namely: relative density, moisture content, shrinkage, fibrovascular bundle, frequency fiber and vessel measurements, compressive and bending properties, shear, toughness, hardness and pro xi mate chemical analysis including starch and silica contents.

2. To evaluate the interrelationships of the chemical, physical and mechanical properties with the anatomical characteristics and pr9perties within and among different species.


Five mature trunks each of six . palm species, namely: anahau [livistonn rotundifolia (Lam.) Mart. var. luzonehsis Becc.], bunga (Areca catechu L.), buri (Corypha e/ata Roxb.), kaong [Arenga pinnata (Wurmb) Merr.]; puga:han (Carvota cumingii Lodd.) and tarau [Livistona saribas (Lour.) Merr.] were collected in Catanauan, Quezon; Makiling forest, College,· Laguna; Quirino, Isabela, and Sta. Ana, Cagayan.

The sampling scheme for this study is shown in Figure 1. Tests for anatomical, chemical and physical properties represented three height levels (l?utt, middle and top), while tests for mechanical properties

32

4

1-T 5

2

1-M

4

2

1-8

4 1-------

2

-~ .. J _____ --4

4

s

2

Section 4. Determination of.· mechanical properties i.e. comprealve and bencllno strenoths , shear, hardness, touohness

Section 3 - RelatlvT density and mo sture content C a ) determination

·section 2 - Shrlnkaoe ( b) chemical composition, starch and sll lca contents ( c) determinations

Section I - Fibro-·vaM"ular bundle frequency and cllm• 1lon1 ef fiber and VUHI (d) determination

Figure .1. Sampling scheme used for obtaining specimens from a palm tree.

represented only the butt and middle at green condition.

A~atomical Propertie~

Fibrovascular bundle f reguency getermination. Discs 5 cm thick were smoothened to get perfectly clean crosssections. The number of fibrovascular bundles per unit area was determined directly from the cross-sectional discs using a calibrated magnifier magnified 20x. Fifty determinations per sample representing three radial portions (dermal, sub-dermal and central regions) were made.

Fiber and vessel mensuration. Matchstick-size splints obtained from the three radial portions were prepared and, macerated in an equal volume of 60% . glacial acet.fo acid and 30% hydrogen peroxide. Maceration was done in water bath. The samples were then heated for about 1-2 hr or until whitish and soft, washed in running water until acid~free, and finally soaked in 50% ethyl alcohol. . Prior to fiber and vessel mensuration, the test tubes were shaken to separate the different structural elements. Fifty determinations per: sample were made using a binocular microscope. The length, width, lumen 'diameter and cell wall thickness of fibers as well as length and diaineter of vessel elements were determined and evaluated.

Macroscopic/Microscopic observation. Blocks measuring 1 x I x2 cm , and representing the three radial · zones were obtained from the smoothened discs (Fig .. 2). These were boiled and their cross-sections smoothened by a sharp razor blade. Photomacrographs of !Ox ·magnification were taken from these blocks.

The blocks were boiled further uJtiI ready for sectioning with a slid.ing microtome. Slides were prepared, observed and studied and

33

Figure 2. The di/ ferent radial zones in a typical palm~

photomicrograph illustrations of important anatomical features were made (Figs. 3 and 4).

Chemical Properties

Sample discs, , I 0 cm thick, were obtained starting at 30 cm above ground level. The discs were debarked manually, cleaned, chipped and airdried. Composite sampling of the five discs was done for the butt~ middle and top. The samples were then ground-in a Wiley mill, sieved to pass through the 40 mesl}, screen wire and retained on a 60 mesh screen wire. The samples retained at 60 mesh were used in the chemical analysis. Some samples were allowed to pass through the 200 mesh sieve for use in the starch content analysis.

The procedures used for analyzing the chemical components (alcohol-benzene extractives~ hot water extractives, lignin, pentosans, I o/o NaOH solution, starch, silica, holocellulose and ash) are standard methods of the Technical Association of the Pulp and Paper Industry {T APPi) except for lignin (modified method by Effland) and silica (sulfuric acid method by Nicolas).

_J

34

Figure 3. Transverse sections (80x) of pair(' species A. Livistona rotundi folia B. Areca catechu C Corypha elata D. Arenga pinnata E. Livistona saribas

:Figure 4.

A,B: Longitudinal sections of Corvpha elata with vessel elements surrounded by helical (W) wall thickenings and with scalarijorm per /oration (SP) plates in profile (80x) and silica (Si) bodies arranged in longitudinal rows between the fiber sheath (FS) and adjoining parenchyma (P) cells (150x).

C: Starch globules ( S) in Corvpha el at a ground sample ( 200x ).

D: Longitudinal section of Areca catechu showing raphides ( R) contained in raphide sacs ( 150x)

35

36

Physico-Mechanical Properties

The testing methods for the physical and mechanical properties (moisture content and relative density, shrinkage characteristics, static bending, compression parallel to grain, shear parallel to grain, hardness and toughness) were adopted from the American Society for Testing and Materials Designation: Dl43-52 (Revised 1972): Standard Methods of Testing Small Clear Specimens of Timber.

Statistical Analysis

Data on the different properties were analyzed statistically using the Complete Randomized Design (CRD) with subsampling. However, the physical and mechanical properties of pugahan were not determined. The specimens obtained from the very limited hard dermal portion of the trunks were too soft to undergo physical and mechanical tests. Therefore, statistical analysis was only done on species with complete data, i.e., anahau, bunga, buri and tarau, for anatomical and physical properties. All species were studied for pro xi mate chemical composition analysis.


Table 1 ·shows the collection data on some Philippine erect palm species, i.e., average merc.hantable height and diameter of trunk at three height levels. Buri is the tallest ( 13.54 m) and biggest in average trunk diameter (54.60 cm). Pugahan is the shortest (6.4 m), while bunga has the smallest average trunk diameter ( 13.58 cm).

The ana to mi cal properties of some Philippine erect palms which include frequency of fibrovascular bundles and data on fiber and vessel measurements are shown in Table 2. The fibrovascular bundle frequency for all species increased axially from the butt

toward the top portions and radially from the central to dermal regi~ns.

The summary of ANOV A on ana to mi cal properties showing their mean squares and statistical significance is in Table 3. All anatomical properties between spe~ies were found significant except for y~ssel diameter; insignificant between trunks except for cell wall thickness; likewise, insignificant tie tween height levels except for cell wall thickness and_ vessel length.

The high level of significance for most anatomical properties between species and for some properties between trunks and height levels can be explained by the fact that the ages of the different species were not known although they might ha;ve been classified according to diameter /height class at the time of collection. The species studied were collected from different places, at different elevations and soil conditions. Moreover, differences between species might be genetic in nature. All the aforementioned factors could have affected the size, distribution, shape and arrangement of structural elements. Among the species, buri was observe4 flowering at the time of collection. According to Brown and Merrill (1921), buri grows 25 to 30 more years, during which large quantities of starch collect in the trunk, then it flowers once and eventually dies.

In Uchimura's study on bamboo (1978), several theories were cited regarding the causes of flowering. It could be pathological, periodical, mutational, nutritional or due to man-made practices such as fire and clear cutting. All these theories are only based on observations and whichever theory is applicable to whatever palm species. is subject to further studies and verif ica ti on. Table 4 shows the physical properties of the palms species studied. Table 5

shows the summary of ANOV A on physical properties of four palm species (anahau, bunga, buri and tarau). Moisture content and shrinkage characteristics between species and height levels were found highly significant but insignificant between trunks. Relative density, on the other hand, showed a high degree of significance between species, trunks· and height levels. It is interesting to note that cell wall thickness exhibited the same trend as relative density (Table 3). Anatomically, relative density may be regarded as a function of the ratio of cell wall volume to cell void volume. As such, it is affected by cell wall thickness and structure, cell

37

wi~th, relative proportion of different types of cells, and the kind and amount o~ extractives present (Elliott 1 ~66). The data on the mechanical pfoperties (Table 6) ·1iwere not analyzed statistically due to limited samples. Some samples of bunga, kaong and tarau were found to be too soft to undergo mechanical tests. Results of the pro xi mate chemical composition of the different palm species are shown in Table 7 and the summary of ANOVA of the respective chemical components is in Table 8. Almost all chemical components showed a high degree of significance in all sources of variation except for silica· and alcohol-benzene solubility which

Table 1. Collection data on some Philippine erect palm species

SPECIES/LOCATION NO. OF TRUNKS MERCHANTABLE HEIGHT DIAMETER OF TRUNK (cm) COLLECTED OF TRUNK (m) Butt Middle Top Ave.

1. Anahau 5 12.61 19.20 18.40 16.20 17.93 [Livistona rotundifolia (Lam.) Mart. var. luzonensis Becc.l Catanauan, QJezon

2. Bung a 5 11.28 15.60 13.20 11.94 13.58 CAreca ~ L. Catanauan, Quezon

3. Buri 5 13.54 56.80 54.20 52.80 54.60 C~ elata Roxb.)' Catanauan, Quezon

4. Kaong 5 7.25 29.75 26.00 24.75 26.83 [Arenga pinnata (Wurmb.) Merr.]

5. Pug ah an 5 6.40 24.50 20.50 19.00 21.33 (Caryota cumingii Lodd.) Quirino, Isabela

6. Tarau 5 11.21 26.80 19.20 16.20 20.73 CLivistona saribas (Lour.) Merr.J Sta. Ana, Cagayan

(J.) 00

Table 2. Average anatomical properties of some Philippine erect palms

SPECIES HEIGHT RADIAL FIBROVASCULAR FIBER CHARACTERISTICS VESSEL CHARACTERISTICS LEVEL PORTION BUNDLE FREQUENCY Fiber Fiber Lunen Cell wall Vessel Vessel

(No./sq. nm) Diameter Diameter Width Thickness length Diameter (nm) (nm) (nm) (nm) (nm) Cnm)

1. Anahau Dermal 1.53 2.196 0.016 0.021 0.013 1.817 0.179 Butt Subdermal 0.75 2.072 0.037 0.017 0.010 2.312 0.258

Central 0.48 2.007 0.031 0.014 0.009 2.804 0.257

Dermal 1.66 2.056 0.043 0.021 0.011 2.183 0.200 Middle Subdermal 0.84 2.254 0.034 0.016 0.009 2.669 0.241

Central 0.43 1.994 0.028 0.013 0.008 3.501 0.283

Dermal 2.00 1.906 0.037 0.021 0.008 1.923 0.185 Top Subdermal 1.02 2.067 0.030 0.017 0.006 3.120 0.275

Central 0.47 2.034 0.029 0.016 0.006 3.460 0.269

2. Bung a Dermal 0.72 2.205 0.034 0.012 0.011 2.525 0.189 Butt Subdermal 0.46 1.659 0.033 0.011 0.011 2.832 0.202

Central 0.29 1.395 0.029 0.013 0.008 2.837 0.195


Central 0.61 1.544 0.027 0.013 0.007 3.527 0.219

Dermal 1.33 2.009 0.041 0.020 0.010 2.707 0.285 Top Subdermal 0.99 1.609 0.033 0.019 0.007 3.198 0.297

Central 0.64 1.335 0.027 0.015 0.006 3.035 0.240

3. Buri Dermal 1.56 1.251 0.035 0.018 0.008 0.707 0.207 Butt Subdermal 0.65 1.652 0.030 0.013 0.008 0.964 0.255

Central 0.37 1.m 0.028 0.011 0.008 1.285 0.283


Central 0.40 2.164 0.029 0.014 0.008 1. 700 0.299

Dermal 1. 77 1.374 0.029 0.013 0.008 0.937 0.200 Top Subdermal 0.76 1.932 0.028 0.016 0.006 1.563 0.282

Central 0.39 2.275 0.028 0.015 0.006 1.953 0.314

Table 2 ••• cont'd

SPECIES HEIGHT RADIAL FIBROVASCULAR FIBER CHARACTERISTICS VESSEL CHARACTERISTICS LEVEL PORTION BUNDLE fREQUENCY Fiber Fiber Lunen eel l wall Vessel Vessel

(No./sq. nm) Diameter Diameter Width Thickness length Diameter (nm) (nm) (nm) (nm) (nm) (nm)

4. Kaong Dermal 1.40 1. 720 0.033 0.012 0.011 0.933 0.157 Butt Subdermal 0.88 1.763 0.039 0.020 0.010 1. 751 0.201

Central 0.43 2.057 0.031 0.016 0.010 2.357 0.201


Central 0.48 1.593 0.031 0.020 0.006 2.069 0.183

Dermal 1.45 1. 754 0.036 0.011 0.013 1.258 0.148 Top Subdermal 1.11 1.667 0.-032 0.020 0.007 1.549 0.187

Central 0.52 1.336 0.027 0.018 0.005 1.734 0.170

5. Pugahan Dermal 0.90 2.211 0.033 0.013 0.010 2.380 0.240 Butt Subdermal 0.42 1.919 0.029 0.013 .0.008 2u475 0.223

Central 0.28 1.488 0.027 0.012 0.007 2.535 0.243


Central 0.46 2.117 0.030 0.015 0.008 2.258 0.246

Dermal 1.19 2.057 0.034 0.016 0.009 2.076 0.211 Top Subdermal o.n 1.n2 0.033 0.016 0.009 2.765 0.231

Central 0.50 1.476 0.027 0.015 0.006 2.545 0.200

6. Tarau Dermal 1.15 1.809 0.048 0.031 0.0.09 1.766 0.191 Butt Subdermal 0.65 1. 750 0.042 0.029 0.006 2.475 0.249

Central 0.37 1.641 0.038 0.027 0.005 2.693 0.253


Central 0.56 1.663 0.032 0.022 0.005 2.869 0.280

Dermal 1.73 1.780 0.046 0.031 0:008 1.827 0.242 Top Subdermal 0.98 1.608 0.039 0.027 0.006 2.021 0.291

Central 0.64 1.361 0.034 0.022 0.006 2.204 0.317

(Jo)

'°

40

Table 3. Surnnary of ANOVA on anatomical properties of some Philippine erect palms

SOURCE OF VARIATION MEAN SQUARES AND STATISTICAL SIGNIFICANCE

Between species (anah9u, bunga, buri, tarau)

Between trunks within species (1, 2, 3, 4,

Between height ·levels (butt, middle, top)

ns · Not significant **

5)

FIBROVASCULAR FIBER BUNDLE LENGTH FREQUENCY

** ** 0.49 1.27

7.22E·02ns 0.13ns

0.11ns 0.13ns

* · Significant at 99% level of probability · Significant at 95% level of probability

FIBER DIAMETER

** 8.76E·04

6.74E·05ns

3.80E·05ns

LUMEN CELL "ALL VESSEL VESSEL DIAMETER THICKNESS LENGTH DIAMETER

* * ** 1.31E·03 .5.91E·05 25.00 6.19E·03n:

* 2.89E·04ns 1.66E·05 0.96ns 2.11E·03n~

** ** 2.23E·04ns 1~m-06 0.82 2.84E·03m

Table 4. Average physical propetties of some Philippine erect palms

PROPERTY HEIGHT s p E c I E s SPECIES LEVEL Anahau Bung a Buri Kaong Tarau AVERAGE

1. Moisture Content (%) Butt 70.15 73.38 110.52 324.37 679.61 251.61 Middle 107.63 98.80 99.19 449.68 536.40 258.34 Top 145.38 156.65 109.25 329.52 397.72 227.70

2. Relative Density11 Butt 8.791 0.730 0.577 0.295 0.205 .520 Middle 0.627 0.618 0.596 0.232 0.210 .457 Top 0.535 0.460 0.543 0.299 0.221 .412

3. Shrf nkage (%)

a. Radial Butt 7.34 6.08 2.69 10.08 7.16 6.67 Middle 7.43 11.05 4.44 12.42 7.92 8.65 Top 11.27 12.86 5.40 22.00 10.54 12.41

b. Tangential But 6.92 5.50 3.71 9.42 9.88 7.09 Middle 7.82 8.15 5.46 7.20 11.30 8.00 Top 9.74 9.44 5.57 15.13 12.43 10.44

11 Based on volune at test and weight when ovendry.

-

41

Table 5. Sllll'llttry of ANOVA on physical properties of some Phil;ppine erect palms

SOURCE OF VARIATION MEAN SQUARES AND STATISTICAL SIGNIFICANCE MOISTURE CONTENT

Between species Canahau, buri, bunga, tarau)

Between trunks within species (1, 2, 3, 4, 5)

Between height levels (butt. middle, top)

ns • Not significant **

2.67E+06

42484.70 ns

** 36687.70

· Significant at 99% level of probability * · Significant at 95% level of probability

were found to be insignificant between species.

CONCLUSIONS

. The stems of the different erect palm species contain hard f i brovascular bundles sea ttered in a softer parenchymatous ground tissue. The bundles are more concentrated in the peripheral portion than in the central region of the transverse section of the trunk. They differ only in size, shape, distribution and arrangement of structural elements with respect to height and diameter of the trunks.

There is a high level of

**

significance between species anq height levels with regard to moisture · content, relative density and shrinka·ge characteristics. The aforementioned physical properties are found to be insignifican ti y different between trunks except for relative density which has a high

RELATIVE DENSITY

2.41

** 0.20

** 4.89E·02

SHRINKAGE Tangential Radial

** ** 373.52 395.74

68.12 "NS 36.53 ns

** ** 45.63 22.19

level of significance in all sources of variations.

Based on the averages of the species, . the strength properties, namely:

maximum crushing strength, shear, hardne~s and static bending, are higher in values at the butt than at the middle of the trunk, except for toughness which is the reverse.

Almost all chemical components show a high degree of significance between species and height levels except for silica and alcohol-benzene solubility which are insignificant between species.

