Volume 19 Nos. 1-4

FPR.DI "OURnAL

ISSN 0115-0456 January-December 1990

FPRDI "OURn•L

A PUBLICATION FOR FOREST PRODUCTS RESEARCH AND DEVELOPMENT INDUSTRIES

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STI-04-7524

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FPR·DI JOURNAL

Volume 19 Nos. 1 .. 4 Janvary-Decem.ber 1990 .

Entered as Second Class Matter on 21 December 1984 at the College Post Office, L~guna 4031 ~ Philippines

The FPRDJ Journal projects the research and industries development efforts of the Forest Products Research and Development Institute

. <FJ>iou.

TABLE OF CONTENTS

EvaJuation of ipil-ipil seed gum as a strengthening cbei;nical for paper e> B~eaa S. Pamploaa, Yo1anda L. Tavita

Atlene A. Siha and Norberto G. Ambagan

Field service testing of grocery product pallets from cocenut (Cocos nucifera L.) lumber o L~lita V. Villa velez

The taxonomy and wood anatomy of three Philippine Anisopter4 (Palosapis group) s~cies (Dipterocarpaceae) o Arseaio B. Ella, Ramiro P. Esco bin and Mario M. Maruzzo

Properties of green and yellow varieties of coconut (Cocos n{lelf era L.) e> Zeoita B. Espiloy, Marina A. Alipoa, .·Mario K Matuzzo and Mariluz SP. Dionglay

Physical and mechanical properties of bagras (Eucalyptus deglupta Blume) from Paper Industries Corporation of the Philippines e Marina A. Alipoa ·aad Apol.onio R. Floresca

The critical load of timber column of varied slenderness ratio o ~ariqae B. Espiloy, Jr.

Laminated veneer lumber (L VL) from industrial tree plantati~n species: Yemane (Gmelinil arborea R. Br~) o JJH~Jlo~C .. l>9lo·r.;s; Emmanue.I Noli B.,Sica4 and

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18

EVALUATION OF IPIL-IPIL SEED GUM AS A STRENGTHENING CHEMICAL FOR PAPER

Buena S. Pamplona, Yolanda L. Tavita, Arlene A. Silva and Norberto G. Ambagan 1

ABSTRACT

A simple process was developed to produce a dry-strengthening gum additive to paper from locally grown giant ipil-ipil [Leucaena Ieucocephala (Lam.) de Wit] seeds. The process involved grinding and cooking the ground seeds in water at 70°C to so0 c.

The gum was analyzed for its composition, viscosity and pH, then tested for effectiveness as a dry-strengthening agent for pulp hand sheets made from commercial pulps, namely: sugarcane bagasse, lauan unbleached kraft, unbleached kraft pine (UKP), kraft cuttings (KC) and a mixture of 30% UKP and 70% KC.

The strengthening ef feet of the ipil-ipil gum was comparable with that of commercial guar gum at low addition levels of 0.2% to 0.6% to each pulp sample used. Likewise, tests on handslieets showed that the gum could be used in either acid or neutral stock.

The ipU-ipil gum was used as a substitute for guar gum to produce 52.8 tons of Class A and B extensible sack paper at the United Pulp and Paper Corporation plant. The white-water had low level of residual suspended solids.

INTRODUCTION

High quality but relatively cheap paper additives can be locally produced from abundant .and renewable plant sources using simple and inexpensive manufacturing processes.

Hcteropolysaccharide gums from legume plants such as guar (Astragalus tetragonolobus) gum, locust bean (Ceratonia siliqua) gum, gum arabic (Acacia senegal) and gum tragacanth (Astragalus sp.) in natural and modified forms are commercially used as paper

adhe.sives. Locally, the single deterrent to full utilization of these gums for paper is the high importation cost.

FPRDI researchers have discovered that local giant ipil-ipil seeds arc good raw material sources for making paper adhesive. This is principally due to the presence of considerable amount of galactomannan (GM), the same active gum component present in guar and locust bean gums.

1 Researchers, Paper, Chemical Products and Dendro Energy Division and Furniture, Wares and Packaging Division, FPRDI, DOST, College, Laguna 4031.

2

Objective

To investigate the potential of the ipil­ipil seed gum as a beater additive to paper.

Review of Literature

Most legume seed GM molecules (M. wt., 150,000 - 650,000 units) consist of a mannose main chain and varying amounts and sequences of single galactose branching (Asp,inall 1983). A beta-(1,4)-glycosidic bond connects any two beta-D-mannose units in the chain. An alpha-(1,6)-glycosidic linkage joins alpha-D-galactosc and beta-D-mannose units (McCleary 1975, 1979).

McCleary reported that L. leucocephala galactomannan does not contain long sections of contiguous unsubstituted mannose residues. Rather, a large section of the molecule consists of

Gal I

many (n) repeating units (-Man-Man-)n and that all the galactosyl groups in these are located on one side of the mannan chain. This structure is supported by the enhanced interaction of L. leucocephala gum when acted upon by zanthan gum.

The molecules possess the properties of both linear and branched molecules with exposed secondary and primary hydroxyl groups.

Russo as cited by Swanson (1956) proposed two processes to show how the gums interact with cellulose fibers. First is the deposition of the gum on the fibers and s·econd is the subsequent sorption of the gum forming the gum­fi ber complex.

The sorption process is assumed to be the Van-der-Walls type. Physical

dispersion forces from numerous "active centers" throughout the cellulose surface set up a force field ca pa blc of attracting and holding the gum molecules. Gum is retained by multiple hydrogen bonding which results in .:i

high degree of irreversible sorption process. The gum may act as flocculant if the pulps arc not saturated or as dcflocculant or dispersant if the pulps arc sa turn ted with gums. The dcflocculating phenomenon may be attributed to the gum acting as an aqueous lubricant which coats the fibers and smoothens out surface roughness, allowing the fibers to pass one - another without entangling.

The GM content of ipil-ipil seeds ranges from 13% to 25%, with mannose to galactose molar ratio of 1.3:1.0 (Unrau 1961, Morimoto et al. 1962, McLeary 1979, Pamplona 1986). The presence of considerable quantities of ash, fibers, proteins and tannin materials along with the GM in ipil-ipil seeds (Pamplona 1986) all add up to make the seeds a potential source of chemical additive to paper.

Pamplona (1986) found that a low concentration of crude or purified gum from ipil-ipil seeds improves burst, tear, tensile and pick resistance and decreases the porosity of sugarcane bagasse pulp handsheets.

MATERIALS AND METHODS

Materials

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

Commercial adhesives guar gum (Guartec and Amatex), starch (Cato 210

and Panda), courtesy of United Pulp and Paper Corporation (UPPC) and Scott Paper Mill, Philippines.

Pulp samples - sugarcane bagasse (SCB), unbleached kraft pine (UKP), kraft cuttings (KC), lauan unbleached kraft, courtesy of UPPC and Paper, Industries Corporation of the Philippines (PICOP).

Preparation of the Paper Adhesive

Process A. The mature, air dried seeds were powdered using a disk grinder and cooked with water at 70-75°C for 30 min, using a seed to water ratio of I:80m/v.

This cooked water suspension of ipil­ipil seed powder containing the dissolved and undissolved components constituted the first form of the gum additive ready for application.

Process B. The seeds were washed well with water to remove impurities, then air-dried and ground to 16 mesh. The ground seeds were placed in a bag made from two layers of an 8-cm diameter cotton cloth. The seeds were subjected to five times repeated water extraction at 80°C each time, using a seed to water ratio of 1:10 m/v. All the extracts were combined and 0.10/o formaldehyde was added as preservative.