RECOMMENDATION

Although palm. trunks contain hard fibrovascular bundles scattered in a parenchymatous ground tissue, there is usually a very limited hard peripheral rind surrounding the soft central region. This hard portion has

42

Table 6. Average 1nechanical properties of some Philippine erect palms

PROPERTY HEIGHT LEVEL Anahau

1. Static Bending a. Modulus of Rupture CMPa) Butt 63.1

Middle 46.8 b. Fiber stress at elastic Butt 46.8

limit CMPa) Middle 31.2 c. Modulus of elasticity Butt 8.9

CMPa) Middle 6.6 2. C~ression Parallel to Grain

Maxi11K.111 Crushing Strength Butt 31.9 CMPa) Middle

3. Toughness (Joule) a. Radial Butt 37.9

Middle 33.8 b. Tangential Butt 33.6

Middle 45.1 4. Shear CMPa)

a. Radial Butt 1.8 Middle 1.2

b. Tangential Butt 1.7 Middle 1.4

5. Hardness CkN) a. Radial Butt 1.4

Middle 0.5 b. Tangential ·Butt 2.2

Middle 1.7 c. End Butt 0.7

Middte 0.4

conside~able value and can be split into planks about 35 mm thick or less. for use as built-up members or structural components which are comprised of relatively small pieces of materials joined together by gluing or by means of mechanical fasteners. This indicates that utilization of palmwood can be maximized by lamination.

The fow natural durability of

s p E c I E s SPECIES Bung a Buri Kaong rarau AVERAGE

68.4 23.6 45.16 34.5 46.95 25.? 26.8 47.15 21 .6 33.61 44.8 18.4 30.16 21.6 32.35 15.5 18.1 35.n 13.3 22.n 10.0 3.5 4.95 4.9 6.45 3.0 3.1 4.97 2.8 4.09

38.8 20.1 18.75 20.5 26.01 25.7 24.15 13.9 21.25

32.4 15.8 28.70 4S.3 26.7 35.27 28.3 19.5 27.13 31.6 19.8 34.17

4. ~ 2.95 4.5 2.85 7.0 4.35 4.8 3.10

6.8 4.10 3.5 2.00 7.3 4.75 6.5 4.10 5.2 2.95 3.8 2.10

palmwood which makes it prone to deterioration can be overcome by proper application of economical, suitable and environmentally safe preservatives.

Furthermore, palms grown in plantation should be established in the country to alleviate the problems of decreasing wood supply.

Table 7. Average proximate chemical c01TpOsition of some Philippine erect palms

SPECIES HEIGHT CHEMICAL COMPONENTS LEVEL ASH ALC·BENZENE HOT-WATER LIGNIN PENTOSAN 1% CAUSTIC SODA SILICA HOLOCELLULOSE STARCH

% SOL. % SOL. % (%) (%) SOL. (%) (%) (%) (%)

1. Anahau Butt 1.56 3.82 1.28 30.89 19.26 19.25 0.15 62.45 0.012 Middle 1.76 5.1li· 1.80 25.11 17.95 21.68 0.18 66.19 0.034 Top 2.12 3.68 5.38 26.89 16.92 26.08 0.48 62.01 0.049

2. Bung a Butt 1.49 3.41 1.34 26.83' 12.79 19.11 1. 18 66.93 0.000046 Middle 1.88 4.10 2.50 21.36 11.98 23.22 0.32 70.16 0.054 Top 3.71 5.69 4.10 21.29 10.61 28.57 0.51 65.21 0.086

3. Buri Butt 3.91 5.93 2.79 22.06 12.60 26.03 0.1.5 65.31 0.003 Middle 2.71 5. 15 3.22 24.25 12.28 28.53 0.66 64.67 0.078 Top 4.35 3.98 9.70 22.01 14.05 29.38 1.34 59.96 0.086

4. Kaong Butt 4.91 5.56 7.64 20.67 23.05 33.94 0.59 61.22 2.474 Middle 4.65 6.27 7.44 17.91 22.70 33.52 0.26 63.73 6.360 Top 6.62 7.37 15.53 20.02 20.69 42.79 0.94 50.46 98.205

5. Pugehan Butt 3.76 6.82 13.03 19.86 19.51 40.27 0.04 56.53 75. 736 Middle 4.12 5.94 14.57 20.27 19.17 43.85 0.04 55.10 65.703 Top 4.82 4.33 12.57 21.45 19.73 39.49 0.13 57.63 67.709

6. Tarau Butt 6.81 7.64 1.98 31.41 20.14 21.46 0.30 52.16 0.003 Middle 3.13 6.17 2.81 29.03 19.02 24. 71 0~42 58.86 0.004 Top 3.75 5.02 7.02 28.74 21.94 30.08 0.48 55.47 0.003

~ (J.)

Table 8. SU1111ary of ANOVA on proximate chemical CORtJOSition of some Philippine erect palms

S<XJRCE OF VARIATION

Between Species (anahau, bunga, buri, kaong, pugahan, tarau)

Between height levels (Butt, middle, top)

ns · Not significant

ASH

* 10.95

** 2.42

ALCOHOL· BENZENE SOLUTION

5.33 ns

'** 2.40

** · Significant at 99% level of probability * · Significant at 95% level of probability.

MEAN SQUARES AND STATISTICAL SIGNIFICANCE CHEMICAL COMPONENT

HOT-WATER LIGNIN PENTOSANS 1% CAUSTIC SILICA HOLOCELLULOSE STARCH SOLUTION

** ** 117.14 95.78 104.42**

** ** ** 17.20 8.38 2.45

SODA SOLUTION

** 351.98

** 29.18

0.34 ns

** 0.19

* 132.65 5091.03

** 27.46 986.11

:t

**

**

45

REFERENCES

BROWN, W.H. and E.D. MERRILL. 1920. Philippine palms and palm products. In Minor Products of Philippine Forests. Vol. 1, Bull. No. 22. Bureau of Printing, Manila. 127-248.

ELIOTT, G.K. 1966. Wood density in conifer. Tech. Comm. No. 8 Commonwealth Forest Botany, Oxford, England.

GOODMAN, L.J. 1979. Low-9ost housing: guidelines and issues. In Goodman, Pama, Ta bujara, Razani -and- Burian (eds.). Low-cost housing technology: an east-west perspective.

MALIGALIG, B.B. and C.G. ABRENILLA. 1985. The wonder an.d potentials· of anahau. Canopy International (October-December 1985 issue). 12-13

MOSTEIRO, A.P. 1987.. Furniture· from anaha·~ [Livistona rotundifolia (Lam.) Mart.] and buri (Corypha elata Roxb.) palmwood. FPRDI J. 16(1): 46-57.

REYES, V.D. 1976. A survey of bamboo joints and structure for domestic residential houses in Luzon. FPRDI Library, College, Laguna.

SASTRY, C.B. 1987. IDRC project proposal on utilization of coconut stems and other palms (Palmwood Utilization in Asia).

TOMLINSON, P.B. 1961. Anatomy of moncotyledons II. Palmae. Oxford Clarendon Press, Amen House, London, E.C.4.

UCHIMURA, E. 1978. Ecological studies on cultivation of tropical bamboo forest in the Philippines. Bull. No. 301, Forestry and Forest Products Research Institute, Ibaraki~ Japan.

UDDIN, A.S. 1985. Palms augur well for the Philippine economy. Canopy International (October-December 1985 Issue). 4, 5, 11.

46

MACHINING AND JOINTING PROPERTIES OF WOODWOOL CEMENT BOARDS

Grecelda A. Eusebio~ Antqnio A. Salita Jr. and Julian 0. Roxas1

ABSTRACT

Five standard machining tests and a performance evaluation of butt, miter and rabbet joints were conducted on 10-, 20-, 30- and 50-mm thick woodwool cement boards produced by FPRDI. Results showed that boards could be sawn, bored, mortised and routed satisfactorily using conventional tools, provided the cutting edges were kept sharp. Planing, however, was found unsuitable. In the five machining tests, non-carbide knives and bits were observed to dull rapidly and required frequent sharpening. The use of carbi:Je cutting blade was recommended for processing.

ANOV A using completely randomized design revealed that thickness of boards and types of fasteners significantly affected the jointing properties of woodwool cement boards. The latter's joint strength was inferior to that of tangile.

Bending properties, thickness swelling, linear expansion and water absorption were improved in plastered .and tiled boards. For paintability, the average performance value was 80.12%, which is fair to good.

INTRODUCTION

Woodwool cement board (WWCB) is a mixture of shredded or chipped timber and cement, shaped or formed by pressure into the required thicknesses and sizes. The panel product is relatively light in weight, heatinsulating, sound- absorbent and fireresistant. It can be sawn and nailed as required. These qualities make it ideal for use in schools, public buildings and low-cost housing where relative cheapness, insulatiOn, sound proofing and fire resistance are matters of public concern (Flynn and Hawkes 1980).

The nanel is also suitable as kitchen

and laboratory furniture. It can withstand load or pressure when exposed to low and high temperatures and humidity to which kitchen and laboratory furniture are usually subjected to. As such, the use of WWCBs for such types of furniture merited this study.

The impact of WWCBs rests on the a vaila bili ty of local raw ~a terials and the technology for their manufacture. If found suitable, a scheme could be designed to produce pre-finished modular laboratory and kitchen cabinet for local commercialization.

1 Science Research Specialist II, Senior Science Research Specialist and Science Research Specialist II respectively, FPRDI, College, Laguna 4031.


Fraser (1977) reported that the wood cement board's amazing workability has already created keen demand for the product over a wide area. It can be sawn, nailed, screwed, glued-sanded and surfaced in the same way as the conventional resin-bonded particleboard. Swelling is negligible after weeks of continuous soaking even with unsealed edges. It is also weatherproof and fire-resistant which are major factors for its acceptability.

The cement-bonded board can be used as internal an.d external cladding in building es ta blishmen ts. Other applications are as prefabricat.ed housing modules, partition, toilet and shower .cubicles, flooring and ceiling. It can be drilled, screwed, nailed, machine sanded and glued to itself or wood. Furthermore, it can be plastered, painted, tiled or laminated with decorative plastic sheet to give a wide range of finishes (Magallanes 1982).

The potential of red la uan sa wmilling wastes for wood cement board manufacture was studied by Generalla and Eusebio (1984). The effects of several production variables such as board density, cement-wood ratio, amount of water, type and concen tra ti on of chemical accelerator, and pressing/clamping period were determined. Results of tests indicated that increasing the board density affected the board's MOR, but did not significantly affect its internal bond, thickness swelling and resistance to nail head pull-through. Stron.g woodcement boards were obtained at 70/30 cement-wood ratio, 600/o water and 30% calcium chloride.

Objectives

I. To evaluate the machining and

47

jointing properties and service characteristics of WWCBs.

2. l'o determine the suitability of WWCBs · as raw materials for fabricating kitchen and laboratory furniture.

3. To produce prototype modular kitchen/laboratory cabinets out of WWCBs and determine. cost, quality and serviceability relative to similar products from other wood-based panels.


Materials

The following WWCBs manufactured at the FPRDI Particleboard Pilot Plant were used as test samples for the study:

BOARD BOARD BOARD LENGiH THICKNESS DENSITY AND WIDTH

10 nm 500 kg/m3 920 x 1820 nm 20 nm - do - - do -30 nm - do - - do -50 nm 400 kg/m3 - do -

Test specimens were prepared from WWCBs following the cutting diagram in Figure 1. Fifty 100x900 mm specimens were prepared for the planing test. For the boring, mortising, shaping and routing tests, 50 specimens measuring 75x300 mm were prepared. Machining tests were conducted in accordance with ASTM Standard Designation D-1666, with some modifications to suit prevailing conditions at the Institute.

A total of 480 specimens with 60x60 mm dimension were prepared for the jointing tests. Two types of adhesives, polyvinyl acetate (PV AC) - based glue and portland cement, were used for the join ts. Common wire nails, wood

48 - ·~-- .. - . ~- ·- ...

A

A

A B II 19

A . A A A A A

A

f 8 B 8 B

B

II '•

8

~

Figure 1. Size and cutting diagram of test 19ieces. A: planing test (JO x 90 cm); B: boring. mortising and routing tests (7.5 x 30 cm).

screw, wooden dowels and spline were used as fasteners or joint reinforcements. Five specimens per joint type were prepared and tested per adhesive-fastener combination. Seventy-five tangile specimens of the same dimensions were fabricated and tested. The values gathered from the tangile specimens served as bases for comparison of joint strength and characteristic failure for the corresponding WWCB joints.

Machining Properties

Table sawing. A conventional saw at constant speed was used to cut the boards into 75x300 mm 'Pieces. Two types of carbide-tipped blades were used: one designed for cutting lumber and the other for cutting concrete. The saw cuts made while cutting the boards into smaller specimens . were classified and graded based on the degree of occurrence of machining defects in the specified surface area.

The following numerical rating system

used by FPRDI in grading machining tests of conventional lumber was applied to the s·pecimens.

Rating Descri12tion Percentage

defect-free area

1 Excellent 100 2 Good 90-99 3 Fair 80-89 4 Poor 70-79 5 Very Poor 69 and below

The same rating system was applied in grading the response of specimens to the succeeding tests on other ma.chining processes.

Planing. A single side surface planer with four high speed steel Jmives mounted on a cutterhead and running at 400 rpm was used to plane the individual specimens. · A feed rate of 17.78 cm per second was kept constant throughout the test. Samples were planed individually using three levels of cutting angles and · two levels of depth of cut. Planed surfaces were evafuated in terms of raised grain and rough cut arising.

Boring. A vertically oriented· single spindle electric drill ·with 25.40 mm diameter single-twist solid center bradpoint type bit was used. Three levels of spindle speed were used:

• 1190, 1900 and 3100 rpm. A jig. clamped on the drill press table allowed the specimen to be mounted and slid from side to side to bore a hole rfear each end of the specimen. The holes were bored completely through the specimens.

Mortising. The same equipment in the boring test was also used for mortising except that a 12.70-mm fixed hollow chisel mortiser and bit were added. The specimens in the boring test were also used in this test. Two mortises were made on each specimen. The defects considered in grading the mortise were crushing, tearing and general smoothness of cut.

Routing. A high-speed router of the stationary type was used. The highspeed steel auger bit was 6 mm in diameter with the speed kept at 10,000 rpm. The cut made ran parallel to the full length of the specimens. A fence guide was used to arrest the movement of the specimen during the cutting

Type of Joint/Board

Thickness Nail

Butt I 10 nm 1 inch 20nm 1 1/2 inches 30 nm 2 inches SO nm 3 inches

Miter I 10 nm inch 20 nm 1/2 inches 30 nm 1/2 inches SO nm 2 inches.

Rabbet I 10 nm inch 20 nm inch 30 nm 1/2 inches SO nm 2 inches

49

process. The resulting surface was examined visually and graded for breakouts9 sharp corners, chippings, fuzzy edges and general smoothness of cut.

Jointing Properties

The performance of butt, miter and rabbet joints of WWCB in cantilever loading was evaluated. The selected loading system simulated what was expected in actual service. Different types of fasteners shown below were used separately for the joint assembly.

Two each of the fasteners were used for assembly. A mixture of cement and PVAC at a 50:50 ratio served as binder for the joints with a curing period of 4 hr.

Butt joints. Side-to-end butting was studied. The strength of 60-mm wide WWCB was evaluated using: 1. basic plain glue, 2. glue and nail, 3. glue and screw, 4. glue and dowel, and 5. glue and spline joint systems. Except for the spline which ran across the joint, the test joints had single stiffener centrally driven into the joint. Stiffener penetration was controlled

Screw Dowel

1 inch 1/4 inch (.

2 inches · do · 2 inches · do · 3 inches 1/4 inch j

1/2 inch none 1 1/2 inches 1/4 inch p 1 1/2 inches • do •

2 inches • do •

1/2 inch none 1 inch 1/4 inch I 1 1/2 inches · do · 2 inches • do •

so

and kept constant for all stiffener types.

Five specimens of the joint. systems were fabricated. The specimens were taken at random from the boards prepared for the experiment.

In the absence of testing standards and gadgets, a mechanical vise held and joined the specimens during loading. After assembly and allowing the fastener to set for 2 weeks, the joint strength was tested using the Universal Testing Machine.

Miter and rabbet joints. Miter and rabbet joints of the same treatments as in butt joints were prepared and tested.

Data were analyzed using ANOVA in completely r:mdomized design for the effect of the different stiffeners on the strength of the basic glued joints. Comparison of treatment me~ns was done to establish the differences between means.

Physical and Mechanical Properties. Test

Twenty-five test specimens measuring 3x 10x50 cm were prepared from other boards and tested for bending properties. An·other 25 specimens were prepared and subjected to physical property tests. The data determined the effects of plastering the boards.

Paintability

The effect of accelerated weathering on the· performance of paint system applied· on unplastered/untiled WWCB measuring 17. 7 x6 cm was evaluated. Two coats of interior flat white paint were applied on the boards. Boards were exposed continuously for 15 hr to alternate wetting and drying inside a weather-a-meter. Weight was determined every 5 hr.

Assembly of Prototype Furniture

The optimum results gathered from the machining and join ting properties, bending strength ·and dimensional stability of raw, tiled and plastered . WWCBs, ·and paintability of the boards were the criteria used in determining their suitability as kitchen furniture.

Design of prototype was made prior to fabrication. The fabricated furnifure is being service- tested at FPRDI.

RESULTS AND DISCUSSIONS

Results of machining and join ting tests. on WWCB are presented in Tables 1 to 3.

Machining Properties

Planing. After planing two specimens using three cutting angles and two depths of cut~ the process was discontinued. The cement binder of the board affected the planer knives as big and numerous nicks readily developed on the cutting edges.

Sawing. Twelve out of 20 test boards showed excellent cutting quality for 30-mm thick boards. In 10-, 20- and 50-mm thick boards, all test pieces showed excellent cutting quaHty. Using an ordinary carbide sawblade, 17 out of 20 test boards for 30-mm, 9 out of 10 test boards for 10-mm, and 8 out of 10 for 20-mm and 50-mm thick boards showed . excellent cutting quality. The rest of the specimens for the two sawblade trials had slight machining defects such as slivers or uncut strands and some chipping off.

Boring. Table 2 shows the behavior of the test pieces to boring at different spindle speeds. The mean grades of the bores drilled at different speed levels (1.0-1.03) were excellent for 10-mm, 20-mm and 50-mm thick boards. For 30-

Table 1. Relative classification of machining properties of WWCB

MACHINING PROPERTIES/CLASSIFICATION OF BOARDS BOARD THICKNESS/ SAWING BORING MORTISING NO. OF SAMPLES TYPE OF BLADE SPINDLE SPEED, rpm

10-nm 1 2 3 4 5 6 7 8 9

10 MEAN GRADE

20-nm 1 2 3 4 5 6 7 8 9

10 MEAN GRADE

30-nm 1 2 3 4 5 6

'7 8 9

10 11 12 13 14 15 16 17 18 19 20

MEAN GRADE

50-nm 1 2 3 4 5 6 7 8 9

10 MEAN GRADE

Concrete Ordinary 1100 1900 3100

1 1 1 1 1 1 1 1 1 1 1.0

1 1 1 1 1 1 1 1 1 1 1.0

2 1 1 1 1 1 1 1 2 1 1 2 2 1 1 2 1 2 2 1 1.35

1 2 1 1 1 2 1 1 1 1 1.20

1 1 1 1 2 1 1 1 1 1 1.10

1 2 1 1 1 1 1 1 2 1 1.20

1 1 1 2 1 1 1 1 1 1 1 1 1 1 1 1 1 1 2 2 1.15

1 1 1 1 1 1 1 1 1 1 1-.0

1 1 1 1 1 1 1 1 1 1 1.0

1 1 2 1 1 1 1 1 1 1 1.10

2 2 3 2 1 1 1 3 2 1 3 2 1 3 3 1 2 1 1 2 1.85

1 1 1 1 1 1 1 1 1 1 1.0

1 1 1 1 1 1 1 1 1 1 1.0

1 1 1 1 1 1 1 1 1 1 1.0

1 1 1 1 3 3 2 2 2 2 3 2 2 2 2 2 2 2 2 3 2

1 1 1 1 1 1 1 1 1 1 1.0

1 1 1 1 1 1 1 1 1 1 1.0

1 1 1 1 1 1 1 1 1 1 1.0

2 2 2 2 2 2 2 2 2 2 1 1 1 2 2 2 3 1 1 1 1.75

1 1 1 1 1 1 1 1 1 1 1.0

2 1 2 2

. 1 1 2 1 3 1 1.60

2 1 1 2 1 1 1 1 1 1 1.20

1 1 2 1 1 2 2 2 2 2 3 4 1 1 2 1 1 1 2 3 1.75

1 1 1 1 1 1 1 1 1 1 1.0

ROUTING

1 1 1 1 1 1 1 1 1 1 1.10

1 1 , 1 1 1 1 1 1 1 1.0

2 2 1 1 2 2 2 2 2 2 2 2 2 1 1 2 1 3 2 3 1.9

1 1 1 1 1 1 1 1 1 1 1.0

Legend: Grade 1 - Excellent, Grade 2 - Good, Grade 3 - Fair, Grade 4 - Poor, Grade 5 - Very Poor

52

Table 2. Results of machining tests based.on the percentage of defect-free area

BOARD TH!CICNESS/ NO. OF DEFECT·FREE GOOD FAIR POOR VERY POOR TYPE/ICIND·OF TEST SAMPLES GRADE 1 GRADE 2 GRADE 3 GRADE 4 GRADE 5

(%) <X> CX> (%) (%)

A. 'Sawing

1. Concrete type blade

a. 10-nm 10 100 b. 20·nm 10 100 c. 30·nm 20 65 35 d. 50·nm 10 80 20

2. Ordinary blade

a. 10·nm 10 90 10 b. 20·nm 10 80 20 c. 30·nm 20 85 15 d. 50·nm 10 100

B. Boring

1. Spindle speed ·1100 rpm

a. 10·nm 10 100 b. 20·nm 10 90 10 c. 30·nm 20 40 . 35 25 d. 50·nm 10 100


a. 10·nm 10 100 b. 20·nm 10 100 c. 30·nm 20 20 60 20 d. 50·nm 10 100


a. 10·nm 10 100 b. 20·nm 10 100 c. 30·nm 20 30 65 5 d. 50·nm 10 100

c. Mortising

a. 10·nm 10 50 40 10 b. 20·nm 10 80 20 c. 30;.nm 20 45 40 10 5 d. 50·nm 10 100

D. Routing

•• 10·• 10 100 b. 20·nm 10 100 c. 30·nm 20 20 70 10 d. 50·nm 10 100

inm thick boards the mean grade was good (1.75-2). Qualitywise, the bores were 90-9-9% defect free. It was observed that the machining defect was due to loose cement and wood adhesion or separation of the board.

Mortising. Samples in the boring test were also used in this test. Visual inspection of mortise made revealed that the most severe machining defect was crushing of fibers .. Seventeen out of 20 test pieces had acceptable mortising properties and surface quality for 30-mm thick boards. For 10-mm thick boards, 9 out of 10 test pieces had acceptable mortising property, and for 20-mm and 50-mm thick boards, all.

Routing. Generally, the boards were rated good to excellent. Two test pieces from 30-mm thick boards were graded 3 due to burns that occurred on the board, crushing of the excelsior and raised fibers. Defects occurred on the part of the board found to have loose excelsior throughout.

The cutting edges of non-carbide knives and bits used in the sawing, boring, mortising and routing tests dulled easily and required frequent sharpening.

Jointing Properties

Butt joints. The common type of failure that developed in butt joints was board failure or separation of board. However, for 10-mm thick boards only one specimen with a fastener of glue and screw showed glue failure. For 20-mm thick boards two specimens with glue and screw

. combination had glue failure. No incidence of joint failure was noted along the glued joint on 30-mm and 50-mm .thick boards. This indicates that the joint formed with the glue-cement mixture was stronger than the board

53

itself and that boards could be satisfactorily butt jointed with a 50-50 PV AC-cement combination and stiffened with fasteners included in the experiments.

The average ~aximum strength value of 7.86 kg/cm was attained in glue and nail combination as joint fasteners on 50-mm thick boards. The corresponding values for th~ glue and screw on 50-mm and 30-mm thic~ boards were 7.19 and 7.11 kg/cm respectively (Table 3).

Miter joints. The combination of glue and screw as joirit fasteners gave th~ highest strength value of 9.60 kg/cm in miter joints on 50-mm thick boards. Failure also occurred on the boards.

This again indicates that the joint structure was stronger than the composite WWCB.

The joint fasteners used in 50-mm thick boards produced the higher strength value compared to the 10-, 20-and 30-mm thick boards.

Two test pieces each of 50-mm and I 0-mm thick boards showed glue failure.

Rabbet joints. The type of failure that developed on glue and dowel joint fasteners was shearing of dowel. It was accompanied by fastener failure and enlargem.en t of the bore. This suggests that the board was stronger than the dowels or fasteners. Board failure or separation of the board occurred on the other joint fasteners.

Joints fastened with glue and nail ~ave the highest value of 10.41 kg/cm on 50-mm thick boards. These were followed by glue and dowel wit~ values of 9.51 and 8.83 kg/cm respectively on 30-mm thick boards.

Glue and dowel joint fasteners on 10-mm thick boards were not tested.

54

Table 3. Average results of jointing properties of various WWCB using different joint fasteners, including tangile wood as control

GLUE GLUE AND NAIL

A. Woodwool·cement board

1. 1

• • k I 2 Butt JOtnts, g cm

a. 10-mm 0.35 0.63 b. 20-nm 0.79 2.51 c. 30-mm 5.10 6.64 d. 50-mm 3.63 7.86

2. Miter joints, kg/cm2

a. 10-mm 1.08 0.24 b. 20-mm 1.25 1.40 c. 30~nm 3.60 4.70 d 50-mm 9.13 8.24

3. Rabbet joints, kg/cm 2

a. 10-mm 1.04 0.9P b. 20-mm 1.88 2.63 c. 30-mm 4.50 6.28 d. 50-mm 4.17 10.41

B. Tang il e wood

1. Butt joints, kg/cm2 18.44 17.92 2. . . . k I 2 14.27 13.54 Mtter JOtnts, g cm 3. Rabbet joints, kg/cm2 17.01 17.64

Dowels with 1/4-inch diameter could not fit the board be~ause of its bigger size. They were excluded in statistical analysis.

Results showed that as the board became thicker, the strength values also increased. Economicwise, the 30-mm thick board was found optimum for fabricating kitchen cabinet modules.

The ANOVA results revealed that

JOINT FASTENERS

GLUE AND SCREW GLUE AND DOWEL GLUE·AND SPLINE

0.70 0.38 2.98 1.97 1.49 7.11 6.79 4.82 7. ,9 5.30 5.59

0.78 0.62 1.74 2.13 0.99 3.33 3.02 3.30 9.60 5.76 8.62

0.58 0.92 2.60 2.03 2.83 9.51 8.83 6.70 6.36 6.04 3.63

19.24 17.42 18.15 13.88 12.69 10.72 20.10 22.77 17.32

different thicknesses of the board and types of fasteners had significant effects on the jointing properties of WWCB (Table 4). The type of joints exhibited no significant effect on the join ting properties.

In multiple comparison of means of joint strength~ it appeared that 30-mm and 50-mm thick boards with rabbet and butt joints were in the same class (Table 5). This indicates that butt u.d

rabbet joints were suitable for producing relatively strong woodwool cement panel joints on 30-mm and 50-mm thick boards.

Table 5 also shows the inferiority of 10-mm and 20-mm thick panels compared to the 30-mm and 50-mm thick boards.

The effect of fastener addition to the basic glued joint was also demonstrated in Table 5. Strength significantly improved with the addition of fasteners.

Physical and Mechanical Test of Boards

Only the 30-mm thick boards were subjected to physical and mechanical tests as well as paintability test since

55

these were used in fabricating the prototypes. The boards also showed optimum results in laboratory scale at the FPRDI-Particleboard Pilot Plant as per recommendation.

Bending properties. The boards' MOR was determined using a Universal Testing machine. Table 6 shows the average MOR value of plastered and tiled boards,. boards plastered with combination of P.VAC and cement, and the control boards.

The strength of the basic WWCB in bending appeared to improve with the addition of overlaying plaster and tiles. The thicker the overlay, the stiffer the board became. When used as kitchen cabinets, plastering and overlaying with tiles will, therefore, improve the strength of the component panels.

Table 4. ANOVA results of the effect of board thickness, type of fasteners and join ts on the join ting prop~rties of WWCB

SOURCE OF VARIATION

A B c

AB AC BC ABC ERROR TOTAL

LEGEND:

DF

3 3 2 9 6 6

18 182 229

SUM OF MEAN SQUARES SQUARES

1458.853 486.28 77.270 25.76 7.444 3.72

76.965 8.55 204.686 34;1 l 35.962 5.99

115.074 6.39 586.829 3.22

2563.084

A - Different thickness of Woodwool-cement Boards B - Type of Fasteners C - Type of join ts **- Significant at 1 % significance level *- Significant at 5% significance level

ns- Not significant

F-VALUE

** 150.82**

7.99 1.15*ns 2.65**

10.58 l.86ns l.98ns

56

Table 5. DMRT results of the effect.of board thickness, various fasteners and type of joints on the jointing properties of WWCBs

TREATMENT/PROPERTIES MEAN

Legend: A1 = A2 =

:3 = =

84 = 81 = 82 = 83 = 4

0.76 a 1.97 b 5.48 c 6.98 d 3.08 b 4.37 a 4.46 a 3.52 b 8.906 a 7.584 ab 6.651 be 5.945 cd 5.875 cd 5.642 cde 4.967 de 4.428 e 2.491 f 2.178 f

10 nm thick boards 20 nm thick boards 30 nm thick boards 50 nm thick boards Glue Fastener Glue and Nail Fastener Glue and Screw Fastener Blue and Spline

TREATMENT/PROPERTIES MEAN

1.893 fg 1.313 fg 0.823 g 0.819 g 0.699 g 0.672 g 8.-860 a 6.788 b 6.141 b 5.974 b

5.920 b 3.732 c 2.488 d 1.942 ~ 1.372 ef 0.882 ef 0.847 ef 0.532 f

c1 = Butt joints C = Miter joints

c..2 = Rabbet joints i = Significant at 5% significance level ns = not significant

Table 6. Average modulus of rupture of WWCB plaster~d and overlaid with tiles.

WOODWOOL CEMENT BOARDS

Boards with 1/4-inch plaster Boards with 1/2-inch pJaster Boards with combination of glue and

cement as plaster Boards overlaid, with tiles Control bbards

MODULUS Of RUPTURE kg/cm

32 52 50

62 24

57

Table 7. Average water absorption, thickness swelling and linear expansion of WCB at various tfme of water inmersion

WOODWOOL·CEMENT TIME OF WATER BOARDS IMMERSION;

hr.

1. Boards with 1/4·inch 24 plaster 120

192 264 360

2. Boards with 1/2·inch 24 plaster 1ZO

192 264 360

3. Boards with cod>ination 24 of glue and cement as 120 plaster 192

264 360

4. Boards overlaid with 24 tiles 120

192 264 360

5. CC>ntrol boards 24 120 192 264 360

Physical prooerties. The thickness swelling (TS), linear expansion (LE) and water absorption (WA) of the raw boards obtained from various duratiOn of water immersion are shown in Table 7.

TS, LE. and WA were expressed as percentages of the original weight, thickness, length and width. With an

THICKNESS WATER LINEAR SWELLING, ABSORPTION .EXPANSION

" " " 0 30 0.11 0.35 31 0.75 0.40 30 0.90 1.38 32 0.13 1.64 34 0.09

0.47 25 0.37 0.20 26 0 .• 40 0.82 26 0.49 0.90 28 0.80 1.00 28 0.77

1.04 24 0.37 0.34 24 0.40 0.85 25 0.49 0.66 26 0.80 0.90 27 0.77

1.48 21 Q.05 0.92 22 0.07 0.69 22 o~ 10 0.48 19 0.62 1.10 25 0.67

1.62 42 0 1.14 43 1.11 1 .01 49 0.91 0.67 52 0.76 0.95 49 0.68

increase m duratfon of water immersion · from 24 to 360 hr, the changes in TS, LE and WA were minimal. No delamina ti on of board occurred in all samples even for . 360 hr of continuou.s immersion.

The results indicate an improvement in the dimensional stability of the board with the addition of overlaying

58

Table 8. Effect of accelerated weathering on the performance of paint system applied on WWCB

PERFORMANCE VALUES, % Appearance Integrity Protection Average

77.03 78.31 85 80.11

Numerical Equivalent: Good - 100%, Fair - 75%, Poor - 50%, Bad - 25%

Table 9. Preparation of estimated materials and labor and total cost of WWCB kitchen-cabinet

MATERIALS AND LABOR QUANTITY COST/UNIT TOTAL COST

Woodwool-cement Boards a. 30-rrm thick 5 panels P180/panel p 900.00 b. 20-rrm thick 3 panels 127/panel 381.00 Cement 2 bags · 85/bag 170.00 Glue 1/2 gal 195/gal 97.50 Lumber a. 1 )C 4 X 14 1 pc 17/bd ft 79.35 b. 1 x 1 x 16 1 pc 48/pc 48.00 c. 2 x 3 x 10 2 pcs 15/bd ft 150.00 Hinges 10 pcs 3.50/pc 35.00 Handle 5 pcs 7.50/pc 48.75 Catches 10 pcs 2.50/pc 25.0 Ti Les 145 pcs 2.50/pc 362.50 Capping CTi Les) 74 pcs 4.20/pc 310.80 Sink (18 x 30)1 pc. 320/pc 785.00/pc 785.00 White Cement 1/2 kg 15.00/k 7.50 Nail a. 1 1/2 1/4 kg 26/k 6.50 b. 2 1/2 1 kg 26/k 26.00 Screw, 2 1/2 70 pc~ 0.50/~c 3.50 Sand 1/4 m 180/m 45.00 Paint 1 Quart 65/Qt 65.00 Tinting Color 1 Tube (60 ml) 24/Tube 24.00 Labor (Fabrication) a. One Carpenter Five Working Days 135/day 675.00 b. One Mason - do • 125/day 625.00

TOTAL COST P4,870.40

materials on the surface of the basic board. The board was relatively stable dimensionally in the presence of moisture compared to solid wood.

Paintability

The performance ratings of ·the painted boards taken after 15 hr of exposure are presented in Table 8. The average performance value was 80.12%. which is fair to good.

Accelerated weathering was terminated after 15 hr due to significant reduction in general appearance and discoloration under appearance ratings and evidences of chalking, checking, cracking, peeling and erosion which affected the integrity values. The appearance of a dirty white color and paint thinning out or loss over peaks of wood components were observed .after exposure. This indicates that the board in its raw form may not provide a suitable surface for paint application.

Design and Fabrication of Prototypes

Four moduies constituted the prototype kitchen cabinet.

In the construction of joints for the prototype, the combinations of glue and screw and glue and nail· were used as joint reinforcement. The plaster was 1 /2-inch thiCk and the top of the cabinet was overlaid wLth tiies.

Prototypes were similar to the concrete type of kitchen cabinets. Producers must use t-heir ingenuity to adopt tools and methods to work on this type .of board. However, boards should be cut exactly according to the given dimensions because these were found to be generally unsuitable for planing.

The average cost of producing a WWCB cabinet is P4,870.40. The same size of cabinet from concrete costs P6,442.95

59

based on 1991 .prices. Cost analysis showed that the former cost 24.4% less to produce than the latter. Breakdown of materials and labor are shown in Ta bl es 9 and 10.