The seed aqueous extract constituted the second form of the gum additive ready for application.

Determination of Composition and Properties of the Paper Adhesive

Chemical composition. The AOAC (I 980) standard methods were followed in the proximate analysis of the samples.

3

Some physical properties. The viscosity of the extract was determined at 2s0c using the Brookfield viscometer. The specific gravity and pH were determined using the Westphal balance and Metrohm Herisau pH meter.

Evaluation of the Paper Adhesive

Pulp handsheets. The effects of different concentration levels of the ipil-ipil seed gum additive on the strength properties of paper were determined by incorporating the additive to the laboratory test paper (pulp handsheets), following the T APPi (197B) standard procedures for handsheets pre para ti on, testing and evaluation of properties. Parallel tests were done using commercial starch and guar additives.

Experimental oapcr. A 100% SCB pulp­treated with ipil-ipil seed gum extract was made into experimental paper using the midget Fourdrinier machine. Burst and tear properties were determined.

Commercia 1 paper at UPPC. Using UPPC mill conditions, a furnish consisting of a mixture of 30% UKP and 70% KC with a fin al freeness of 400 ± IO mL CSF was treated with 0.35% ipil-ipil gum suspension to replace guar gum. Paper properties were determined.

The whitewater was analyzed for residual suspended solids. The effluent just before discharging into the river was tested for dissolved oxygen.

Cost Analysis of the Additive Preparation

A cost analysis was made on the seed gum produced. Considered in the

4

analysis were the costs of materials and processing used. .A cost comparison was done with the commercial guar gum additive.

RESULTS AND DISCUSSION

Preparation of the Paper Adhesive

With the use of Tyler sieves, the particle size distribution of the gum powder was found to be as fallows: 7% passed 80-mesh, 44% passed 60-mesh and retained in 80-mesh, 40% passed 40-mesh and retained in 60-mesh and 90/o retained in 40-mesh.

About 96% and 32-380/o recoveries from the dried seeds were attained in the pre para ti on of the seed powder and seed extract gum additive, respectively.

The cooked gum was lemon-colored and viscous. It got spoiled after 2 days of exposure at room conditions. Addition of 0.1 % formaldehyde preserved the gum for at least 30 days.

Determination of the Chemical Composition and Some Physical Properties The ipil-ipil seed powder gum had the same proximate composition as the unprocessed, ground seeds (Pamplona 1986) since the gum was prepared without any chemical treatment on the seeds. Ethanol precipitation, infra-red and chromatographic analyses showed the presence of GM, 13-190/o in the seed powder and 44-540/o in the seed extract additive.

The chemical composition and other properties of the additive arc shown in Tables 1 and 2.

Theoretically, the considerable amounts of ash, fat, crude fiber (in the gum powder only) and protein further enrich the ipil-ipil gum additive with components desirable for paper. The ash may act as - filler and the wax in fat as sizing agent. Along with the galactomannan, the fiber and protein

Table 1. The chemical composition and other properties of the ipil-ipi1 seed powder gum additive for paper

COMPONENT

Water Ash Silica Crude fat Crude fiber Crude protein Nitrogen-free extract Galactomannan gum

Gum suspension

pH Total water insoluble matter

PERCENTAGE (o.d. seed wt. basis)

8.4 3.6 0.1 8.2 9.0

31.5 39.3 13-19

5.7-6.4 62-68%

Effects of Gums from Varied Strains of lpil-ipil to SCB (Tables 3 and 4)

5

can bind cellulose further through their hydroxyl groups. The pH of the gum-water mixture ranges from 4.7 to 6.4. This imparts positive charge to the protein molecules, a form conducive for bonding with the negative cellulose fibers.

The ANOVA showed that highly significant differences existed in the effects of the gum additives on tensile,

Table 2. The chemical composition and other properties of the ipil-ipil seed gum extract additive for paper

COMPONENT

Ash Silica Water-soluble protein Galactomannan gum Other water-soluble matter

Other properties of the gum extract

Dry solid matter Viscosity, 25°C pH Specific gravity

PERCENTAGE

32% 87.7 cp 5.8 0~992

7.2 0.8

2).2 44-54 13.6

Table 3. Effects of 1% dosage each of guar and ipil·ipil gllllS on the strength properties of sugarcane bagasse pulp handsheets

PROPERTY

ADDITIVE. Tensile Index Burst Index Tear2Jndex (Nm/kg) (N/kg) (Nm /kg)

Control (No additive) 32.78 1.24 3.98

Guar gum, Amatex 36.41( 11) 1 1.45 (17) 5.45 (37)

Cunningham seed extract 34.62 (6) 1.52 (23) 4.93 (24) (crude gun)

Native (Copil No. 2) 35.52 (8) 1.56 (26) 4.91 (23) seed extract (crude gum)

Giant K-28 seed extract 36.83 (12) 1.63 (31) 4.91 (23) (crude gum)

Purified CK·28) GM 36.40 (11) 1.60 (29) 3.79 (·5)

1 Number in parenthesis corresponds to percentage increase over control.

6

burst and tear properties of 100% SCB pulp handsheets. The 1 % crude gum extracts of the giant and native strain, guar gum and pure ipil-ipil gum isolate imparted comparable and significant improvement of 8% to 11 % in tensile, 17% _to 31 % in burst (Cunningham included) and 23% to 37% in tear (pure

effect among the galactomannan and other components of the crude gum extract in improving the strength properties of the handsheets. Further testing showed that increasing the level of addition of each gum above 1 % up to 3% did not change the strength properties sign if ican tl y.

Table 4. Effects of guar and crude ipil-ipil gLRn extracts on the strength properties of sugarcane bagasse pulp handsheets

PROPERTY

ADDITIVE LEVEL OF TensHe Index Burst Index Tear Index ADDITIVE (Nm/kg) CN/kg) (Nm/kg)

Control (No Additive) 32.78 1.24 3.98

Guar gum, Amatex 1 36.41 (11>1 1.45 (17) 5.45 (37) 2 35.71 (9) 1.63 (31) 5.37 (35) 3 36.93 (13) 1.60 (29) 4.96 (25)

Copil No. 2 seed extract 1 35.52 (8) 1.56 (26) 4.91 (23) 2 36.85 (12) 1.58 (27) 5.02 (26) 3 36.43 (11) 1.69 (36) 5.02 (26)

Cunningham seed extract 1 39.61 (21) 1.52 (22) 4.9 (24) 2 37.45 (14) 1.66 (34) 5.21 (21) 3 39.18 (20) 1.67 (35) 5.22 (31)

K-28 seed extract 1 36.83 (12) 1.63 (21) 4.91 (23) 2 36.55 (12) 1.49 (20) 5.17 (30) 3 36.84 (12) 1.44 (16) 5.36 (35)

1 Number in parenthesis corresponds to percentage increase over control.

K-28 GM excluded) over the control values.

The decrease in tear due to addition of purified GM was not significant; the dosage necessary to cause any significant change in tear property was not attained. Among the additives, the giant K-28 ipil-ipil extract imparted the highest tensile and burst values. The same dosage of crude and pure GM showed the same level of eff ectivity in increasing tensile and burst. This may indicate the existence of a synergistic

Effects of Varied Concentrations of Different Forms of Ipil-ipil Gum Additive to SCB Treated with Rosin and Alum (Table 5)

The ANOV A showed that at 0.5% dosage, K-28 crude gum extract and guar imparted equivalent and significant increases of 11 % and 12% in tensile, 19% and 20% in burst and equivalent increases of 6% and 12% in tear, respectively; K-28 whole seed powder imparted significant and comparable effects as guar by increases of 10% in burst and 15% in tear.