Service Peformance of Kitchen Cabinet

One unit was installed at the FPRDI WWCB Model House and another at one of the FPRDI laboratories for servicetesting. Inspection and evaluation have been conducted every 3 . months thereafter.

Evaluation was done through measurements of the thickness, length and width of the fabricated kitchen cabinet. No change on the dimensions based on initial measurements and de lamina ti on occurred.

CONCLUSIONS

Planing the WWCBs is not advisable.

WWCBs can be suitably sawn using ordinary carbide sa wblade.

. Boring and mortising characteristics of WWCBs fall between "good" and "excellent".

Routing properties of WWCBs range from "excellent".

the sample "fair" -to

. WWCBs can be machined into thinner on thicker boards.

. In jointing, the 30 mm- and 50 mmthick boards give the· highest values in all types of joints and fasteners.

Butt and rabbet joints are found desirable for WWCBs.

The MOR increases in WWCBs plastered and overlaid with tiles.

60

Table 10. Breakdown of estimated materials and labor and total cost of concrete-type kitchen cabinet

MATERIALS AND LABOR QUANTITY COST/UNIT TOTAL COST

Hollow Blocks (4x&x16) 24 pcs P3.20/pc p 76.80 Cement 3 bags 85/bag 255.00 Iron Bar (3/8 x 20) 6 -pcs 17.50/pc 175.00 Conmon Wire, No. 18 1/2 kg 35/kg 17.50 Sink 918 x 30) 1 pc 785.00/pc 785.00 Nail, 2 1/211 1. kg 26.00/kg 26.00 Plywood, 3/4 thickness 3 panels 680/pc 2040.00 Hinges, 1 1/2 x 3 10 pcs 3.50/pc 35.00 Handle 5 pcs 7.50/pc 37.50 Catches 10 pcs 2.50/pc 25.00 Tiles ·145 pcs 2.50/pc 362.50 Capping 74 pcs 4.20/pc 310.00 White cement 1/2 kg 15.00/kg 7.50 Paint 1 qt 65.00/qt 65.00 Tinting color 1 tube (60 ml> 24.00/tube 24~00

Lurber 0 1 x 4 x 14 1 pc 17.00/bd ft 79.35

.o 1 x 1 x 16 1 pc 48.00/pc 48.00 0 2 x 3 x 10 2 pcs 15/bd ft 150.00

Nail, 1 1/2 1/2 k! 26/k 13.00 Sand 1.5 m 180Jm3 90.00 Labor (Fabrication) o One Carpenter Seven working days 135/day 945.00 o One Mason • do ·

TOTAL COST

. WWCBs are found dimensionally stable when plastered and overlaid with tiles.

. Failure of paints applied on raw WWCBs occurs at an accelerated pace.

. The WWCB cabinet costs 24.4% less than a similar cabinet made of concrete.

RECOMMEND A TIO NS

. When sawing, boring, mortising and

125/day ~

P6,442.95

routing WWCB, the conventional tools should alw.ays be sharp.

. The effect of keyhole cutting using keyhole saw and bradpoint type bit should be studied.

A combination of glue and screw and glue and nail should be recommended as joint fasteners in all tyP.es of jointing system.

. Boards 30-mm thick are potential materials as manifested by the results in the substantial machining and testing properties.

. Plastering and overlaying with tiles should be d.one when fabricating kitchen cabinets.

Plastering of surface before pain ting is recommended.

Gloss or enamel type of paint is recommended · for unplastered

REFERENCES

61

surface.

In commercial production, manufacturers. should use carbide cutting ~lade for facility in processing.

Technology is ready for piloting and economic studies.

FLYNN, G. and A. HAWKES. 1980. An industrial profile of woodwool-cement slab manufacture. Tropical Products Institute. London. July issue.

FRASER, H.R. 1977. Cement board finds part acceptance. World Wood. March: 11-13.

GENERALLA, N.C. and D.A. EUSEBIO. 1984. Studies on the manufacture of wood-cement boards using red- lauan woodwastes. Unpubl. Report. FPRDI Library, College, Laguna.

MAGALLANES, R. 1982. All purpose building board. Construction. June 21, 1982:8.

AMERICAN SOCIETY FOR TESTING AND MATERIALS. D. 1964. Book of ASTM Standards, Philadelphia, Pa., USA.

1966. Book of ASTM Standard~ Philadelphia, Pa., USA.

62

VARIATION IN BENDING STRENGTH PROPERTIES OF GLUED-LAMINATED COCONUT WOOD

. Felix B. Tamolang 1

Variations in strength properties were determined in solid and 3-layered g/uedlaminated cocowood representing the butt, middle and top portions of five 70-year old coconut palm trees. Treatments used were: a. four types of 3-layered configuration i.e., hard-hard-hard, hard-soft-hard, soft-hard-soft, and soft-soft-soft; and b. three different types of glues as bonding materials i.e., weldwood, urea formaldehyde and phenol resorcinol. Air-dried solid and glued-laminated cocowood specimens were tested under static bending. The values of modulus of rupture (MOR), fiber stress at elastic limit (FSEL) and modulus of elasticity (MOE) were determined.

Statisticai analysis showed that MOR, FSEL, MOE and relative density of all the specimens decreased appreciably from the butt to the top and from the outer hard to the inner soft portion of the tree. Moreover, the strength properties of glued-laminated cocowood specimens within the hard-hard-hll(d and hard-soft-hard configurations were comparable with solid hard cocowood irrespective of the glue used. This indicates that the utility of cocowood can be expanded by glue-lamination technique.

INTRODUCTION

Coconut (Cocos nucifera Linn.) has been called the "tree of life" because of its multifarious uses, particularly the fruits and the leaves. The former gives meat, fresh water, oil, husk, coir dust, shell among others. The latter can be converted into fuel, brooms, toothpicks and novelties. The trunk or stem has been found useful for construction, pulp and paper, particleboard, novelties, charcoal (Tamolang 1976) and woodwool cement board production (Tamolang 1980).

The decreasing supply of Philippine hard woods necessitates the increased use of other wood-protlucing species like the coconut. This is so considering the increased supply of coco lumber as a result Qf the ·coconut replanting program of the Philippine government.

Full utilization of the coco stem will help conserve the for est resources of the country.

Objec~ives

1. To promote the increased utilization of coco wood using glue lamination techniques.

2. To determine the variation in the bending properties of the gluedlamina ted butt, middle and top portions of the stem.

REVIEW OF LITERATURE

A preliminary study by the Forest Products Research and Development Institute (FPRDI) using five samples of

1 Senior Science Research Specialist, Housing and Materials Research Division. Forest Products Research and Development Institute, College, Laguna 403 l.

three-layered glued-laminated beams using phenol resorcinol as binder (Tamolang 1979) compared the average strength . properties of coconut laminated beams (CLB) and the solid wood of some conventional Philippine timber species. It was found that:

. CLB was superior to apitong (Dipterocarpus grandijlorus Blco.) by 16% in FSEL, about equal in MOR, but inferior by 21% in MOE.

CLB was superior to guijo (Shorea guiso Blume) by 11 % in FSEL, about equal in MOR, and superior by 17% in MOE.

. CLB was slightly inferior to yakalgisok (Shorea gisok Foxw.) by 7% in FSEL but inferior by 19% and 43% in MOR and MOE respectively.

. CLB was superior to molave (Vitex parviflora Juss.) in all respects, i.e., FSEL, MOR and MOE by 17%, 3% and 5% respectively.

In New Zealand, McLaughlan (1974) studied the glued joints of coco timber bonded with resorcinol adhesive and cured by radio frequency heating under ambient temperature. Results showed that shear strength in the glueline was highly correlated with wood density and good adhesion betweeen the · glue and the wood, particularly the soft tissue between the hard fibers. The strength of the glued join ts was found to be related primarily to. the wood structure. This means that coco timber boards can be glued together wide face-to-wide face, but high strength joints are unlikely to be obtained when gluing boards end-toend either with a scarf joint or a finger joint.

Wilson (1939) cited some advantages and disadvantages of glued-laminated

63

construction. Among the advantages are:

Fa brica ti on of long arches for use over areas of large and unobstructed fashion, such as arches with a span of over 457 m.

. Utilization of relatively small pieces which permit rapid and uniform drying. This minimizes shrinkage and the con co mi tan t warping and twisting.

. Fabrication of members requiring large cross-sectional area and great lengths in the construction site using smaller-sized units which can be easily shipped.

. Sorting of laminate and its strategic placement in between the memb'ers to provide maximum strength where needed. Also, lamination of different kinds of wood with different quality and density can be incorporated into the members to ensure that strength requirements are met.

Fabrication of members with relatively small radii of curvature without excessive cross grain. Cross grain is produced when the curved piece to be shaped forms a single plank.

. Simplified join ts design of laminated curve-truss-chord members which are continuous through several panels.

. Chambering of laminated beams to counteract sag.

. Construction of economical grai:ef ul -looking beams requiring constant stress throughout its span as to the stock needed in their fabric~tion.

. Less deterioration of gluedlaminated members when exposed to

64

chemicals compared to metal structures or wooden members with metal fastenings.

On the other hand, the disadvantages include:

Higher cost of glued-laminated products for construction compared to other f Orms.

. Unsuitability of glued-laminated products for construction which must be completed within 2 or 3 weeks after the lumber is cut from the log.

. The need for skilled workmanship and careful manipulation during 3:Ssembly to ensure maximum service.

Wilson and Cottingham ( 1947) tested glued-laminated wood beams and columns and concluded that: a. the number and thickness of laminated wood beams do not significantly affect the strength of horizontally laminated beams, and b. scarf joints with slopes not steeper than 1 :5 can be permitted in laminations on the compression side of the lower side of a beam without detriment to strength.

Nishihara and Sugano ( 1962), in their studies on laminated wood of akamatsu (Pinus densiflora Sieb. et Soc.), reported excellent bonds of casein glues for interior use.

MATERIALS.AND METHODS

Sampling Procedure

The sampling technique adopted was complete randomization. Because of time and resource constraints, only five healthy, 70-year old coconut trees were collected from Sta. Fe, Los Banos, Laguna. From each stem, 3.3 m logs were cut from the ·butt, middle and top (Fig. Ia). From each log, the hard

outer portion and the soft inner portion were longitudinally sawn into 64-mm thick flitches (Fig. 1 b).

From each flitch, four equal parts (85 cm long) were sawn for three separate adhesive/glue treatments, including the control (Fig. le).

Drying

All specimens were air-dried in drying sheds for 2 consecutive weeks using 19-mm stickers. Then these were kilndried for one month until the desired moisture content was attained.

All specimens were conditioned to· 15% MC.

Fabrication and Glue-Lamination

The 64-mm thick flitches were each sawn into 17-mm thick pieces and finished to represent three-layered, glued-laminated specimens with · dimensions of 51x51x762 mm. Each layer was smoothened, sorted and matched according to the type of laminated conf igura ti on to be assembled.

Forty-five specimens for each type of laminated configuration were as!;embled, making a total of 180 specimens. Fifteen samples each of solid soft and hard specimens representing the control mate~ials were fabricated into 51x51x762 mm standard dimensions for the static bending test.

The specimens were glued at 21.1°c room temperature at the Wood Lamina ti on Laboratory of FPROI. Standard procedures recommended by the glue manufacturers were strictly followed. The glue was uniformly applied on the contacting faces by double spreading. All glue-laminated specimens were subjected to a uniform pressure of 4.5 MPa for 8 hr in an 816-kg Laminated Pressing Machine.

Fltu,.. la• Position alono th• stem

T

B B B

Figure I b . IC Ind• of mot• r lala

Flour•

cutting dlaoram1 and labeillng of specimens

H· bard outer portion S • soft Inner port Ion

I c , Adbttlve I Glu~

+

·~ w \ p

I ~89cm I 8!5cm

W - materials for w•ldwood l•lnatlon P ·materials for ph•nol• reaorclnol U • 111aterlal1 for urea - formaldehJd• c ·material• for control 1peclmen1

3.3m

\ -.]

I

u

8!5cm

\ c

I I 85cm

Figure 1. Schematic diagram of the various treatment locations with respect to tree stem positions.

65

M

B

\ l

---I

.66

Testing

The tests fallowed the procedure set by the American Society for Testing Materials (ASTM) for testing small clear specimens of timber. The strength property observed was static bending. Dimensions were measured using a dial gauge with a sensitivity of .025 mm. The specimens were loaded centrally over two supporting knife edges. The supports were 70 cm apart, with the load direction parallel to the laminates.

The · load was applied continuously throughout the test at the middle of the span at 0.38 mm/min. Readings of deflections and .loads were taken simultaneously at a convenient increment until the specimens failed to support the load.

Different types of failure were observed after the test.

Load-Deflection Curve

The readings were plotted on a graph with the load on the vertical axis and the deflection on the horizontal axis.

Weight and Moisture Content

Specimens were weighed immediately before and after the tests. Moisture sections about 25 mm long were cut near the failure point and weighed prior to oven-drying at I03°C (±2) until a constant weight was attained.

Relative Density

The relative density of all specim.ens was determined using the weight and volume measurement method.

Properties Computed

The bending properties like MOR, FSEL, MOE and the relative density were computed. The bending

properties and relative density values of some Philippine hardwoods were adjusted to 15% MC using the Madison Exponential Formula (Wilson 1932):

Experimental Analysis

The Randomized Complete Block Design (RCBD) was employed to assess the variability in strength properties of both glued-laminated and solid specimens. The butt, middle and top of the coco stem represented the blocks.

Treatments consisted of: a. four types of three-layered configuration, i.e., hard-hard-hard (H-H-H), hard-softhard (H-S-H), soft-hard-soft (S-H-S) apd soft-soft-soft (S-S-S) specimens; and b. three types of glues as bonding mate.rials, i.e., weld wood, urea f~rmaldehyde and phenol resorcinol. Figure 2 shows the experimental layout of RCBD.

The Duncan's Multiple Range Test (DMR T) was used to partilion the treatment into groups such . that treatments belonging to a group did not significantly differ from each other.

Furthermore, a regression analysis was use to relate strength properties to each other.

RES UL TS AND DISCUSSION

Height and Diameter

Table 1 shows the height and diameter of the butt, middle and top of the five coconut trees. The heigh ts ranged from 11.04 m to 12.05 m, with a mean of 11.34 m. The average diameters of the discs obtained from the butt, middle and top were 294, 234 and 208 mm respectively.

The range of values for total height and diameter of the butt, middle and

67

s-s-s s-s-s s-s-s s-s-s s-s-s S·H·S S·H·S S·H·S S·H·S S·H·S

Block III en H·S·H H·S·H H·S·H H·S·H H·S·H H·H·H H·H·H H·H·H H·H·H H·H·H C·S C·S C·S c-s- C·S C·H C·H C·H C·H C·H

s-s-s S·S·S S·S·S S·S·S S·S·S S·H·S S·H·S S·H·S S·H·S S·H·S

Block II (M) H·S·H H·S·H H·S·H H·S·H H·S·H H·H·H H·H·H H·H·H H·H·H H·H·H C·S C·S C·S C·S C·S. C·H C·H C·H C·H C·H

S·S·S S·S·S S·S·S S·S·S S·S·S S·H·S S·H·S S·H·S S·H·S S·H·S

Block I CB) H·S·H H·S·H H·S·H H·S·H H·S·H H·H·H H·H·H H·H·H H·H·H H·H·H C·S C·S C·S C·S c-s C-H C·H C·H C-H C·H

Legend: Free Position Configuration.

B · Butt H·H-H = 3-tayered hard·hard·hard lamination H · Middle H·S·H = 3 layered hard-soft-hard lamination T · Top S·H·S = 3 layered soft-hard·soft lamination

s-s-s = 3 layered soft-soft-soft lamination

Control c-s = solid soft portion C-H = solid hard portion

Figure 2. The experimental layout of the RCB design.

top did not vary appreciably, suggesting a fairly good sampling of the trees.

Table 2 shows the average relative density values of the solid hard and soft portions of the butt, middle, and top. The relative density decreased markedly from butt to top for both the hard "outer" and the soft "inner" portions, with the former exhibiting sharper reduction. The relative density of the hard layer decreased from 0.612 to. 0.401, and that of the soft layer,

from 0.404 to 0.285. The decrease was linear for the hard layer and nonlinear for the soft layer (Fig. 3).

On the average, the hard outer layer exhibited about 1.35 times higher relative density than the soft portion. The density values for hard vs soft portions were as follows: 0.612 vs 0.404, 0.449 vs 0.393, 0.40 I vs 0.285 for the butt, middle and top respectively. The relative density of the soft layer at the butt (0.404) approximated that of the hard layer at the top (0.401), which

68

Table 1. Height and diameter of sample trees

TREE NO.

2 3 4 5

Average

Range

TOTAL HEIGHT (m) Bl.ltt

12.05 290 11.21 288 11.11 274 11.27 340 11.04 278

11.34 294

11.04·12.05 274·340

DIAMETER (nm)

Middle Top

238 211 252 222 215 205 242 208 210 195

234 208

215·252 195·222

Table 2~ Average relative density values of solid hard and soft portions of cocontit wood according · to height in the tree stem

TYPES OF WOOD MATERIAL

Solid hard portion Solid soft .portion

Butt

0.612 0.404

was also observed by Richolson ( 1977). The effect of the difference in relative densities between and among portions and among positions was reflected in the MOR values since strength was related to relative density up to a certain extent.

Table 3 shows the average MOR values among positions and among configurations of solid and laminated coco wood. The MOR values of solid hard and ·soft portions as well as gluedlaminated wood specimens varied from 8.6 MPa (weldwood, S-S-S top) to 62.2 MPa (solid hard wood, butt) with a mean value of 35.9 MPa. The coefficient of variation was computed tc be 12o/o (Table 6).

POSITION

Middle

0.499 0.393

Top

0.401 0.285

AVERAGE

0.504 0.361

Expectedly, there was a reduction. in strength from butt to top (Fig. 4). The MOR of the solid hard portion decreased linearly from 62.2 MPa (butt) to 27.6 MPa (top), while that of the solid soft portion decreased nonlinearly ·from 38.1 MPa (butt) to 1 l.8 MPa (top). The decrease in MOR from butt to top was higher for the hard portion. The result was similar to that obtained by Walford and Orman (1977), who worked on coconut logs from the Fiji islands.

Since the MOR decreased with height and distance from the outer portion (hard to soft), the stem may be partitioned for maximum utility· whenever possible and practicable. The

0]0

o.so

0.50

>-.I-Ch 0.40 z ILi 0

~ 0.30 ~ ct ...I w a: 0.20

0.10

0 5.0 6.0

< eutt) C Middle)

HEIGi-iT UP STEM {METERS)

Figure 3. Ef feet ·of stem position on the relative density of coco wood.

9.0 (Top)

70

..... 60 0 c.> tll 0 gee 0

:IE

ILi 40 a: ::> I-Q.

~ 30

IA. 0

Cl) 20 ~ .J ~ 0

~ 10

0

69

• Solid Hard Portion

O Solid Soft Portion

3.0 6.0 C Butt} (Middle}

HEIGHT UP STEM ( METERS)

9.0 (Top)

Figure 4. Ef feet of stem position on the strength of coco wood.

Table 3. Average MOR values CMPa) among stem height and among configurations of sol id and g_lued· laminated coconut wood

CONFIGURATION POSITION AVERAGE Butt Middle Top

Hard· Hard· Hard Urea formaldehyde 50.3 42.7 37.8 43.6 Weldwood 50.6 45.6 35.0 43.7 Phenol resorcinol 51.8 47.2 32.4 43.8 Solid hard wood 62.2 43.8 27.6 44.6

Soft·Soft·Soft Urea formaldehyde 32.2 31.2 12.9 25.5 Weldwood 30.5 24.1 8.6 21.1 Phenol resorcinol 26.2 24.2 15.3 21.9 Solid soft wood 38.1 30.0 11.8 26.6

Hard·Soft·Hard Urea formaldehyde 49.0 42.7 34.6 42.1 Weldwood 56.6 47.6 41.2 48.5 Phenol resorcinol 52.3 38.3 37.4 42.7

Soft·Hard·Soft Urea formaldehyde 33.0 35.1 26.1 31.4 Weldwood 40.4 36.7 24.3 33.8 Phenol resorcinol 42.4 29.8 29.3 33.8

70

str~mger butt portion may be utilized for medium construction, i.e., beams and rafters, while the middle portion may be used for light construction, i.e., sidings, panel cores and others.

Table 4 shows the average FSEL of solid and glued-laminated coco wood. The average FSEL ranged from 12.1 (phenol resorcinol, S-S-S) to 31. 7 MP a (phenol resorcinol, H-H-H). As in relative density and MOR, the FSEL for both solid hard and soft portions decreased sharply from butt to top.

The FSEL values of laminated H-H-H specimens was comparable to that of solid hard wood. Likewise, the FSEL values of the S-S-S specimens were comparable to those of solid soft wood.

Table 5 shows the average modulus of elasticity (MOE) values among positions and among configurations of solid and glued-laminated coco wood. The MOE values ranged from 1,200 MPa (solid soft wood, top) to 8,300 MPa (solid hard, butt), with an average of 5,100 MPa. The coefficient of variation wa$ 19.8%, slightly higher than that obtained for MOR. This indicates a greater degree of variation among specimens. in the case of MOR. As in MOR and FSEL, the MOE values decreased from butt to top for both hard and soft portions, with the decrease slightly higher for the hard portion (Fig. 5).

The MOE decreased linearly from 8,300 MPa (butt) to 3,400 (top) for the solid hard portion. It decreased non-linearly from' 4, 700 MPa to 1,200 MPa for the solid portion. The . ANOV A results were essen ti ally similar to those of MOR and FSEL. Stem positions within trees and among configurations were statistically significant, while treatments within configuration were statistically insignificant. Likewise, the effect of glue was not discernible. Within the H-H-H and the S-S-S

configurations, the . stiffness of laminated specimens was comparable to their respective controls (i.e., either hard or soft wood).

As in MOR, the H-H-H and H-S-H configurations were comparable to each other and were both significantly higher than the S-H-S and S-S-S specimens. This was expected since the two outer layers were stressed more than the middle layer. Between the two latter configurations, the S-H-S showed higher MOR values.

Tables 6 to 8 are summaries of the statistical analyses conducted. The DMR T was used to compare the different treatments.

Table 6 indicates the mean squares and statistical significance of stem positions and configurations for the various strength properties of solid and glued-

9.0] 8.Q

• Soll d Hard P ortl on

o Solid Soft Portion

g1.o 3 a. 0

:6.0 :E

0 0

~5.0 > 1-(j ~4.0 (/) <( ...J ILi

3.0 IL 0

(/)

32.0 :::> Q 0 :E

1.0

0 3.0 6.0 9.0 (Butt) (Middle) (Top)

HEIGHT UP STEM (METERS)

Figure 5. Ef feet of stem position on the stiffness of coco wood.

7l

Table 4. Average FSEL values (MPa) among tree stem positions and among configurations of solid and glued-laminated coco wood

CON FI GURA Tl ON POSITION AVERAGE Butt Middle Top

Hard-Hard-Hard Urea formaldehyde 37.9 30.4 12.2 26.8 Weldwood 24.4 24.0 16.3 21.6 Phenol resorctnol 43.6 32.4 19.2 31.7 Sol id hard wood 40.8 29.7 16.7 29.1

Soft-Soft·Soft Urea formaldehyde 19.6 16.2 6.0 14.0 Weldwood 20.3 17.0 5.7 14.3 Phenol resorcinol 15.1 11.8 9.5 12.1 Solid soft wood 23.8 20.4 8.1 17.4

Hard-Soft-Hard Urea formaldehyde 29.6 27.8 22.4 26.6 Weldwood 39.7 29.2 29.5 32.8 Phenol resorcinol 42.2 19.1 16.2 25.8

Soft-Hard-Soft Urea formaldehyde 18.0 18.5 10·.a 15.8 Weldwood 27.0 20.7 15.8 21.2 Phenol resorcinol 32.6 18.1 15 .1 21.9

Table 5. Average MOE values (1000 HPa) among tree stem positions and among configurations of solid and glued· laminated coco wood

CONFIGURATION POSITION AVERAGE Butt Middle Top

Hard· Hard-Hard Urea formaldehyde 8.1 6.0 3.6 5.9 Weldwood 7.7 8.6 3.9 6.7 Phenol resorcinol 7.1 5.8 3.9 5.6 Solid "ard wood 8.3 5.8 3.4 5.8

Soft· Soft-Soft Urea formaldehyde 4.8 4.5 1.8 3.7 Weldwood 4.4 3.7 1.4 3.2 Phenol resorcinol 3.3 4.7 2.6 3.5 Sol id soft wood 4.7 3.8 1.2 3.2

Hard~Soft·Hard Urea formaldehyde 8.2 5.7 4.8 6.2 ~eldwood 8.9 6.4 5.4 6.9 Pheno~ resorcinol 8.6 5.8 4.7 6.4

Soft· Hard-Soft Urea formaldehyde 4.4 4.6 4.1 4.4 Weldwood 5.3 7.4 3.7 5.5 Phenol resorcinol 5.2 4.0 4.3 4.7

/

72

Table 6. DMRT results of stem positions and configurations for the various strength properties of solid and glued· laminated coco wood -

SOURCES OF VARIATIONS Modulus of Rupture

CMPa)

** Positions (Butt, Middle, Top) 10719.7

** Treatments 2686.5

** Among configurations 11122 Within configurations 155.8ns

a. within Hard·Hard·Hard 5.7ns Solid hard wood vs. 11glued11 16.6ns Among 11glued11 0.29ns

b. Within Soft·Soft·Soft 221.3ns Solid soft wood vs. 11glued 337.4ns Among 11glued11 163.3ns

c. Within Hard·Soft·Hard 379ns

d. Within Soft·Hard·Soft 59.7

Error 189.7

Mean 35.9 CV 12.0

** Significant at 0.01 level ns Not significant

laminated coco wood. Significant differences were observed among the different configurations but not within configurations. As such, the values of the glued-laminated specimens within each configuration were comparable to each other. Comparison among glues within configuration showed no significant differences. This means that any of the three glues can be used with largely similar results.

As shown in Table 7, the means of the H-H-H and H-S-H configurations were comparable to each other (43.7 MPa vs 44.4 MPa ). Both, however, were markedly higher than S-H-S (33.0 MPa). The S-S-S configuration produced the lowest strength (22.8 MPa). The average MOR values of both H-H-H and H-S-H configurations were also

PROPERTY Fiber Stress at Modulus of Elastic Limit Elasticity

CMPa) (1000 MPa)

** ** 82868 315.4

** ** 1414.7 53.5

** ** 4883.3 ·213.8 374.1ns 5.4ns

568.7ns 7.4ns 124.7ns 1.3ns 790.7ns 10.4ns

149.4ns 1.9ns 363.4ns 1.4ns 42.7ns 2.1ns

449.2ns 3.6ns

344.5ns 9.7ns

210 10.3

22.2 5.1 20.4 19.8

comparable to the solid hard portion (44.6 MPa) (Table 8). These results imply that the utility of the coconut can be improved by laminating three thin-layered specimens of the H-S-H configuration with at least two of the three . layers being hard portions. If a soft portion is used, it should be at the middle, sandwiched between the two hard portions. The use of an S-H-S or S-S-S configuration drastically lowered the MOR to about 700/o of the solid hard portion in the case of S-H-"S and 50% for S-S-S. The values obtained for S-H-S, however, were still significantly higher than those of the solid soft portion. The relatively low MOR values (21.1 - 26.6 MPa) of S-H-S specimens limit their use on structures which do not require high MOR. Obviously, the S-S-S configuration is

Table 7. DMRT results of stem positions and configurations for the various strength properties of glued-laminated coco wood

PROPERTIES Modulus of Fiber Stress at Modulus of Rupture E l as t i c Li mi t Elastfoity

CMPa) CMPa) (1000 MPa)

Position:

Butt 44.0 a1 29.6 a 6.4 a Middle 37.1 b 22.5 b 5.5 a Top 26.7 c 14.5 c 3.5b

Configuration:

Hard-Hard-Hard 43.7 a 26.7 a 6.1 a Hard-Soft-Hard 44.4 a 28.4 a 6."5 a Soft-Hard-Soft 33.0 b 19.6 b 4.8 b Soft-Soft-Soft 22.8 c 13.5 c 3.5 c

Treatments followed by same letter within position or within configuration are not statistically different at the 5% level of significance.

Table 8. DMRT values for the various treatments

TREATMENT

Hard-Hard-Hard: Urea formaldehyde Weldwood Phenol resorcinol Sol id hard wood

Soft·Soft-Soft: Urea formaldehyde Weldwood Phenol resorcinol Solid soft wood

Hard-Soft-Hard: Urea formaldehyde Weldwood

'·Phenol resorcinol

Soft-Hard-Soft: Urea formaldehyde Weldwood Phenol resorcinol

Modulus of Rupture

CMPa)

43.6 Ca> 1 43.7 (a) 43.8 (ab) 44.6 (a)

25.4 Ced) 21.1 (d) 21.9 (d) 26.7 (bed)

42.2 Ca) 48.4 (a) 42.6 (a)

31.4 (be) 33.8 Cb) 33.8 Cb)

PROPERTY Fiber Stress at

E last i c Li mi t CMPa)

26.9 (ab) 21.6 (bed) 31.8 (a) 29.q Cab)

14.0 (de) 14.3 (de) 12.2 (e) 17.4 Cede)

26.6 Cab) 32.8 (a) 27.7 Cabe)

15.8 (de) 21 .2 (bed) 22.0 (bed)

Modulus of E last foi ty (1000 MPa)

5.9 (abC) 6.7 (a) 5 .6 Cabe) 5.8 Cabe)

3.7 (de) 3.2 (e) 3.5 (e) 3.2 Ce)

6.2 Cabe) 6.9 (a) 6.4 Cab)

4.4 Cede) 5.5 (abed) 4.7 Cbcde)

1 Any 2 treatment means followed by any same leter are not significantly different at the 5% probability level.

73

74

undesirable for strong structures since its average MOR was less than the solid soft portion.

Partitioning the treatments into groups using DMR T resulted in: a. groups not mutually exclusive of each other, with H-H-H, H-S-H, solid hardwood and weldwood S-H-S specimens constituting the first group, and b. the last group includ~d two S-H-S specimens (glued with urea formaldehyde and phenol resorcinol) in addition to the S-S-S specimens and the solid soft wood. The results approximated that the MOR difference lay mainly in the order and grouping of the treatments. Generally, specimens with high MOR also had high MOE. The average MOR for the S-S-S group was about half that of the weld wood H-S-H specimen.

The H-S-H specimens performed as well as the H-H-H specimens or the solid hard wood regardless of the glue used. This result is encouraging since it increases the utility of the soft portion of the coconut, which reportedly accounts for about 600/o of the cross-sectional area of a disc (Richolson 1977). Another implication is that for maximum utilization of the whole portion of the tree, an H-S-H configuration can be used instead of an H-H-H conf igura ti on since both do not appreciably differ in strength (MOR). This allows for more uses and greater flexibility as well. Since - large diameter poles dwindling in supply, lamination of small members can be resorted to as shown by the above results.

The soft portion and the specimens in the S-S-S configuration constituted the last group as classified by DMR T. The results were expected due to the relative softness of the material which easily broke on bending. The axerage value for this group (23.7 MPa) was less than half of the value obtained from

H-S-H configuration glued by weldwood (48.4 MPa).

Specimens in the S-H-S configuration had significantly higher strength (31.4 -33.8 MPa) than those in the S-S-S configuration. However, their strength was markedly lower than those in the first group (H-H-H and S-S-H), with values ranging from 42.2 to 48 MPa. This· was expected since the soft portion exhibited lower strength than the hard portion.

The first group of specimens can be used for general framing, conventional furniture and cabinetry, panelling, flooring, door and window frames, stairs and railings, sidings, pallets, joists, scaffolding, shingles and siding boards. The last group is suitable for panellings, roof sarking and purlins, wall frames, claddings, novel ties, sash, household implements, and other ornaments requiring less s'trength (FAQ 1980).

The relationship between strength and stiffness was calculated through the derived reg0e9~Y>n equation MOE = 0.1479 MOR · · , with a cv value of 96.60/o. This implies that MOE can be adequately estimated from the MOR values. This predicting equation does away with the tedious computation of the FSEL required in MOE determination.

On the other hand, FSEL can also be estimated from the MOR values by correlation. The derived regres~~C equation was FSEL = 0.1155 MOR I. , with a cv value of 970/o, indicating that the above equation can account for 97% in the variation of FSEL.

Table 9 shows the comparative strength and stiffness values of solid and gluedlamina ted coco wood against some widely used Philippine tree species for

construction purposes. The values of the butt of both solid hard portions and laminated coco specimens were used since the values for the other species were obtained from the butt.

The solid hard portion compared favorably with mayapis (Shorea palosapis) and tiaong (S. ovata Dyer ex. Brandis) in terms of MOR, but was lower in MOE and higher in FSEL. Against tiaong, it was superior by 2% in MOR and 4% in FSEL, but inferior by 21 % in MOE. It was almost equal to mayapis in MOR and FSEL but inferior by 20% in MOE. Its MOR and MOE values were lower against bagtikan, red lauan, tangile and white lauan.

75

The laminated specimens of the H-H-H and H-S-H configurations had slightly lower MOR, FSEL and MOE values compared with tiaong and mayapis. The H-S-H laminated ·configuration which had the highest strength values among the various configurations, was sligh~ly lower to tiaong in terms of MOR, FSEL, and MOE values (14, 5 and 18% respectively). It was also inferior to mayapis by 17% in MOR, 8% in FSEL and 17% in MOE. It also had lower MOR and MOE values than the Philippine mahogany species and some important Philippine commercial woods like apitong, dao, ipil, lamio, mahogany, molave, narra and palosapis. Despite the relatively. lower MOR and MOE values of laminated coco wood, it

Table 9. Comparison of the strength and stiffness of solid and glue· laminated coconut wood with some Philippine conmercial hardwoods

SPECIES MOISTURE RELATIVE MODULUS STRESS AT MODULUS OF CONDITION DENSITY OF RUPTURE PROPORTIONAL ELASTICITY

% MP a LIMIT MP a 1000 MPa

Coconut (Cocos nucifera Linn.) Solid hard outer portion 15 0.612 62.2 40.8 8.3 Solid soft inner portion 15 0.404 38.1 23.8 4.7

Glued-laminated coconut wood configuration hard·harCl·hard 15 0.578 50.9 35.3 7.6 hard·soft·hard 15 0.588 52.6 36.9 8.6 soft·hard·soft 15 0.546 38.6 25.9 5.1 soft·soft·soft 15 0.412 29.6 18.3 4.2

Philippine mahogany species Bagtikan [Parashorea malaanonan

CBlco.) Merr.] 15 0.495 80.3 51.8 11. 1 Mayapis CShorea R!.losapis CBlco.) Merr.l 15 0.403 63.0 40.0 10.4 Red lauan (Shorea negrosensis Foxw.) 15 0.488 76.8 44.8 11.2 Tangile CShorea polysoerma CBlco.) Merr.] 15 0.470 74.4 43.7 11.1 Tiaong (Shorea agsaboensis Stern.) 15 0.345 61.1 39.0 10.5 White lauan CShorea contorta Vid.) 15 0.435 70.2 43.3 9.4

Other important Philippine Conmercial Woods Apitong (Dipterocarpus grandiflorus Blco.) 15 0.695 99.2 59.5 16.0 Dao CDracontomelon dao CBlco.) Merr.] 15 0.570 93.6 64.0 11. 7 Ipil [lntsia bi juga (Colebr. Ktze.] 15 0.687 101.0 68.2 13.5 Lamio [Dracontomelon edule CBlco.) Skells.] 15 0.470 75.3 48.1 99.7 Mahogany, big·leafed (Swietenia macrophylla

King) 15 0.548 71.6 44.8 8.6 Molave (Vitex parviflora Juss.) 15 0.708 112.0 70.7 13.0 Narra (Pterocarpus indicus Wild.) 15 0.498 91.2 56.0 11.5 Palosapis CAnisoptera thurifera (Blco.)