7

Table 5. Strength properties of SCB treated with 0.5% gum, 1% rosin and 2% alum

ADDITIVE

Control (with 1% rosin size and 2% alum)

K-28 whole seed

K-28 crude gum extract

K-28 dehulled seeds

Corrmercial guar gum, Guartec

Corrmercial, unmodified Panda starch

Tensile Index Nm/kg

39.06

40.33 (3) 1

43.34 (11)

39.65 (2)

43.69 (12)

41.66 (70)

P R 0 P E R T Y

Burst Index N/kg

2.08

2.29 (10)

2.48 (19)

2.24 (8)

2.50 (20)

2.25 (8)

Tear2Index Nm /kg

1.24

1.44 ( 16)

1.32 (6)

1.43 (15)

1.39 (12)

1.32 (6)

1 Number in parentheses corresponds to percentage increase O)ter control.

Effects of the Gums to Lauan Pulp Handsheets of Basis Weight 75 g/m2

(Table 6)

The following ·trends were noted in the ANOVA at 0.5% level of addition: The K-28 crude gum extract and guar comparably and significantly increased tensile by 14% and 20% and increased burst by 6% and 17% and tear by 15% and 22%, respectively, over the control values. The K-28 crude gum extract improved tensile and burst much better than the whole seeds.

Effects of the Gums on the Strength Properties of KC Pulp Handsheets Hav~ng Average Basis Weight of 62.5 g/m (Tables 7 and 8)

The ANOVA showed that addition each of 0.3% guar gum and 0.2% to 0.6% ipil-ipil gum suspension to KC waste paper pulp handsheets imparted equivalent improvements in tensile values, with the 0.3% ipil-ipil gum addition exhibiting the highest improvement over the control (Table 7).

Table 6. Average strength properties of lauan pulp handsheets treated with 0.5% gum, 1% rosin and 2% alum

P R 0 P E R T Y

ADDITIVE Tensile Index Burst Index Tear2Index Nm/kg N/kg Nm /kg

Control Cwith-1% rosin size and 2% alum) 48.0 2.58 1. 76

K-28 whole seeds 49.0 (2) 1 2.30(-11) 1.96 (11)

K-28 crude gum extract 54.8 (14) 2.73 (6) 2.03 (15)

Corrmercial guar gum, guartec 57.7 (20) 3.03 (17) 2.14 (22)

1 Number in parentheses corresponds to percentage increase over control.

8

Table 7. Effects of K-28 ipil-ipil gum suspension on the tensile strength of kraft cuttings pulp handsheets

ADDITIVES

Control (with 1% rosin size and 2% alum)

K-28 ipil-ipil seed gum suspension

Guar gum, Guartec

Cationic starch, Cato 210

CONCENTRATION (%)

•

0.2 0.3 0.4 0.5 0.6

0.3

0.3

TENSILE INDEX (Nm/kg)

59.23

64.95 (10) 1

65 .12 ( 10) 60.60 (2) 61.90 (4) 63.27 (7)

61.07 (3)

58.95 (-0.5)

1 be . Num r 1n parentheses corresponds to percentage increase over control.

Table 8. Effects of guar gum on the strength properties of kraft cuttings pulp handsheets

P R 0 P E R T Y

ADDITIVE CONCENTRATION Tensile Index Burst Index Tear Index (%) Nm/kg N/kg Nm2/kg

Control (with 1% rosin size 57.69 2.90 9.55

and 2% alun>

Guar gun, Guartec 0.2 63.01(9) 1 3.35(12) 9.20(-4) 0.3 67.89(18) 3.51(21) 8.42(-12) 0.4 62.64(9) 3.83(31) 8.09(-15) 0.5 67.59(17) 3.82(32) 8.09(-15) 0.6 74.24(29) 4.39(51) 7. 18(-25)

K~28 Ipil·ipil seed gun suspension 0.3 67.15(16) 3.59(24) 7 .87( -18)

Cationic starch, Cato 210 0.3 60.06(4) 3. 13(8) 9.3(-3)

1 Nunber in parentheses corresponds to percentage increase over control.

In a separate trial using another batch of KC pulp to prepare handsheets treated with varied concentrations of guar and 0.3% each of ipil-ipil gum and cationic starch, the ANOV A showed that the 0.3% ipil-ipil gum significantly improved tensile strength by 16% and burst strength by 24% over the control. Here, the 0.3% ipil-ipil gum imparted equivalent improvements of 9% to 18% in tensile as that of the 0.2% to 0.5% guar gum and equivalent increases of 21 % ro 32% in burst as that of the 0.3% to 0.5% guar gum. As the gum strengthened fiber-to-fiber bonds, the intrinsic strength of the KC fibers could have been exceeded, giving way to easy tear as shown by the decreases in tearing strength based on the control values (Table 8).

9

Comparatively, addition of 0.3% cationic starch did not significantly improve the tensile and burst strengths of the sheets.

Effect of Gums on the Strength Properties .of Unbleached Kraft (UKP) Pulp Ha~dsheets with Basis Weight of 62.5 g/m •

The ANOV A showed that ipil-ipil gum suspension of 0.2% to 0.6% concentration and 0.3% guar gum imparted comparable improvements both in tensile strength by 6% to 12% and burst by 17% to 33% over. the control using 100% unbleached, long­f ibered softwood, virgin kraft pulp (Table 9).

Table 9. Effects of ipil·ipil K·28 seed gum on the strength properties of unbleached kraft pine pulp handsheets

ADDITIVE

Control (with 1% rosin size and 2% alum)

K-28 ipil·ipl seed gum suspension

Guar gum, Guartec

Cationic starch, Cato 210

CONCENTRATION (%)

0.2 0.3 0.4 0.5 0.6

0.3

0.3

Tensile Index Nm/kg

51.59

54.46(6) 57.28(11) 55.72(8) 57.54(12) 57.83(12)

56.93(10)

55.05(7)

1 Number in parentheses corresponds to % increase over control

P R 0 P E R T Y

Burst Index N/kg

2.88

3.47(20) 3.62(26) 3.36(17)

3.83(33) 3.53(23)

3.85(34)

3.37(17)

Tear Index Nm2/kg

19.15

17. 95( ·6) 18.56(-3) 17.12(-11)

17.50( -9) 16.96(·11)

17.20(-10)

19.44(2)

10

Effect of Gums on the Strength Properties of UKP-KC Pulp Handsheets

The ANOVA showed that the ipil-ipil gum added at varied concentratiens significantly differed in their strengthening effects on the pulp mixture containing 30% UKP and 70% KC. The 0.2% to 0.4% ipil-ipil gum suspension and 0.3% guar gum imparted equivalent and significant increases in tensile index from 9% to 11 % over that of the control (Table 10).

Results indicated that the ipil-ipil seed gum additive could be used in acid _(pH 4.5-5.0) or near neutral furnish (pH 7.5-8.0) to dry-strength UKP-KC paper at UPPC (Table 11 ).