B ll.ll'lel 15 0.580 80.3 46.4 11.9

76

can still be used for structural purposes provided the size of the members is adequately designed.

CONCLUSIONS

. The strength properties of gluedlaminated coco wood vary in accordance with its position in the tree stem.

. The utility ·of coco wood can be expanded through glued-laminated techniques which will make use of the soft portions of the coco stem.

. The· most suitable combination in coco wood lamina ti on in terms of bending strength is the hard-hardhard and hard-soft-hard configurations.

. The use of urea formaldehyde, phenol resorcinol and weldwood glue does not significantly affect the bending properties. of gluedlaminated specimens. As such, any of the three glues can be used for coco wood lamination for interior purposes.

. MOE can be adequately estimated from the MOR values through the regression equation. This is important since the use of the derived strength relationship will do away with the tedious computation of the FSEL needed in MOE determination.

. On the bases of the MOR and MOE values, the solid hard and the H-HH or H-S-H glued-laminated specimens may be used for general framing, conventional furniture and cabinetry, panelling, flooring, door and window frames, stairs and

ceilings, sidings, pallets, scaffolding, shingles and boards.

joists, siding

The solid soft, the S-H-S and the SS-S glued-laminated specimens may be suitable for light construction such as ceiling, window, jalousies, roof sarking and purlings, wall frames, cloddings, sash, panellings, novelties, household implements and other ornaments requiring less strength.

RECOMMENDATIONS

. Coco stems of other ages should be studied for strength and stiffness to ascertain the effect of age on fiber anatomical characteristics which relate to strength .

. The relationship of relative density with anatomical structure, particularly of vascular bundles, diagnostic cell wall thickness and other features should be conducted at selected sampling intervals from the outer to the inner portion since strength and stiffness vary appreciably between these zones .

The pressing conditions in laminating as used in this study may not necessarily be the optimum for maximum bonding, thereby resulting in lower strength. For a more comprehensive investigation, this point should be looked in to in future studies.

Since the soft portion produces lowstrength wood specimens for optimum utilization, pre-treatment (resin-impregnation or other treatments) is recommended.

77

REFERENCES

AMERICAN SOCIETY FOR TESTING MATERIALS. 1974. Standard procedures for testing small clear specimens of timber: ASTM Designation D143. Annual Book of ASTM Standards. Part 16. Philadelphia, Pa.

FOOD AND AGRICULTURAL ORGANIZATION. improved utilization and marketing of FORPRIDECOM,_College, Laguna. 47-57.

1980. Guidelines for the tropical wood species.

HUNT, G.M 1944. Laminating structural timbers: some words of caution. USDA Forest Products Laboratory Report No. 1449. Madison 5, Wisconsin.

MCLAUGHLAN, J.M 1974. Glue-line shear test on coconut palm timber. Forest Research Institute, Rotorua, New Zealand.

. NISHIHARA, M and M. SUGANO. 1962. Studies on l~minated wood. VII. Gluing conditions of Akamatsu (Pinus densiflora Sieb. et Zucc.) laminated

·wood. Gov't Forest Exptal. Stn. Buli. No. 144. Tokyo, Japan.

RICHOLSON, J.M and R. SWARUP. 1977. A brief review of the anatomy, morphology and physical properties of the mature stem of the coconut palm (Cocos nucifera Linn.). Coconut Stem Utilization Seminar Proceedings. Tonga, New Zealand.

TAMOLANG, F.B. 1980. Search for indigenous raw materials for woodwool board manufacture. ASIAN Forest Industries. Manila: AGRIX Marketing Corpora ti on. 13-18.

TAMOLANG, F.N. 1976. The utilization of coconut trunk and other parts in the Philippines. NSDB Technol. J. 1(2):36-48.

. 1979. The utilization of coconut trunk: on economic --------conservation approach as a business opportunity. Proceedings on World Recycling Congress. Manila, Philippines.

WILSON, T.R.C. 1932. Strength-moisture relations for wood. USDA Forest Products Laboratory Report No. 282. Madison 5, Wisconsin.

. 1939. The glued-faminated wooden arch. USDA Forest Products -------Laboratory. Technical Bull. No. 691. Madison 5, Wisconsin.

and W.S. COTTINGHAM 1947. Test of glued-laminated wooden -------beams and columns and development of principles of design. USDA Forest Products Laboratory Technical Bull. No. R1687. Madi'son 5, Wisconsin.

WALFORD and H.R. ORMAN. 1977. The mechanical properties of coconut timber and its design capabilities in construction. Coconut Stem Utilization Seminar Proceedings. Tonga, New Zealand.

78

BENDING QUALITY IMPROVEMENT OF SOLID BENTWOOD STOCKS FOR FURNITURE COMPONENTS

Robert A. Natividad 1

ABSTRACT

The improvement in the bending property of tangile [ Shorea nolvs perma (Blanco) Merr.] by veneer reinforcement technique was investigated. ' Bentwood samples were prepared by glue-lamination of 3 mm rotary cut veneer at different grain orientation to the face of the solid- stock to be made t:oncave. A total of 50 specimens per treatment were prepared and tested for their critical radii of curvature using the same conditions in the processing of samples and evaluation of bending quality.

A highly significant improvement in bending quality was observed in all treatments subjected to veneer reinforcement. However, the degree of improvement varied significantly depending on the glue-lamination orientation of the veneer reinforcement with respect to the grain direction of the solid bentwood stock.

The best orientation of veneer reinforcement for higher bending property improvement was at _right angle to that of the solid stock. This treatment entailed 149 mm limiting radius of curvature compared to the 323 mm in the control samples at standard level of faultless bends during the bending operation. Parallel grain orientation and cross bonded with the grain of the inner veneer laid perpendicular to the stock resulted in 309 mm and 240. mm critical radii of curvature respectively.

INTRODUCTION

Wood bending is an ancient craft used in making various curved items such as furniture and boat components~ tool handles, agricultural implements, sporting goods and novel ties.

Statistics indicate an increasing demand for bentwood furniture and furniture components in some European countries. Data from the International Trade Center (1982) showed that about US$20.86 million worth of bentwood chairs were imported annually by Netherlands; West Germany, US$19.44 million; France, US$10.42 million; United Kingdom, US$9.42 million, and

Switzerland, US$1.40 million. No information is available on bentwood chair utilization in the United States but the country is reported as the leading producer and user of the product.

In. the .Philippines, wood bending technology is hardly known al though the principle involved is widely practiced in the rattan furniture industry. This may be due to lack of technical knowledge on bentwood fabrication. Local wooden furniture manufacturers produce curved components from massive and straight or laminated stocks by carving with

1 Science Research Specialist II, FPRDI, College, Laguna 4031.

hand tools or by handsa wing to required shape or curvature. This process entails much wastage of raw materials. The resulting product is characterized by impaired strength property because of inclined or crossed grain orientation.

Benchmark information on the bending property of local wood species is also scanty, with only 38 species tested so far. Almost all of these species have "fair" bending quality in solid form and most are rated "good" for laminated bending. Further investigation is needed to improve the bending property of these species especially in solid form. Bending wood in solid form is the simplest and cheapest method of curving items without significantly altering the strength and beauty of wood.

Objectives

1. To develop a technique for making solid· bentworks with relatively sharp curvatures from wood of average bending quality.

2. To improve solid wood bending quality by reinforcing the face of the stock to be made concave with laminated veneer.

3. To determine the effects of different veneer reinforcement bonding orientations on bending quality.

4. To establish the best orientation of veneer re inf orcemen t for improving the bending property of solid wood.

The study was undertaken from January to December 1988 at the Furniture, Wares and Packaging Division (FWPD) laboratory of FPRDI.

79

Li tera tu re. Review

Fa brica ti on of solid curved wooden furniture components and other arched products involves any of these three methods: a. carving by hand tools; b. machining to shape by bandsa w or multiple spindle machine, and c. bending to form (Panshin et al. 1962). The last has obvious limitations but is considered the most economical because it conserves raw materials. Moreover, the end-product is less vulnerable to breakage if the stock is carefully selected and properly processed.

Bentwood stock selection is gov.erned largely by the suitability and availability of wood species used in the manufacture of the desired product. Broad-leafed or hardwood species possess better solid bending qualities than softwoods (Peck 1955 and USDA 1977). Undue breakage during bending may be minimized by avoiding stocks with serious cross -grain, knots, decay, surface checks, shake, pith and brashy wood.

The resilience of wood in its natural state influences its behavior during be~ding operation. Under restricted amount of stress and strain within its modulus of elasticity (MOE) wood can withstand deformation along its length and recover its original shape upon the release of bending stresses (Panshin and de Zeeuw 1970). At the proportional limit, total deformation is non-recoverable as bending stresses impose some permanent set in the wood. However, further bending stresses beyond the proportional limit induce breakage of wood fibers resulting in fracture or total failure.

During bending, the convex side of the stock is stretched or subjected to tensile stresses while the concave side is pushed or affected by compressive stresses. As bending progresses the

80

distortion ca uses the con vex side to be longer than the concave side. Depending on the applied amount of bending stresses, the bent piece must be restrained from springing back and set to the desired moisture content after bending to retain the shape of curvature made (Mendoza 1984). Deformation beyond the proportional limit causes tension and compression failures.

The development of stresses which cause immediate springing back in mild bends or undue failure in sharp curvature during the bending operation is limited in softened or plasticized stocks. Semi-plastic wood compresses considerably and stretches very little (Peck 1955). In sufficiently plasticized stock, the limiting radius of curvature is determined by the maximum permissible extension of wood fibers on the convex face and compressibility of the concave face.

The most suitable softening or plasticizing method for bentwood stock is by steaming or soaking in boiling water (CSIRO 1934, Murphy 1967, USDA 1977). Studies on Philippine woods indicate satisfactory pfasticiza ti on of 25 mm thick stock with 25% MC by steaming at atmospheric pressure and 212°F or soaking in boiling water for 45-60 min (Mendoza 1975, 1984). No improvement in bending property results from prolonged boiling or steaming, and increase in steam pressure.

Stevens and Dean ( 1967) made the first study on wood bending property improvement involving longitudinal compression of the stock . prior to steaming and bending operation. Results showed marked bending propet"ty improvement or smaller radii of · curvatures in pre-compressed specimens compared with those not

subjected to longitudinal compression. A similar test conducted on reef la uan (Shorea negrosensis Foxw.) at FPRDI yielded the same results (Mendoza 1970).

The breakthrough made by Stevens and Dean triggered the development of efficient wood bending equipment. Aside from the spring steel back strap previously used to support fiber stretching during bending, fixed or adjustable and dismountable endpressure devices were incorporated to the bending equipment to induce longitudinal compression. These gadgets increased moldability of plasticized wood to smaller radius of curvature due to proper control of tensile stresses.

Studies on the control of compression failure and the improvement of solid wood bending property are wan ting. This problem is remedied only by resorting to la_minated bending-gluing of thin laminae prior to the bending operation. A straight laminated member can also be. steamed and bent but it requires an adhesive not affected by steaming and does not complicate conditioning of the finished products (USDA 1977).

Based on the theory of laminated wood bending, smaller radius of curvature in solid bending can be achieved by reinforcing with thin veneer the face of the stock to be made concave (Stevens and Turner 1970). The reinforcement assumes the maximum amount of compression which in turn supports and increases the compressive strain on the solid wood base. .


Materials

Tanguile [Shorea polysperma (Blanco) Merr.] served as the raw material. It

,

has a "fair" bending property in solid form and is one of the pref erred species in the manufacture of many wooc:t products not only in the Philippines but also in other countries.

Six log samples with an average diameter of 60 cm and a length of 1.5 m were collected.· Four were processed ,into bentwood stocks and two for veneer reinforcements.

A heat and moisture-resistant adhesive was used in the glue-lamination operation. The glue consisted of liquid c9ld-setting phenol-resorcinol formaldehyde (Cascopen RS 240) mixed with its corresponding catalyst (FM

· 124). These were thoroughly mixed at the recommended proportion with a stirring rod in a beaker.

The amount of glue to apply on the specimens was determined using a weight balance. The glue spread was evenly distributed using a rubberized or manual glue spreader.

Equipment

The lamination was carried out in a 30.5xl52 cm cold press equipped with pressure dial g:iuge and four manually operated ·pressing rams.

Specimens were plasticized in a steam heated retort. Bending tests were done

Figure 1. A manually-operated bending equipment.

81

in a manually operated bending· equipment illustrated in Figure I.

The bending jig had calibrated radii of curvature along the contour or edge of contact point with the specimen. The radii were designed in d~creasing pattern from 500 mm to 75 mm at an increment of 6.25 mm.

Material Preparation

The log samples for bentwood stocks were plainsawn into. 30-mm thick boards at green ctmdition, then kilndried to 18% MC. These were then resawn and planed to required dimensions: 25xl50x1010 mm for control specimens and 22xl50xl020 mm for stocks glued-laminated with veneer.

Logs in green condition were rotary cut for reinforcement into 3-mm thick veneer sheets. The veneer sheets were temporarily clipped to 1100 mm wide sheets, then kiln-dried to 18% MC. The dried veneer were finally clipped to l 50x 1020 mm specimens. Half of the

82

total specimens were cut lengthwise along the grain direction; the other half were cut with the grain at right angle to the 'length of the veneer samples.

The bentwood stocks and veneer reinforcements were sorted, coded and pre-assembled accordingly by treatment. Each assembly unit was glued and pressed at room temperature by batch under the following glue-1,amination conditions:

MC of materials Glue spread Assembly time Pressure Pressing time Curing d ura ti on

18% 293 g/m2 30 min. 10.50 kg/cm2

24 hr 30 da.ys

All bentwood stocks produced per treatment were ripsawed into the final dimension of 25x38x l 020 mm specimens.

Plasticization of Specimens

Samples per treatment were loaded by batch, 10 pieces per batch, at an interval of 10 min in the steaming retort. These were plasticized under the following steaming conditions:

Steam temperature Steaming time Steam pressure

212°F 75 min . 0 kg/cm2

Softened or plasticized batches of specimens were unloaded from the steaming chamber one after the other for the bending test.

Bending Test

While still hot and moist, the specimens were set-up (reinforced side facing the bending jig) and ·bent one by one to the contour of the bending form or jig starting from the largest radius of curvature. Gradual bending was applied and end-pressure was regulated

as the radius of curvature decreased. Each. specimen was bent until it broke. The radius of curvature at which the first failure occurred was recorded per sample.

Experimental Design

The main variables involved in the prepara.tion and testing of specimens in the study were the following:

Treatment

A

B

c D

Veneer Reinforcement Variation

Solid stock, no reinforcement (Control)

Solid stock reinforced with veneer, grain of reinforcement parallel to that of the stock

Solid stock Solid stock reinforced with cross

bonded veneer, grain of outer veneer parallel to that of the stock

Fifty samples per treatment were prepared and tested. Bending quality was determined using the FPRDI Standard Solidwood Bending Property Classification Scheme shown below.

RADIUS OF CURVATURE

(mm) AT WHICH

BREAKAGES DURING

BENDING SHOULD

NOT EXCEED 5% OF

THE TOTAL SAMPLES

150 and below

151 - 250

251 - 500

501 - 750

751 - and up

BENDING

PROPERTY

Very good

Good

Fair

Poor

Very poor

The limiting radii of curvature per treatment at different breakage levels (5, 10, 15 and 20%) were derived using the percentile method of determining proportion or distribution.

"l

Improvement factor in the veneerreinf orc~d specimens was computed by dividing their resulting critical bending radii by those from the control at corresponding breakage percentage level. Factor, more than unity, was considered an indicator of bending property improvement.

The ANOVA from the different treatments were statistically analyzed using the Randomized Complete Block Design (RCBD). The significance of the mean difference between treatments was determined using the Least Significance Difference (LSD) test.


The veneer reinforced specimens in Treatments B, C and D exhibited smaller mean and ctoser range of limiting radii of curvatures relative to the results in Treatment A or control samples (Table 1). Depending on the grain orientation of the veneer reinforcement, the results in Treatments B, C and D also showed discernible degrees of variation from each other.

Compared to the data from the control samples, the highest bending property improvement was attained in Treatment C with a mean critical radius of curvature of 112 mm. This was followed by Treatment D with a mean critical radius of curvature of 144 mm. Treatment B had the least bending property improvement but its mean limiting radius of curvature of 230 mm was relatively smaller than that of the control (255 mm).

Bending Property Analysis

Based on the approximate radii of curvatures at different breakage levels during bending, the effectiveness of

83

veneer reinforcement in improving the bending property of solid bentwood stocks was apparent. This was clearly indicated by the smaller critical radii of curvature obtained in the veneer reinforced samples (Treatments B, C and D) at 5, 10, 15 and 20% breakage levels compared to the solid bentwood stocks or control samples (Table 2).

Furthermore, the improvement factor values derived from the three treatments confirm the above findings. All indices at corresponding breakage levels per treatment exceeded unity factor (1.0) with the control (Table 3). These indicate bending property improvement under treatments with veneer reinforcement.

A highly significant effect of treatment on the critical radii of curvature and improvement factors was obtained (Tables 4 and 5). Comparison of the mean critical radii and improvement factors using the LSD test also indicated highly significant variation between treatments (Tables 6 and 7)~ This means that the degree of variation in the bending properties of the tested bentwood stocks might be due solely to the treatment and that each treatment had entirely different results at both 5% and 1 % probability confidence limits.