Application of the lpil-ipil Seed Gum to Experimental Paper

Among others, the factors considered in developing specific properties in the finished paper are the types, proportion and amount of fibers, type and

Table 10. Effects of ipil·ipil (K-28) seed gum on the tensile and tear properties of mixed unbleached kraft pine-kraft cuttings pulp handsheets

ADDITIVE

Control (with 1% rosin size and 2% alum)

K-28 ipil-ipil seed gum suspension

Guar gum, Guartec

Cationic starch, Cato 210

CONCENTRATION

0.2 0.3 0.4 0.5 0.6

0.3

0.3

P R 0 P E R T Y

Tensile Index Tear2Index (Nm/kg) (Nm /kg)

60.23 12.9

65 .87(9) 1 11.88(-8) 67.05(11) 11.85( ·8) 66.01( 10) 11.88( ·8) 67. 71(2) 10.69(-17) 61.03( 1) 11.52(·11)

65.40(9) 12.16(-6)

57 .84(-4) 13.33(3)

1 Number in parentheses corresponds to percentage increase over control

Effects of Changing the Stock pH

The ANOV A showed that at different pH, the tensile values of the ipil-ipil treated UKP-KC pulp handsheets were not significantly different from each other but each was significantly higher than the control values at the same pH level.

The tear values of the control handsheets did not significantly change upon addition of 0.3% ipil-ipil gum at varying pH.

methods of application of the non­fibrous additives; variations in mechanical treatment of the stock, conditions during sheet formation, pressing, dry.ing, calendering, design of the paper machine, and the use of special finishing operations. Hence, the gum additive is but one of the many factors that affect the properties of the finished paper.

Using the FPRDI midget Fourdrinicr machine, sugarcane bagasse experimental paper treated with 0.5%

11

Table 11. Effects of varying pH on the performance of K-28 ipil-ipil seed gllll as strengthening agent to UKP-KC pulp handsheets

pH

4.5

5.0

5.5

6.0

6.5

7.0

7.5

8.0

ALUM-TREATED

Tensile Index (Nm/kg)

71.52

65.53

74.06

69.74

71.65

72.50

65.95

71.04

(Control>

Tear2Index (Nm /kg)

10.06

10.30

9.41

10.56

10.57

11.69

10.57

11.20

ALUM + 0.3% IPIL·IPIL SEED GUM SUSPENSION

Tensile Index Tear2Index (Nm/kg) (Nm /kg)

77.89( 9) 1 9.89(-2)

75.87(16) 10.30( 0)

75.50( 2) 9. 76( 4)

74.54( 7) 9.86(-7)

73.86( 3) 10.88( 3)

73.27( 1) 11.59(-0.8)

76.72(16) 10.23(-3)

76.40( 8) 10. 71 (-4)

1 NL1T1ber in parentheses corresponds to percentage increase over control at thE same pH level

ipil-ipil K-28 seed gum extract, I% rosin size and 2% alum exhibited improved burst of 6% and tear of 7% over the control (Table 12).

Application of the K-28 Ipil-Ipil Seed Gum to Commercial Paper

The final test on the performance of a

paper additive is determined from the properties exhibited by the finished product which in reality are affected by the interplay of numerous mill conditions, including the type of process-water used during its manufacture. The gum is a chemical entity and the presence of interfering

. processes can render it ineffective as a strengthening agent to paper.

Table 12. Effects of K-28, ipil·ipil seed gum extract on the burst and tear properties of sugarcane bagasse paper

PAPER

Control (no additive)·

Ipil·ipil seed extract treated (0.5% level of addition)

Ipil-ipil seed extract plus rosin (1%) and alum (2%) treated

DENs13v (g/cm )

0.453

0.466

0.470

BASIS W~IGHT (g/m )

92.70

92.86

90.76

1 Number in parentheses corre~ponds to percentage increase over control

BURST Ckp)

84.63

93.08(10)

89.63(6)

TEAR (Nm)

(Cross (+) and machine(-) directions)

(-) 98.56 (+)113.27

(·)110.60(12) 1

(+)114.90(1)

(·)101.99(4) (+)125.50(11)

12

For sack paper, tearing strength, tensile breaking length, tensile energy absorption (TEA)· and Cobb test are important properties monitored in the mill. All these properties measure the durability and serviceability of paper that are repeatedly strained in response to imposed load.

a. The mill trial run for cement bag paper

lpil-ipil gum-treated paper weighing 52.8 tons were produced; the properties are shown in Table 13. _The tear, tensile energy absorption and Cobb test values were Within the acceptable mill standard for Class A and B commercial extensible sack paper.

b. Analysis of the wastewater after the mill trial run

During the mill trial run, ipil-ipil gum­treated paper produced whitewater with suspended solids I 0% lower than when guar gum was utilized. This means a possible retention of more fine particles, possibly as f inc fibers in the paper sheet when guar gum is replaced by ipil_-ipil gum.

The dissolved oxygen of the effluent discharged to the river amounted to 4.0.

Cost Analysis Study

The prime cost of the ipil-ipil gum produced amounted to P22.20/kg. The expenses were distributed as follows:

Table 13. Average physical properties of extensible sack paper treated with ipil-ipil seed gum suspension

PROPERTY 1 CONTROL IPIL-IPIL STANDARD ACCEPTABLE TREATED DEVIATION MILL VALUE

Basis reight 102.0 100.28 (g/m)

Tear MD 121.0 126.57 7.40 120.0 (g) CD 144.6 155.12 7.50 150.0

Tensile MD 5.05 5.55 0.41 4.8 (kg/15 mm)

Stretch MD 9.72 11.09 0.73 (%)

TEA MD 21.9 24.76 2.69 21.0 (kg-cm~2 100 cm

Stiffness MD 106 78.00 6.50 CD 127 111.0 14.12

Porosity 32.3 27.00 3.25 (sec/100 mL air)

COBB Test 29.8 30.12 0.89 30.0 (g)

% Moisture 7.2 7.99

1 MD - machine direction; CD - cross direction

Cost of seed, CRM Cost of labor, CL Power consumption, CP Hauling cost, CH

P21.18 0.32 0.64 0.06

P22.20/kg , ipil-ipil gum

The landed cost of imported guar gum was P31.00/kg when this experiment was conducted in 1987. This means a saving of at least PS/kg if ipil-ipil gum is sold at P26/kg in the mill.

A mill manufacturing 100 tons/day of dry-strengthened sack paper using 400 kg gum, can save about P600,000 only for expenses on gum in a 300 days/ year- operation if ipil-ipil gum is substituted for imported guar gum.

If the cost of ipil-pil seeds can be . reduced when much of it becomes available, then the cost of gum will be considerably lowered.

CONCLUSIONS

• A gum additive, similar to guar gum in strengthening effects on tested samples of commercial SCB, lauan kraft, UKP and KC pulps can be processed from seeds of locally grown giant ipil-ipil t~ees.

• The strengthening property of the gum to UKP-KC pulp remains unchanged within the pH range of

LITERATURE CITED

13

4.5-8.0, indicating that the gum may be used in acid or neutral stock.

• Other benefits in using the ipil-ipil gum to sack and other types of dry­strengthened paper are worth exploring.

• A low amount of residual suspended solids in the whitewater indicates the gum's ability to act as retention aid for fine fibers in paper.

RECOMMENDATIONS

• Improve the performance of the ipil­ipil gum by producing very fine gum powder. In this form, the water-soluble matter will be, increased considerably, besides the possibility of farming a stable colloid when cooked with water.

• Modify the gum to improve viscosity, increase the water-soluble matter, stability and performance as a bonding agent between fibers in paper, and prolong the gum's shelf life.

• Optimize all the mill conditions while .utilizing the gum for the production of bag, wrapping, printing and specialty paper.

• Study other sources of the gum for use as paper additive.

ASPINALL, G. 1983. The polysaccharides V.2. Academic Press. New York.

ASSOCIATION OF OFFICIAL ANALYTICAL CHEMISTS (AOAC). 1980. Official methods of analysis. 13th ed. W. Horwitt (ed.). The Assoc., Washington D.C. 125, 220-223.

MCLEARY, B.V. 1975. Alpha-D-galactosidase activity and galactomannan and galactosyl sucrose oligassacharide depletion in germinating legume seeds. Phytochem. 13: 1747-1757.

14

. 1979. Enzymic hydrolysis, fine structure and gelling interaction ------of legume seed D-galactomannans. Carbohyd. Res. 71: 205-230.

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

PAMPLONA, B.S. 1986. Some properties and use of the ipil-ipil [Leucaena leucocepha/a (Lam.) de Wit] seed gum. M.S. thesis. UPLB.

SWANSON, J.W. 1956. Better adhesives and fiber bonding: the need for further research. T APPi 44: 257-269.

TECHNICAL ASSOCIATION OF THE PULP AND PAPER INDUSTRY (TAPPI). 1978. T APPi testing procedures. Atlanta, Ga., USA. T 205-68-81; T 220-os-7 l; T459-02-75; T 460-os-75.

UNRAU, A.M. 1961. The constitution of galactomannan from seeds of Leucaena glauca. J. Org. Chem. 26: 1097-3101.

FIELD SERVICE TESTING OF GROCERY PRODUCT PALLETS FROM COCONUT (Cocos nucifera L.) LUMBER

Lolita V. Villavelez 1

ABSTRACT

Field service tests of grocery pallets from coconut lumber were conducted among three softdrink manufacturers in the Philippines. Results showed that cocowood pallets surpassed the performance of pallets from commercially-used species.

Preservative treat11Jent on cocowood pallet materials did not significantly af feet their field performance. However, the treatment lowered the resistance of lead boards to damage but not thoseof the interior decks and stringers.

Economic and cost-benefit analysis showed that cocowood pallet-manufacturing business could be highly profitable.

INTRODUCTION

The pallet is important in the unit load system. It allows mechanical handling of the load from the production line to the distribution chain in exactly the same form. Incff iciency in these operations adversely affects the transport and distribution cost, thus bearing directly on the firm's profits.

Among the traditional materials used in pallet manufacture are tangilc [Shorea polysperma (Blanco) Merr.], lauan (Shorea spp.) and apitong (Dipterocarpus grandiflorus Blanco). But their dwindling supply poses a problem to the pallet manufacturers and particularly the beverage firms, which are heavy pallet users. This, coupled with a nsmg demand for wooden pallets, has increased the pallet cost.

Nevertheless, the problem can be addressed through: 1. improved pallet design and construction to prolong service life, and 2. the use of substitute wood species for traditional species. Pallets can be fashioned out of any wood species depending on the intended usage. If a low-cost pallet can be designed enough to withstand normal handling and stacking load, a large potential market is assured.

Research at the Forest Products Research and Development Institute (FPRDI) showed that expendable and permanent types of pallets can be manufactured from unproductive coconut trees. A laboratory evaluation (Villa vclez 1986) showed that cocowood is a prom1smg material for pallet manufacture. This study verified the

Researcher. Furniture, Wares and Packaging Division, FPRDI, DOST, College, Laguna 4031.

~--

16

results of that evaluation through a field service test:

Objectives

1. To validate the technical and economic viability of using coco wood for pallet manufacture in commercial scale.

2. To identify potential adoptors of the cocowood pallet technology.

Review of Literature

The FPRDI has conducted a number of studies on coco stem utilization since early 1979. Results indicated that coco trunks can be converted into lumber either manually or mechanically. However, entrepreneurs hesitate to venture into commercial scale coco stem processing for lack of information on its economics.

Coco trunks can be converted into lumber through several methods. But the most appropriate in the countryside is the use of the two-man-ripsaw ra thcr than the axe and the bolo which produce rough-surfaced and unsquare­dimensioned lumber. More wasteful and with high operational cost is the use of the chainsaw (Quinones 1983).

A two-man-ripsaw yields lumber of good and acceptable quality, which compares well with lumber from wood in the market, i.e., with uniform thickness and width, and smooth surfaces. It also gives higher lumber recovery than either axe or bolo which arc traditionally used in most rural areas of the country (Quinones 1983).

A 24-m long, 22-cm diameter coco tree can give a potenti43I gross volume amounting to 0.90 m (385.84 bd ft).

The gross volume of a 3-m long and 22-cm diameter tree is about 0.114 m3 ( 48.34 bd ft).

Using the two-~an-ripsa w, a team can produce 0.114 m (48.34 bd ft) and 2.54 cm thick lumber or 0.228 m3 (86.68 bd ft) and 5 cm thick lumber a day at a speed of 4572 cm2/15-20 min (area covered). The average volume recovery is 50%. Rate of production and volume recovery are affected by the trunk quality and the extent of the hard and soft portions. The very soft part of the trunk is not good for lumber, while most of the butt arc hard lumber. Nevertheless, though lumber recovery is increased, the hard portion easily dulls the saw, thus affecting production rate (Eala and Tamolang 1976).

Eala and Alcachupas (1983) reported that in the cost of trunks delivered to the sawmill, 33.58% represents the raw materials component, and 66.41 % that of the operational cost of harvesting (viz., 19.90% direct labor, 15.33% energy, 10.78% supplies and materials, 9.48% depreciation and 10.20% direct overhead).

In a pioneering study, Villavelez (1986) tested pallets made from cocosoft, cocohard and tangile through drop and inclined impact tests. Cocosoft pallets generally performed as well as tangile pallets. Cocohard pallets, on the other hand, were inferior to both cocosoft and tangile pallets.

METHODOLOGY

Suney and Selection of Cooperators

A field survey was conducted to identify cooperators for this study. It was found that several business establishments were in dire need of

pallets. These included Shell Chemicals, Caltcx Philippines and pharmaceutical firms such as Allied Pharmaceuticals and Metro Drug. The beverage industry was found to be the heaviest users of pallets.

Three major beverage producers in the Philippines were selected as end users/ cooperators for the study: Cola-Cola Bottlers in Calamba, Laguna; Pepsi­Cola Bottlers in Muntinlupa, Metro­Manila; and Cosmos Bottling Corp. in San Pedro, Laguna.

The FPRDI and the selected clientele signed a Memorandum of Agreement (MOA) to carry out the field service test.

Fabrication of Prototype Pallets

Three sets of experimental cocowood pallets were fabricated according to the cooperators' specifications. Cola-Cola ordered a 36 x 36-inch reversible iype with flush stringers; Pepsi-Cola, a 39.37 x 40-inch reversible type with flush stringers; and Cosmos Plant, a 54 x 42-inch non-reversible type with flush stringers.

Of the 60 pallets field-tested, 30 were treated with pentachloro-phcnol

17

solution while the other half remained untreated.

Field Service Testing and Monitoring

The pallets were equally distributed among the three companies for service­lif e testing. Service performance was riloni tored for 7 months. The test duration was based on the suggestions of the yardmen in charge of pallet use in the plan ts.

Data Gathering

On the seventh month, the pallets were retrieved from the field and brought back to the laboratory for physical inspection and evaluation of degree of damage sustained while in service.

Only the pallets at the Cosmos and Cola-Cola Plants were retrieved. Those at the Pepsi-Cola Plant were all misplaced due to the plant's irregular operation.