The bending property variation in veneer reinforced stocks may be largely attributed to the natural strength of wood under applied forces and orientation of veneer reinforcement with respect to grain direction. During bending, the bentwood stocks were subjected to compression of fibers on the veneer reinforced concave face and tension on the convex face. Since the tensile stresses ·or stretching of fibers on the convex side of the bend were controlled by the metal back strap and end-pressure device, the limit of curvature without fracture during bending depends on the maximum

84

Table 1. Sunnary of bending t~st results by treatment

BREAKAGE RADIUS SD CV NO. OF TREATMENT <nm> (%) SPECIMEN

Mean Min. Max. (pcs.)

A 255 175 325 6.03 2.36 50 B 230 150 300 6.30 2.74 50 c 112 100 150 3.78 3.38 50 D 144 100 225 6~61 4.60 50

Table 2. Critical radii of curvatures at different breakage levels during the bending operation

CRITICAL RADII OF CURVATURES (nm) TREATMENT AT DIFFERENT BREAKAGE LEVELS TOTAL MEAN

5% 10% 15% 20X

A 323 310 305 300 1238 309.50 B 309 296 288 279 1172 293.00 c 149 140 138 136 563 140.75 D 240 231 210 200 881 220.25

Total 1021 977 941 915 3854 240.88

Table .3. Inprovement of factor values in veneer reinforced specimens at different breakage levels based on the results of the control

IMPROVEMENT FACTOR VALUES AT TREATMENT DIFFERENT BREAKAGE LEVELS TOTAL

5% 10%. 15% 20%

B 1.05 1.05 1.06 1.08 4.24 c 2.16 2.21 2.21 2.21 8.79 D 1.35 1.34 1.45 1.50 5.64

Total 4.56 4.60 4.72 4.79 18.67

Table 4. ANOVA results of critical radii of curvature from the different treatments

Total Blocks

SOURCE OF VARIATION

(Breakage level) Treatment Error

OF

15 3

3 9

SUM OF SQUARES

73405.75 1586.75

71507.25 311.75

MEAN SQUARES

528.92

23835.75 34.64

MEAN

1.06 2.20 1.41

1.56

F·VALUE

15.26**

688.10**

85

Table 5. ANOVA results of in.,rov~nt factor values from veneer reinforced specimens at different breaRag~ levels

SOURCE OF VARIATION

Total Block (Breakage level)

Treatment Error

DF

11 3

2 6

SUM OF

SQUARES

2.733 0.010

2.712 0.011

Table 6. Comparison of mean critical radius of curvature between treatments using LSD test

TREATMENT MEAN Cnm>

A 309.50) J } **

B 293.00 ** r· [ -r 140.75 • c

D ** 220.25

permissible fiber compression on the concave side of the bend.

Considering the principles involved in the bending process and the higher compressibility of wood across the grain, Treatment C specimens exhibited higher bending quality improvement compared to the other treatments. The grain of veneer reinforcement in this treatment was laid at right angle to the length of the stocks.

Similarly, Treatment D with cross bonded veneer reinforcement resulted in relatively greater compressibility and consequently better bending quality than Treatment B. Treatment D's grain of innner layer was

MEAN SQUARES

0.0033

1.3560 0.0018

F·VALUE

1.83 ns

753.33**

Table 7. Comparison of mean improvement factor between veneer reinforced specimens using the LSD test

TREATMENT MEAN

B 1.06 J .. ] c ··[ 2.20 **

D 1.41

perpendicularly oriented to the length of the stocks.

In Treatment B, the grain of the bentwood stocks and veneer reinforcement were laid parallel to each other. Thus,' its bending property was inferior to those of Treatments C and D but the degree of improvement was still significantly better than that of Treatment A or solid stocks.

Bending Property Classification

Treatment C had the highest improvement factor and smallest critical radius of curvature at 5% breakage level. · This indicates "very good" bending property (Table 8).

86

Table 8. Bending quality classification by treatment

TREATMENT LIMITING RADIUS OF CURVATURE (11111) AT WHICH BREAKAGE DURING BENDING SHOULD NOT EXCEED 5% OF THE TOTAL SPECIMENS

BENDING PROPERTY CLASSIFICATION

A B c D

Treatments D and B showed "good" and "fair" bending properties respectively.

The critical or limiting radius of curvature at 5% breakage level in treatment A or control samples was classified as "fair". This finding conforms with the bending quality rating for the same wood species studied earlier at the Institute using the same testing method (Mendoza 1984).

Bentwood Characteristics

In this study compression wrinkles were the main failures during the bending operation. Figures 2 to 4 depict the compression failures in treatments A, B and D. The wrinkles

Figures 2-4. Compression failures on the concave side of treatment samples. A (Fig.2), B (Fig. 3) and D (Fig. 4).

323 309 149 240

Fair Fair Very Good Good

on the concave face of the bend typified normal behavior of wood subjected beyond the proportional limit of bending deformation because all samples were bent until the first failure occurred. However, such type of failure was hardly noticeable in Treatment C (Fig. 5). A close look at the bentwood sample intentionally set to around 150 mm radius at its smallest curvature under this treatment is presented in Figure 6.

Figure 5. Specimens tested under Treatment C. The sample at the left was intentionally set to a curvature with a minimum radius of 150 mm at one end.

87

Figure 6. Close-up of the concave side of a bent specimen under Treatment C with a radius of curvature ranging from 500 -150 mm. Note the absence of compression failures or wrinkles.

Thus, Treatment C had the best stocks or control specimens. Based potential for solid bentworks especially on at least 5% estimated breakage on for furniture components which the total number of samples, demand relatively sharper curvatures. specimens under this treatment, Aside from its low susceptibility to steamed and bent with supporting compression wrinkles and spring back back strap and end-pressure device, if properly set, the perpendicularly have a minimum radius of curvature glued veneer reinforcement also of about 149 mm. In contrast, the reduces the tendency of the resulting control samples have a limited bentwood to warp and split. bending radius of about 323 mm

under normal condition.

CONCLUSIONS

The bending quality of solid bentwood stock may be improved by reinforcing the surface to be made concave with glue-laminated veneer before the plasticizing and bending operations. However, the degree of improvement varies with the grain directiOn of the reinforcement along the length of the bentwood stock.

The best grain orientation of the veneer reinforcement for better bending property improvement is perpendicular to · that of the bentwood stock. This treatment results in the highest bending property improvement factor gauging from the minimum radius of curvature of the unreinforced

RECOMMENDATIONS

. The above technique may be employed with minimal additional processing cost in fabricating tangile bentwood furniture components that require about 150 mm minimum radius of curvature.

It may also be adopted to improve the bending performance of other wood species but the degree of improvement will depend on the bending characteristics of the species under normal conditions.

. Should the veneer reinforcement affect the physical appearance of the final product or a single-piece

__J

88

member is desired in the end, this can be removed (after the bend shall have been properly set) with the use of router during the machining operation. Henceforth, if the reinforcement is intended to be removed, the materials may not necessarily be processed from the same species provided no complication ensues in the glue lamina ti on process and in the resulting bond durability. For best

results, reinforcement from species of very good bending quality must be used.

. Lastly, only· heat- and moistureresistant adhesives should be used in the glue-lamination of the reinforced bentwood stocks because of the steaming or boiling treatment that has to be done before the bending operation.

LITERATURE CITED

CSIR. 1934. Timber bending. Council of Science and Industries Re~earch, Division of Forest Products, Australia. Trade Circular 22.

ITC. 1982." Major import markets for wooden household furniture. Geneva, International Trade Center UNCTAD/GATT.

MENDOZA, E.U. 1970. The effect of longitudinal compression on the bending properties of red lauan (Shorea negrosensis). Phil. Lumberman 16(9):34-37.

1975. A compilation of articles on wood bending. FPRDI Library, College, Laguna.

1984. Bending properties of Philippine woods. FPRDI J. 13(2):54-67.

MURPHY, W.K. 1967. Pretreatment of bending stock. For. Prod. J. 16(9):75-76.

PAN SHIN, A.J. et al. 1962. Forest products. 2nd ed., New York, McGraw Hill Book Co.

PANSHIN, A.J. and C. DE ZEEUW. 1978. Textbook of wood technology. Vol. 1. 3rd ed. New York, McGraw Hill Inc.

PECK, E. 1955. Bending solid wood to form. USDA Forest Service, Madison, Wisconsin, FPL 1764.

STEVENS, W.C. and A.R. DEAN. 1967. Method for improving bending properties of wood. For. Prod. J. 17(5):49-50.

------ and N. TURNER. 1970. Wood bending handbook. HMSO, London, Eng.land.

USDA FOREST SERVICE. 1977. The encyclopedia of wood. New York, Drake Publishers, Inc.

89

EFFECTS OF MOISTURE CONTENT AND MONOM:~R MIXTURES ON THE POLYMERIZATION OF KAATOAN BANGKAL [Anth.ocephalus chinensis (Lam.)

Rich. ex Walp.], MALAKAUA YAN (Podocarpus rumphii Blume) AND WHITE LAUAN (Shorea contorta Vid.) FOR TOOL HANDLES

Josephine P. Carandang1

ABSTRACT

The effects of moisture content on the reaction of monomer mixtures with three Philippine wood species were studied. Kaatoan bangkal, malakauayan and white lauan dried at two moisture content levels were treated with two varying mixtures of unsaturated polyester and styrene using the heat-catalyst method. Benzoyl peroxide at 0.5% by weight was used as the catalyst. A bench-scale impregnating apparatus served as the treating chamber. The full-cell process was employed following the ASTM D 1413-61 treatment method. Hardness test was conducted following the ASTM standard .. Unimpregnated and impregnated specimens were observed under the scanning electron microscope ( SEM).

Interpretation and. discussion of the data were based on improvement in specific gravity, chemical- and polymer loadings and hardness. In Kaatoan bangkal, the impregnant was selective in terms of the cellular elements that were penetrated. SEM micrographs of impregnated kaatoan bangkal showed that its vessel elements were filled with the impregnant, while the fibrous elements were not.

INTRODUCTION

The wood-using industries are faced with a decreasing supply of traditional wood species for specific uses. Textile implements, tool handles and other woodwares require harder and more shock-resistant materials. The introduction of plastic as tool handles seems to be unpopular because of some inherent disadvantages of the material for the purpose. Wood remains the best material for handles in various types of tools.

Several studies have tried combining wood with certain kinds of plastic to improve the f ormer's dimensional stability and mechanical properties.

One such product is the wood-plastic composites (WPC), popularly known as wood acrylics. Current applications of wood acrylics in the United States are listed in Table 1. New areas of application include lamella flooring, specialty items, large handles and special environment items. Impregnation of wood with vinyl monomers and methods of curing are either by gamma-radiation or heatcatalyst method. Radiation curing requires high volume production and higher initial investment. The latter is considered more practical and economical for small and occasional runs.

1 Science Research Specialist II, FPRDI, College, Laguna 4031.

90

Table 1. Application of acrylic wood

PRODUCTION METHOD IRRADIATION HEAT CATALYST

Flooring Stair Treads Handrails and Moulding Handles and Knobs Bows and Gunstocks Martial Arts Devices Golf Clubs Desk Items Bag Pipes Veneer/Lamella Surface

x x x x x x

x

x

x

x

x x x x

Reference: A.E. Witt, P.O. Henise and L.W. Griest. 1980. Acrylic Woods io'the United States. Third International Meetil19 on Radiation Processing, 26-31 October 1980, Tokyo, Japan.

Methylmethacrylate (MMA) is the most common monomer used in the production of WPC because of its desirable properties. However, it is rather expensive. Other cheaper and locally available vinyl monomers or monomer mixtures may be used to produce composites of widely modified properties.

Some properties to consider in selecting wood for tool handles are hardness, toughness, grain direction, drying characteristics and working qualities. However, not all wood species have these characteristics. Thus, this study was undertaken to evaluate the properties of WPC and the utilization of easily available but less durable species.

Obj~ctives:

I. To determine the effect of moisture content and monomer mixtures on

specific gravity improvement, chemical and polymer loading and hardness in treating kaatoan ba·ngkal, white lauan and malakauayan.

2. To evaluate the aforementioned properties and the performance of treated materials.


Wood-plastic composites started in the U.S. with the introduction of gammaradiation curing in 1961 by Kent et al. (1963) and heat-catalyst curing in 1965 by Meyer. Researches on WPC production using either method were intensified in Europe in the late 60s (Iya 1968, Miettinen 1968, Autio and Miettenen 1970) and in some Asian countries like Japan (Hirayama 1968, Tanijuchi and Furuya 1976, Kawakami et al. 1982), India, , Thailand and Pakistan.

A study on 12 Philippine wood species for WPC was conducted by Miettinen (1966) at the University of Helsinki, Finland. Wood samples were treated with polystyrene at a 1:1 ratio, polymerized by gamma-radiation, and tested for compression and hardness. Results indicated that santol [Sandoricum koetjape (Burn. f .) Merr.) had the highest polymer retention -of about 40% and good improvement in strength values. It was followed by lomarau (Swintonia foxworthyi Elm.), malakauayan (Podocarpus rumphii Blume), bok-bok [Xanthophyllum excelum (Blume) Miq.], talisai-gubat (Terminalia foetidissima Griff.) and lanutan-bagyo [Gonystylus macrophyllus (Miq.) Airy Shaw). No sufficient impregnation and improvement in properties were observed in yakal-gisok (Shorea gisok Foxw.), Katong-lakihan (Amoora macrocarpa Merr.), , palosapis [Anisoptera thurifera {Blanco) Blume], akle [Serialbizia acle (Blanco)

Kos term.], mangachapui (Ho pea acuminata Merr) and molave (Vitex parviflora Juss.)

Limited studies were conducted in the Philippines by Bonoan (1968) on kaatoan bangkal impregnated with MMA and polymerized by irradiation. The Forest Products Research and Development Institute applied the heatcatalyst curing process on bagtikan, dita, kaatoan bangkal, white lauan and yakal (Generalla and Casin 1973, 1978, Generalla 1976). Wood samples were treated with MMA monomer and benzoyl peroxide (BPO) catalyst and heat-cured in an oven for 24 hr at 10°c. Preliminary work resulted in composites with increased hardness and toughness and greater dimensional stability than the untreated wood, exce·pt for yakal which proved difficult to impregnate. Dita showed the highest improvement in hardness and toughness at 70% and 46% respectively, followed by kaatoan bangkal and bagtikan. Likewise, Casin and Serizawa (I 980) conducted experiments on gubas and white lauan using the heat-catalyst method.

Chemical modification of wood cellwall polymers is effective in reducing the tendency of wood to change dimensions when in contact with moisture (Rowell and Gutzmer 197 5, Rowell et aL 1976, Rowell and Ellis 1978, 1979). It is also a promising approach in reducing biological attack by microoi;ganisms (Rowell and Gutzmer 1975, Rowell 1980, Rowell and Ellis 1981 );, termites (Rowell et al. 1979) and marine organisms (Johnson and Gutzmer 1981).

A problem encountered in wood acrylics production is the final finish and milling of the product (Witt 1980). However, with conventional finishing equipment, it is possible to approach the glass transition tempera tu re of the

91

polymer with a resultant short life for sanding materials. Addition of crosslinking agent substantially improves the finishing properties of wood acrylics (Meyer 1977).


Wood Specimen Preparation

The heartwood portions of white lauan (Shorea contorta Yid.), kaatoan bangkal [ Anthoce phalus chinensis] and malakauayan (Podocarpus rumphii) were cut into 5x5x15 cm specimens and dried at I 0 and 15% MC levels. These represented the approximate moisture contents of kiln-dried and air-dried stocks respectively.

Moisture content, specific gravity and original weight were determined individually for each specimen. From the average moisture content, the calculated oven-dry weight was determined and used for computing the weight at different moisture content levels (W 1 ). The specimens were endcoated with epoxy resin (Pioneer regular formula) and cured overnight inside a dessicator at room tempera tu re (W2).

Preparation of the Impregnating Chemicals

Polylite 31-006 (USP) and styrene purchased from Polymers Inc., Metro Manila were used as the raw materials for the impregnation. Benzoyl peroxide used as catalyst was obtained from the stock of the Housing and Utilities Program of FPRDI. Pertinent characteristics of each material are summarized in Table 2.

The impregnating solution was prepared by dissolving the calculated weight of BPO in the specified percentage of total weight of the

Table 2. Characteristics of the components of the fq>regnant

COMPONENT FORM

Polylite 31·006 (USP)a Liquid

Styrene (Sty)b Liquid

Benzoyl peroxige Coarse wh;te catal,yst (BPO) crystals

PROPERTIES

Viscosity at 25°C·2700 to 3700 cps Specific gravity at 25°C·1.155 to 1.165 Weight/gal., lbs. (approx.) • 9.68 Health & safety factors·flanmable

Fornula weight • 704.14 ·Purity, wt. X, Win · 99.3 Viscosity at 25 C ·0.080 cp Health and safety factors · toxic and flanmble

fOMILlla wef ght · · · 242.22 Purity, wtX • 99.8 Stable at ordinary t~rature Health and safety factors • flannable

References: ~esins Inc. Technical Bulletin Encyclopedia of Chemical Technology, Vols. 2 and 13

mixture to the styrene monomer. As soon as the BPO was dissolved, the mixture was added to the USP. Two mixtures of USP and styrene at ratios by weight of. l:l and 2:1 were used. For the two mixtures, 0.5% by weight of BPO was added.

Selection of these chemicals was based on their availability in the Philippine market, economic cost and safety in use.

Impregnation Process

Two wood specimens for each run were placed In a stainless steel beaker in the treating chamber of a bench-scale impregnating apparatus. Glass rods were inserted between the spaces to prevent the specimens from floating during impregnation.