After being stack-piled in the laboratory for one month, the pallets were assessed for the degree of damage through a nominal rating used in an earlier test (Villa velez 1986).

Point Distribution Nominal Rating Visual Quality Rating

2.5 No damage (ND) Splits, 2.54 cm less

2.0 Slight damage (SD) Splits more than half-way and slight cracks

1.5 Moderate damage (MD) Cracks less than 0.635 cm width, loosened nails

1.0 Heavy damage (HD) Cracks more than 0.635 cm width, popping nails

0.5 Unserviceable (US) Beyond repair

18

In the damage assessment, the following were considered important:

Acceptable Damage Severe Damage Failure

1. Damage not requiring any repair

1. Shattering/partial loss of a lcadboard

1. Severe shattering or total loss of a lead board

• Splitting thru the nail lines pushing at the back of the lead board

• Minor prying-up of the edge of leadboard

Statistical Analysis

The Kruskal-Wallis One Way Analysis of Variance was used to determine the numerical difference between the treated and untreated pallets.

RESULTS AND DISCUSSION

Evaluation of the Field Senice Test

The summary of test results is shown in Table 1. Of the 60 pallets fielded for testing, only 20 were retrieved for the final evaluation. Of the 20 pallets evaluated, 4 pallets each of the treated and untreated samples had no damage after 7 months of excessive use; 3 treated and no untreated samples sustained severe damage. No pallet became unserviceable during the test period (Table 2).

After the service test, interior deckboards (intermediate deckboards) exhibited more damage than the edge boards and the stringers of treated materials.

Results of the K-W Test indicated that treated and untreated pallets did not

significantly differ in damages incurred by pallet components and fastenings. This may be due to the inherent physical property of the cocowood lumber. As the wood dries up, the fibers hold on fast to the fasteners. As the moisture is removed, the cells close in. The results of the test arc reflected in Tables 1 and 2.

Cost Analysis

An economic feasibility study was undertaken. Moreover, a comparative cost-benefit analysis was made to assess the economics of utilizing the technology (Table 3).

The pallets made from commercial lumber lasted for 2 months, while the cocowood pallets were still serviceable even after 6 months. Fabrication of the cocowood pallets appeared cheaper (Table 4) mainly due to cheaper raw materials used. Initial cost per pallet of traditional lumber was P280.00; that of cocowood was only .P200.00. Replacement cost for the traditional pallet was much higher (Table 3). With the values obtained from the feasibility study and from Table 1, it seems that a cocowood grocery pallet is more economical than a commercial pallet.

19

Table l. Results of field-testing the pallets

REPLICATE COMPONENTS FASTENING NO. Leading Interior Stringer Nail Pulled Wood

Edge Deck board Broken Splits Deck board

UT l 2 2.5 2.5 2.5 2.5 2.0 UT 2 2 2.5 2.5 2.5 2.5 2.0 UT 3 2.5 2.5 2.5 2.5 2.5 2.0 UT 4 2.5 2.5 2.5 2.5 2.5 2.5 UT 5 2.5 2.5 2.5 2.5 2.5 2.5 UT 6 2.0 2.0 2.5 2.5 2.5 2.0 UT 7 2.5 2.5 2.0 2.5 2.5 2.0 UT 8 2.0 2.0 2.0 2.5 2.5 2.0 UT 9 2.5 2.5 2.0 2.5 2.5 2.0 UT 10 2.5 2.5 2.0 2.5 2.5 2.0 Average 2.30 2.40 2.30 2.30 2.5 2.40

T I 2.5 2.5 2.5 2.5 2.5 2.5 T 2 2.0 2.5 2.0 2.5 2.5 2.0 T 3 1.0 2.0 2.5 2.5 2.5 2.0 T 4 2.5 2.5 2.5 2.5 2.5 2.0 T 5 2.5 2.5 2.5 2.5 2.5 2.0 T 6 2.5 2.5 2.5 2.5 2.5 2.0 T 7 1.0 2.5 2.0 2.5 2.5 2.0 T 8 1.0 2.5 2.0 2.5 2.5 2.0 T 9 2.5 2.5 2.0 2.5 2.5 2.0 TIO 2.5 2.5 2.0 2.5 2.5 2.0 Average 2.0 2.45 2.30 2.50 2.50 2.05

Table 2. Physical assessment of the retrieved pallets

COSMOS PLANT COLA-COLA PLANT Items Treated Untreated Treated Untreated

No damage 3 3 l 1 Acccpta ble damage I 2 3 4 Severe damage 1 0 I 0 Failure 0 0 0 0

20

Table 3. Comparative cost benefit analysis of commercial pallets vs. cocowood pallets

A. Pallet life

Cost/pallet Initial cost ( 12,000 pieces) Maintenance Replacements

Initial cost Maintenance Replacement

Source: Cortigucrra 1990.

COMMERCIAL PALLETS

2 months

p 280

3,360,000.00 30,855.00

1,400,000.00

3,360,000.00 30,855.00

3,390,855.00

COCO WOOD PALLETS

6 months

p 280

2,400,000.00 25,300.00

400,000.00

2,400,000.00 25,300.00

2,425,300.00

Table 4. Estimated production cost* of cocowood pallets vs. tangile pallets

DETAILS

Lumber

Deck board Stringers

Nails

Labor

Total Cost

PALLET COCO WOOD

Unit Total Price Cost

6.50 101.01 4.75 31.16

22.00/kilo 16.60

30.00/pallet 30.00 (Piece meal)

178.67

* Cost was based in 1989 price of lumber materials.

TANGILE

Unit Total Price Cost

8.50 132.39 8.50 55.76

22.00/kilo 16.50

30.00/pallet 30.00 (piece meal)

245.35

CONCLUSIONS

• Cocowood pallets can surpass the performance of pallets made from commercial species.

• Preservative treatment does not have a significant effect on the field performance of cocowood pallets. Although it does not affect the interior decks' and stringers' resistance to damage, it lowers the Icadboards' resistance to damage.

• Fastening docs not significantly aff cct the service performance of tr ca tcd and untrca ted samples.

REFERENCES

21

• Coco wood pallet manufacturing is highly profitable. The cocowood pallet is cheaper by P80.00 than pallet from traditional species.

RECOMMENDATION

• The pallet can be designed using I x 4-inch deckboards to maximize the use of cocowood.

COR TIGUERRA, E.C. 1990. Feasibility study on the production of cocowood grocery product pallets. Terminal Report. FPRDI Library, College, Laguna.

EALA, R.C. and F.N. T AMOLANG. properties of coconut timber. College, Laguna, Philippines.

1976. Exploratory study on the machining Unpubl. Report. FORPRIDECOM Library,

and P.C. ALCACHUPAS. 1983. Cost of coconut lumber production. -----FPRDI J. 12(1&2): 16-21.

QUINONES, D.C. 1983. Backyard lumbering of coconut trunks with two-man-rip saw. FPRDI J. 12(1&2): 7-14.

VILLA VELEZ, L.V. 1986. Performance evaluation of grocery product pallets from coconut (Cocos nucifera Linn) lumber. FPRDI J. 15(1 & 2): 26-40.

THE TAXONOMY AND WOOD ANAT01\1Y OF THREE PHILIPPINE Anisoptera (PALOSAPIS GROUP) SPEQES (DIP'f.EROCARPACEAE)

Arsenio B. Ella, Ramiro P. Escobi11 and Mario AI. Marnz zo 1

ABSTRACT

The taxonomy and wood anatomy of three Philippine Anisoptera species were stlldied for their proper identification.

Keys to species identification were based 011 the essemial diagnostic characters of tlze leaves and flowers and field characters, of bark and blaze (slash) selected from extensive descriptions made on each taxon and 011 actllal field and hcrbarillm studies in the provinces of Quezon. Laguna, Zambales and Zamboanga de/ Sltr. Obsenation on species ecology was likewise touched as added information that could lead to preliminary identification.

The woods are distinctive on account of their yellowish or light yellow color. Anatomically, the striking features of palosapis wood are: 1. presence of di/fuse and very few resin canals which are typically smaller or about half as large as the pores, surrounded by parenchyma and distribllted throllghout the wood or in pairs; and 2. parenchyma apotracheal (diffuse or in short tangential lines); least dense in A. costata Korth. and fairly in A. a urea Foxw. sometimes tending to be paratracheal as narrow vasicentric to slightly a/if orm apart from those associated with intercellular canals. Ray ( multiseriates) are heterocellular; sheath cells are highest in A. cos ta ta (ave. 1.094 mm) and lowest in A. a urea (ave. 0.7 4 mm). Fibers are generally thin-walled with bordered pits.

INTRODUCTION

Amon~ Philippine trees, the dipterocarps have been subjected to numerous researches along basic and applied disciplines. This is because dipterocarps arc the mainstays of Philippine forestry and arc the primary sources of timber for local wood-based industries and for export.

Of the various taxonomical and anatomical studies on this species, the

foremost is the updated information by Rojo (1979). Such information is also cited in The Philippine Recommends for Dipterocarp Production ( 1985) wherein the group of Anisoptera has been reduced to only three species, namely: Anisoptcra aurea Foxw. (dagang), A. costata Korth. (Mindanao palosapis) and A. tlwrif era (Blanco) Blume spp. tlwrifera (palosapis) (Ta blc 1). The former Anisoptera brwmea

1 Researchers, Housing and Materials Division, FPRDI, DOST, College, Laguna

4031.

23

Table L List of presently recognized Philippine Anisoptera species (Palosapis group)

ACCEPTED NAME PREVIOUSLY USED NAME AND/OR SYNONYM

OFFICIAL COMMON NAME

Anisoptera aurea Foxw. same Dagang

A. costata Korth. A. mindanensis Foxw. Mindanao palosapis

A. thurijera (Blanco) Blume ssp. thurijera

A. thurijera (Blanco) Blume (i.e. as full species)

Palosapis

Foxw. (Afu) has been reduced to synonymy with the present A. thurifera ssp. thurif era (palosapis), thus refuting the four species previously enumerated by Salvosa (1963). A. brunnea, therefore, is considered dubious and docs not merit official recognition yet under the Philippine representatives of the genus.

A. thurifera ssp. thurifera is widely distributed in all the lumbering regions in Luzon, Mindoro and Negros, while A. costata is obtainable in small quantities in Mindanao (Zamboanga) and Basilan Island. A. aurea is obtainable in Quezon, Camarines Norte and Sur, and Negros.

Anisoptera species are large to very large forest trees with straight regular bole and a diameter (dbh) of 40-120 cm. They have prominent, thick, tall, straight, rounded buttresses. The wood has a thick bark, with an irregular surface section fissured and flaking but not curling. The inner bark is tangentially laminated. The heartwood appears to be yellowish-brown or straw with brownish streaks when fresh.

Generally, this group of species is resinous. It is the source of the resinous oil popularly known as "oil of

palosapis". The resin is very similar to "balau" from apitong (Dipterocarpus grandiflorus Blanco). It is obtained in the same manner and serves the same purpose, i.e., in the manufacture of varnish which makes a brilliant, tough and durable coating (Brown 1921). Clover (1906), as cited by Brown (1921), said that the oil of palosapis resembles that from apitong, but dries much faster. It is also light colored, apparently homogenous in compos1t10n and so viscous that it can hardly be poured (Ella 1987).

The wood from the palosapis group has long been known in the local market under the trade name "palosapis". The bulk of timber production comes from A. thurif era ssp. thurifera. The wood is modern tely hard and classified as a general utility material used for door, furniture, JOrnery and interior decoration. It is also used for ship decking, vehicle bodies, building construction, plankings, veneer and plywood. It is suitable for wooden tank, tight cooperage, and to a lesser extent, for bats and handles of household utensils.

Preliminary studies made by Reyes (1938) described the wood structures of

24

Anisoptera species as follows: with pores solitary, occasionally in pairs; they touch rays on one or two sides, small to moderately large; perforations simple; wood parenchyma diffuse and vasicentric; and resin canals (intercellular canals) diffuse, filled with whitish resin about half as large as the vessels. Meniado et al. (1975) revealed that differentiating the species of palosapis is hardly possible but in the splinter test, ash appears brown in dagang, grayish in Mindanao palosapis, and grayish white in palosapis.

Objective

To describe Philippine Anisoptera trees based on their: a. macro and micro wood structures, and b. botanical characteristics for reference in their iden tifica ti on.

MATERIALS AND METHODS

A. Taxonomy /Dendrology

Individual taxon in the "palosapis" group of timbers (Dipterocarpaceae) was studied and observed from preserved herbarium vouchers lodged at die CLP2 and the Museum of Natural History (CAHUP), UPLB, College, Laguna. This was supplemented by field observation and study of freshly collected botanical material and field characters of individual trees, viz., bark type and

2 International abbreviation of the Forest Products Research and Development Institute (FPRDI) Herbarium in College, Laguna, Philippines.

blaze (slash), buttresses, and so on in the provinces of Laguna, Quezon, Zambalcs and Zamboanga del Sur.

A key to species identification was constructed based on herbarium and field observation of newly-collected materials following standard botanical practice. The nomenclature was that of Ashton ( 1982), while the official common names used conformed with those of Salvosa (1963) and Rojo (1979). Data and information from li tcrature were incorporated where the species were most abundant in the country and hcrbarium specimens were . not available for examination or field observation of standing trees was not possible.

Linc drawings of important morphological characteristics of the lea vcs were also prepared to distinguish one species from the other.

B. Wood Anatomy

Wood samples of Philippine Anisoptera used were obtained from the Forest Products Research and Development Institute (FPRDI) and the Forest Management Bureau (FMB). Additional. wood samples of dagang were directly collected from the Quezon National Park, in Pagbilao and Atimonan, Quezon; palosapis from the concession area of Acoje Mines, Inc. in Sta. Cruz, Zambales; and Mindanao palosapis from the logging concession of Zamboanga Wood Products based in Malubal, R.T. Lim, Zamboanga del Sur. The collection data are listed in Ta blc 2.

From the said materials, wood blocks were cut and designed according to their true planes (cross, tangential and radial) and softened in boiling water until water-logged for microtome sectioning. Section slides were prepared in accordan~e with the

25

Table 2. Collection data of Anisoptera species sampled for wood anatomy

SPECIES COLLECTOR

Aniso pte rtl. aurea M. Lagrimas Foxw. (dagang) M. Lagrimas

M. Lagrimas

M. Lagrimas F. Cortes Penas, Abellanosa and Soriano

, A. thurijera E.D. Merrill (Blanco) Blume and ssp. thurlf era MM. Curran (palosapis) F. Tamesis

M.M. Curran T.L. Borden E.D. Merrill

A. costata Korth. Whitford and (Mindanao W .L,. Hutchinson palosapis) A.B. Ella and

R.P. Escobin

procedure followed in the Institute (1961)). :fhe process of macerating wood chips for examination of separate elements like measurement of vessel lengths and fiber dimension was accomplished using Franklin's method as cited by Wilson and White (1970).