The full-cell process was employed with the following schedule patterned after the ASTM Dl413-61 treatment method: 1. initial vacuum at 76 cm Hg for 30 min; 2. introduction of impregnating solution into the system without breaking the va~uum, and 3. application of 10 kg/cm pressure to the system by using compressed

nitrogen gas and maintaining the pressure for 1 hr at room temperature. Nitrogen was us.ed instead of oxygen because ·oxygen inhibited polymerization.

After impregnation, the specimens were removed from the treating chamber, wiped dry with a cotton cloth to remove surface impregnating solution, ~nd immediately weighed to the nearest 0.01 g (W3). These were then wrapped in aluminum foil· to prevent monomer evaporation from the surface and ensure 'Yniform plastic distribution through the sample. A curing period of 24 hr at 10°c was observed for all experiments. After polymerization, the aluminum wrappings were removed. The specimens were weighed (W 4) and redried in the oven at the same polymerization temperature of 10°c for another 24 hr.

Computations

Chemical and polymer loadings were calculated as follows:

W3 -W2 Chemical loading%= x 100

W1

Polymer loading % • x · 100

where: =weight of wood -= weight of wood after

sealing the cut ends with epoxy resin

=weight of wood after impregnation

=weight of wood after polymerization

Hardness Test

Radial and tangential sections of the untreated (control) and impregnated (treated) specimens were tested for hardhess using the Tinius Olsen Universal Testing machine. The ASTM D143-52 was followed.

Toughness test was not conducted because of inadequate sample measurement required for the test.

Section Preparation and Observation

Microtome sections of 20 um were cut from the middle of the transverse sections of the control and treated· specimens. Scanning electron microscope observation was done at the Microbiology Laboratory of the Institute of Biological Sciences, University of the Philippines at Los Banos (UPLB).


Results of this study are discussed by species. Selection of the three species was based on the FAQ (1980) classification as follows: moderately low and low specific gravity; easy to treat and plantation and commercial species. Anatomical description of the species· are provided by Meniado et al. (1974).

93

White Lauan

ANOV A results showed a highly significant effect of moisture content on the improvement of specific gra-vity and a significant effect on polymer loading in impregnated white lauan specimens (Table 3). Specific gravity consistently improved at the 10% MC level and to a lesser extent at the 15% MC level. The average polymer loading of 22.3% at the 10% MC level was very much higher than the 12.9% exhibited at 15% MC. A higher moisture content in wood during chemical modification causes the chemicals to react with the hydroxyl group in water, thereby creating greater resistance to the flow or penetration of chemicals (Rowell and Ellis 1984).

On the other hand, chemical ratio and the interaction between chemical ratio and moisture content had no significant effects on specific gravity improvement, chemical and polymer loading after impregnation. The impregnated specimens exhibited only surface retention of the impregnant which may be attributed to the tyloses present in white lauan. When the vessels or pores of a hard wood are filled with tyloses or gums, movement of liquids through them is obstructed (MacLcan 1952). The low retention in white lauan has been observed in previous studies using other iinpregnan ts ( Generalla and Casin 1973). SEM micrographs of control and impregnated white lauan specimens arc shown in Figures l and 2.

Chemical ratio, moisture content and their interaction had .highly significant effects on radial hardness (Table 4). Only moisture content and the interaction between chemical ratio and moisture content had highly significant effects on tangential hardness.

Table 3. Sunnary of ANOVA 1-~~ults on specific gravity iq:>rovement, chemical and polymer loadings in white lauan, kaatoan bangkal and malakauayan specimens.

SPECIFIC GRAVITY IMPROVEMENT CHEMICAL LOADING SOURCE OF VARIATION WL KB MLK WL KB

A 2.20ns

B

A · Chemical rati~ B · Moisture content ns · not significant *

23.13

** · significant at 5X level · significant at 1X level

**

** 46.47

** 16.28

** 21.08

3·.31ns 0.02ns ** 72.55

·o.66ns 4·51ns ** 63.38

2.08ns o.o5ns ** 23.97

WL · White lauan _KB · Kaatoan bangkal

MLK · Malakauayan

POLYMER LOADING MLK WL KB MLK

4.36ns 0.28ns ** * 62.24 5.54

** * ** ** 28.09 8.34 65.76 27.66

0.24ns 0.01ns 16.28 0.88ns

95

Table 4. ANOVA results on radial and tangential hardness in white lauan, kaatoan bangkal and malakauayan specimens

H A R D N E S S T E S T

Radial Tangential SOURCE OF WL ICB MLIC WL KB MLK VARIATION

** ns * ns * 2.0-r,: A 24.98 •• 1.31ns 5.60,, 4.46i,. 9.20ns B 160.45** 0.06** 7.67 * 40.ot,. ~.43* 4.68~

Ax B. 74.08 9.64 4.88 16.0 7.09 3.9

A · Chemical ratio B ~ Moisture content ns · not significant

WL · White lauan KB · ICaatoan bangkal

MLIC · Malakauayan * · signrficant at 5% level ** · significant at 1% level

Kaatoan bangkal

The effects of moisture content, chemical reaction and their interaction on the improvement of specific gravity, chemical and polymer loadings were highly significant on kaatoan bangkal after impregnation (Table 3). Kaatoan bangkal showed higher improvement in specific gravity, chemical and polymer loadings than white lauan. The penetrability or flow of chemicals/ liquids in easy-to-treat hardwood species depends primarily on the type, size and number of pores per unit area. Kaa toan bangkal has bigger pore sizC( with predominantly radial multiples up to 4 or more cells (Meniado et al. 1981) than white lauan. Figures 3 and 4 show the SEM micrographs of kaatoan bangkal before and after impregnation. The vessel elements appeared receptive to the impregnant.

The hardness test (Table 4) revealed that only the interaction between chemical ratio and moisture content had highly significant effect on the radial section of impregnated kaa toan bangkal. In contrast, chemical ratio and the interaction between chemical ratio and moisture content affected the tangential section.

Malakauayan

Chemical ratio, moisture content an.d their interaction had no significant effects on the improvement of specific gravity (Table 3). Chemical ratio and the interaction between moisture content and chemical ratio, likewise, had no significant effects on chemical loading. Meanwhile only the interaction between chemical ratio and moisture content had no significant effect on polymer loading. This implies that chemical and polymer loadings at the low MC levels differed from each other. The average chemical loading significantly increased Crom the 15% to the 10% MC level. Likewise, the average polymer loading increased in the same order of moisture content levels. The interaction between moisture content and chemical ratio had no significant influence on chemical and polymer loadings.

On hardness test, chemical ratio, moisture content and the interaction between both variables significantly influenced the radial section of impregnated malakauayan specimens (Table 4). However, no significant effect of any of the three variables was observed on the tangential section.

96

Fl1ures 1-6. SEM micrographs of control specimens or white lauan (1, 60x), kaatoan bangkal (2, 80x) and malakauayan (3, 80x); impregnated specimens of white lauan (4, 60x), kaatoan bangkal (5, 80x) and malakauayan (6, 80x).

This implies that hardness values in the radial section · differed from each other, but not in the tangential section.

SEM micrographs of control and impregnated malakaluayan specimens are shown in Figures 5 and 6 respectively.

The results can be compared with previous reports on similar species impregnated with MMA-based systems. While there are significant differences in the chemical properties of. USP. and MMA, there seems to be a common ground between wood specimens impregnated with these two mixtures. The results for white lauan and kaatoan bangkal qualitatively agree with the findings of Generalla and Casin (1973) for the same species impregnated with MMA. The nature of the polymer had little effect on the properties of the WPC compared with the effect of the wood species. Only the cheapest, easily polymerizable monomer mixture can, therefore, be considered for economic reasons.

CONCLUSIONS

A lower moisture content significantly improves white lauan's specific gravity after impregnation. In contrast, USP-styrene mixture and its interaction with moisture content do not significantly affect white lauan during impregnation.

Tyloses or gums greatly affect the movement of impregnants in white la uan as shown in the SEM microgiaphs.

A lower moisture content greatly improves kaatoan bangkal's specific gravity, chemical and polymer loadings after impregnation. The values are much higher than those for white lauan.

97

A lower moisture content significantly improves malakauayan's specific gravity after impregnation. On the other hand, the USP-styrene mixture, moisture content and their interaction do not improve the specific gravity of malakauayan, although it has a higher chemical loading after impregnation. After polymerization, the lower moisture content has higher polymer loading than the higher moisture content.

A lower moisture content gre~tly improves the specific gravity of the three species in decreasing order: KB> WL > MLK.

. The two moisture content levels improve chemical loading in kaa toan bangkal, but not in white lauan. In malakauayan, it is only the lower moisture content level which improves chemical loading.

After polymerization, polymer loading greatly improves in the three species in a decreasing order: KB> MLK > WL.

. DMRT results indicate that the hardness of impregnated sp~cimens vary with moisture content levels and chemical ratio. The variation is due to their anatomical and anisotropic characteristics (Tamolang et al. 1960, Meniado et al. 1974, Vela 197 4, Meniado et al. 1981).

RECOMMENDATIONS

. Further studies on other commercially available, plantationgrown or lesser-known species should be conducted.

. Some treatment variables such as

98

pnsaare, polymerization temperatures aad curing time should be varied.

Locally available USP may

substitute for 'MMA.

The use of impregnated kaatoan bangkal in the manufacture of tool handles should be validated.

REFERENCES

AMERICAN SOCIETY FOR TESTING AND MATERIALS: D-1413-61 Reapproved. 1970. Standard method of testing wood preservations by laboratory soilblock cultures. 1970 Annual Book of ASTM Standards. Part 16:1013-1023.

----------~~~~-----:-------~----------------~--------~~------------------------~· 1980. Methods oC testing small clear specimens of timber. ASTM Designation D 143-52.

AUTIO, T and J. K. MIETTINEN. 1970. Experiments in Finland on properties of wood•polymer combination. For. Prod. J. 20 (3): 36-42.

BONOAN, L. S. 1968. A contributed report on " Status snd Technology of Polymer-Containing Fibrous Materals in the Eastern Hemisphere". In Impregnated Fibrous Materials. IAEA, Vienna, Austria. 250-261.

CASIN, R..F. ud N. C. GENER.ALLA. 1978. Modification of the physical and mechanical properties of bagtikan and dita with vinyl monomers. FOR'.PRIDE Digest 8 (1):35-43 .

aad M. SER.IZAWA. 1980. Polymerization temperatures in gubas and -----W·hite lauan impregnated with styrene and unsaturated polyester resin. FPRDI, College, Laguna. Unpubl.

FOOD AND AGRICULTURAL ORGANIZATION OF THE UNITED NATIONS (FAQ). 1980. Guidelines for the impro'ved utilization and marketing of tropical wood species.

GENERALLA, N. C. and R. F. CASIN. 1973. Wood-plastic combination. First Progress Report. FPRDI Library. Unpubl.

. 1976. Modification of the physical and --------------------------------------------------------~ mechanical properties of bagtikan, dita and yakal with vinyl monomers.

Second Progress Report. FPRDI Library. Unpubl.

HIRAYAMA, T. 1968. A contributed report on "Status and Technology of Polymer-Containing Fibrous Materials. In Impregnated Fibrous Materials. IAEA, Vienna, Austria. 250-261.

IYA, V.K. 1968. A contributed report on "Status and Technology of Polymercontaining Fibrous Materials in the Eastern Hemisphere". In Impregnated Fibrous Materials. IAEA, Vienna, Austria. 231-249,

99

JOHNSON, B.R. and D.I. GUTZMER. 1981. Marine exposure of preservativetreated small wood panels. U.S. Department of Agriculture, For. Serv. Res. Pap. FPL 399. For. Prod. Lab., Madison, WI. 14

KENT, J.A. WINSTON and W. BOYLE. 1963. Preparation of wood-plastic combination using gamma radiation to induce polymerization: effects of gamma radiation on wood US AEC. Report ORD-600.

KAWAKAMI, H.K. TANEDA, S. ISHIDA and H. OHTAMI. 1982. Observation of polymer in wood polymer composite. Abstract Bulletin of the Institute of Paper Chemistry, 52(7) ..

MACLEAN, J.D. 1952. Preservative treatment of wood by pressure methods. Agriculture Handbook No. 40. USDA.

MEYER, J.A. 1965. Treatment of wood-polymer system using catalyst-heat techniques. For. Prod. J. 15(9):362-364.

1977. Wood-polymer composites and their industrial applications. ACS Symposium Series, No. 43:301-325.

MIETTINEN, J.K. 1968. A contributed report on "Status and Technology of Polymer-containing Fibrous Materials in the Eastern Hemisphere". In Impregnated Fibrous Materials. IAEA, Vienna, Austria. 152-16'8.

ROWELL, R.M 1980. Distribution of reacted chemicals in southern pine modified with methyl isocyanate. Wood Sci. 13(2):104-110.

and W.D. ELLIS. 1978. Determination of dimen,sional stabilization ------of wood using the water-soak method. Wood Fiber .10(2):104-lll.

. 1979. Chemical modification of wood:reaction of --------~---~ methyl isocyanate with southern pine. Wood Sci. 12(1): 52-58.

1981. Bonding of isocyanates to wood. P. 263-284. In Urethane chemistry and applications. K.N. Eduards (ed.). Am. Chem. Soc. Symposium Series 172, Chap. 19.

1984. Effects of moisture on the chemical modification of wood with epoxides and isocyanates. Wood and Fiber Sci., 16(2):257-267.

and D.I. GLUTZNER. 1975. Chemical modification of wood:reactions of alkylene oxides with southern yellow pine. Wood Sci. 9( I ):51-54.

WITT, A.E. 1980. Acrylic; woods in the United States. Third International Meeting on Radiation Processing. 26-31 October 1980. Tokyo, Japan.

100

FPRDI PUBLICATIONS FOR SALE

1. Lexicon of Philippine Trees by F. M Salvosa

2. Standards & Procedures for Descriptions of Dicotyledonous Woods by F.N. Tamolang et al.

3. Wood Identification Handbook Vol. I by J .A. Meniado et al.

4. Wood Identification Handbook Vol. II by J.A. Meniado et al.

5. Timbers of the Philippines Vol. I by J.A. Meniado et al.

6. Philippine Timber Series

a. Nos. 1 to 7 - Red lauan, Tangile; Tiaong~ Almon, Bagtikan, Mayapis and White lauan

b. Nos. 8 to 14 - Agoho, Almaciga, Apitong, Binggas, Lanipau, Narra and Palosapis ·

c. Kaa toan bangkal d. Vidal lanutan e. Binuang f. Moluccan sau

7. FPRDI Mature Technologies

a. Volume 1 (various technologies on housing and materials; paper, chemical products and dendro-enegry and furniture, wares and packaging)

b. Volume 2 (coconut utilization technologies)

8. Forest Products Technoflow

a. Series 1 - Pandan cocooning frames: dollar saving technology b. Series 2 - FPRDI sawdust carbonizer and manual briquettor c. Series 3 - FPRDI furnace-type manual dry kiln d. Series 4 .. High pressure sap displacement treatment e. Series 5 - Metal plate fastener .for coconut lumber truss

construction f. Series 6 - Chemical treatment and seasoning of rattan canes g. Series 7 - Handmade paper from rice straw h. Series 8 - DOST kiln dryer for curing onions i. Series 9 - Woodwool Cement Board: A low cost panel from

indigenous material j. Series 10 - Solid wood bending technology

9 FPRDI Jour.nal

FPRDI JOURNAL

A PUBLICATION FOR FOREST PRODUCTS RESEARCH . AND DEVELOPMENT INDUSTRIES

EDITORIAL STAFF

Editor Assistant Editor Editorial Secretaries

Artist/ Illustrator

TECHNICAL REVIEW COMMITTEE

Center Chief Most Concerned Chief Statistician

EDITORIAL BOARD

Chairman Vice~Chairman

Members

TECHNICAL ADVISERS

Dr. Emmanuel D. Bello . Acting· Director

Emerita R. Barile Rizalina K. Ararat Felisa M Talatala Aquina D. Mendoza Froilan B. Samiano

Dr. Justo P. ·Rojo Yolanda U. Robillos Arsenio B. Ella Robert A. Natividad Sylvia Katherine S. Lopez Emerita R. Barile Rizalina K. Ararat

Dr. Joaquin 0. Siopongco Deputy Director

Produced by the Technical Information Staff, TUD December 1989

FPRDI JOURNAL

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•For book E.g. READ, H. 1972. Communication: methods for all

media. University of Illinois Press. Urbana, Chicago, London.

• For section of a book Same as book citations except that the section is placed before the book title. Use In (underlined and first letter capitalized) to indicate that the article or chapter is taken from a book. E.g. ESCOLANO, J.O. and P.V. BAWAGAN. 1988. Pulp, paper, fiberboard and chemical products. In

Coconut wood utilization research and development: the Philippine experience. J.P. ROJO, F.O. TESORO, S.K.S. LOPEZ and M.E. DY (eds.). Forest Products Research and Development Institute and International Development Research Center (Canada). College, Laguna, Philippines. pp. 87-99.

•For unpublished work Same as other citations but indicate the type of document used. E.g. PABLO, A.A. and J.B. SEGUERRA JR. 1974. Development·of particleboard on a pilot plant

and semi-commercial scale using plantation and secondary wood species and agricultural fibrous waste materials. II. Kaatoan bangkal and Moluccan sau. Unpublished progress report. FPRDI, College, Laguna.

•For newspaper/magazine E.g. ANONYMOUS. 1956. Crystallography. Encyclopedia Brittanica, Chicago. 6:808-829.

All articles will be referred for relevance and quality to outside referees and/ or in-house staff who are experts or knowledgeable on the subject mQtter discussed.

ABOUT THE COVER

The pictorial shows the process of bending solid wood as material component of furniture such as chairs and ta bl es. The process is fully discussed in the article ori page 78.

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