Information concerning some physical properties of Anisoptera wood were based on the works of Reyes (I 938), Tamesis and Aguilar ( 1958) and Burgess ( 1966). Detaifs for macroscopic examination followed those of Tamolang, et. al. ( 1961) and Dads well et al. (I 947); the microscopic observation was in accordance with that of Tamolang ct al. (1963).

ORIGIN FIELD/ CATALOGUE NO.

Lia vac, Quezon FPRI 145 Famy, Laguna FPRI 368 Basud, Camarines FPRI 175

Norte Infanta, Quezon FPRI 131 Sa mar BF 25973

Camarines BF 21725

Pangasinan BF 8287

Ncgros Occidental BF 20676 Limay, Bataan BF 17585 Lamao, Bataan BF 2128 Mindoro BF 11389 Masinloc, Zambales BF 934

Zamboanga BF 9371

Zamboanga del Sur FPRDI 097

Photographs of the wood blocks' cross sections (magnified !Ox) and radial and tangential sections (80x or higher manifications) were taken to accompany species description.

RESULTS

A. Taxonomy /Dendrology

Key to Species

The following keys to identification of Philippine Anisoptera were based on essential diagnostic characters of the leaves and flowers and field characters of bark and blaze (slash).

26

A. Key to Philippine Anisoptera Based on Vegetative and Reproductive Morphological- Characters

1. Stamens c. 25, nerves at least 15 pairs, petiole and nervation beneath more or less persistently pubescent, leaf undersurface dull yellowish or greenish lepidote, nerves hard I y or not depresse~ above - - - - - - - - - - - - - 2. A costata

1. Stamens 35-47, nerves (10-) 14-18 (-20) pairs, twigs, petiole and nerva ti on beneath pubescent, leaf undersurface grayish to brown lepidote or densely golden lepidote

2. Stamens 37-47, leaves grayish to brown-lepidote beneath - -

3. A. thurifera ssp. thurifera

2. Stamens 35-38, leaves densely golden lepidote - - - I. A.

a urea

B. Key to Philippine Anisoptera Based on Field Characters of Bark and Blaze

I. Outer bark distinctly cream­brown with shaggy persistent flakes - - - - - - - - - I. A. aurea

I. Outer bark dull grayish-brown to greyish brown with flakes that ea'sily peel off from below

2. Blaze cream-yellow, dammar exudation pale-grey - - - - - -

- - - - - - - - 2. A. costata

2. Blaze yellowish-orange, dammar ex uda ti on clear and watery - - - 3. A. thurifera ssp.

thurifera

* Numbers opposite names indicate their order of appearance in the subsequent descriptions of taxa.

Description of Species

Only those characteristics of practical use to foresters, forestry students, field men, forest industrialists, wood users and forest scientists were included. Hence, no details of flowers were given. The leaves and important field characters of the bole, bark and blaze (slash) were emphasized as they proved to be appreciated later by non-botanists (Table 3). However, in the accompanying line-drawings of species, details of the flowers and fruits were shown for reference (Figs. 1-3). Few references on the correct names and synonyms were cited since they were too numerous. Only the original source of each name together with one or two publications of particular significance for the taxonomic status of the species in question were included.

I. Anisoptera aurea Foxw. Dagang

Anisoptera aurea Foxw., Phil. J. Sci. 67 ( 1938) Bot. 271, pl. 1-2. Syn. A. curtisii (non Dyer ex King) Foxw., Phil. J. Sci. 6 (1911) Bot. 225, pl. 41; ibid. 13 (1918) Bot. 181.

Vegetative Field Characteristics

General apoearance: A large tree 40 m high or more. Diameter at breast height to I 00 cm or more. Bole fissured-flaky type, cylindrical ·but sometimes angular at base, straight. Crown hemi-spherical, golden-yellowish at a distance. Fallen leaf undersurface distinctly golden brown. Buttress: Simple, rounded and rather low to ca. l m from the ground. Bark: Distinctively cream-brown with more or less shaggy persistent flakes generally peeling away from below leaving irregular scars, ea. 4 x 8 cm. Blaze (Slash): Inner bark thick, yellowish to yellowish orange to reddish-orange with irregular reddish

: and blaze (slash) features and their characteristics manifestations

BARK BLAZE (SLASH)

Surface Specific Manifesta~ions Color Odor Exudate color type

·th greyish- brown flaky-fissured bark surface studded with cream-yellow; resinous pale-grey; slowly 1sapis> warty lenticels, shallowly with bands of coming as smear

fissured; fissured yellow and on surf ace irregular in section; lighter tissues flakes coming away in time from below

anco) dull-greyish flaky-fissured bark surface studded with yellowish-orange; resinous clear and watery; nurifera brown lenticles; shallowly with bands of coming as smear on

fissured when young becoming yellow and surface irregularly fissured or lighter tissues flaky in time; flakes falling away in time from below

cream-brown flaky-fissured bark surface with more yellowish-orange resinous clear and watery; or less shaggy persistent with bands of slowly coming as flakes peeling away from yellow and smear on surf ace below and leaving reddish to irregular scars pinkish tissues

28

vertical streaks, laminated, with Ii ttle watery dammar exudations from cut portion.

Botanical Characteristics

Twigs densely, persistently pale-brown pubescent, ca. 3 mm in diameter, becoming tcrete, pale brown, rugulosc. Leaf buds to 4 x 2 mm, lanceola te, acute, densely persistently pale-brown puberulent. Leaves 7-11 x 2.5-5.5 cm, oblong or oblanceolate, thinly coriaceous; undersurf ace densely golden lcpidote; base cuneate or sometimes obtuse; acumen to 1 cm long, slender, prominent, down curved and bending over on pressing; nerves densely persistently pale-brown puberulcnt with (15) 18-20 pairs, slender but distinctly elevated beneath, less so distinct above, 50°-65°; secondary nerves obscure or absent; tertiary nerves densely reticulate, evident on both surfaces, midrib densely obscure, · deeply depressed above; petioles 15-27 mm long, slender, prominently genicula te and densely persistently pale-brown puberulcnt. Panicles to 12 cm long, slender, lax, pendent, terminal or axillary, singly (if axillary) or doubly branched; branchlcts to i 5 mm long, bearing up to 3 flowers. Fruit pedicel to 4 mm long, slender, calyx tube to 7 mm in diameter, su bglobose; 2 longer lobes to 10 x 1.5 cm, narrowly spatulate, narrowly obtuse, 3 cm wide at base; 3 shorter lobes to 12 x 2 mm, linear.

Distribution: Laguna, Southern Quezon (formerly Tayabas), Camarines Norte and Polillo Island.

Ecology: In mixed dipterocarp forest, specially on ridges from 100-600 m above sea level. In Quezon National Park (QNP) the species usually occurs in association with Dipterocarpus and Shorea spp. Endemic to the

Philippines. scattered.

Regeneration few,

Local names: Balau (P. Bis.); dagang (Tag., Bik.); dagum (Bik.); domagat {Tag.); malaganga u {Tag.); manapo {Tag.); mayapis (Tag.); payhapi (Tag.); palosapis {Tag., Pang.); siyau (S.L. Bis.).

2. Anisoptera costata Korth. Mindanao palosapis

A. costata Korth; Kruidk. (1841) 67, t. 6, f. 1-9; Bl. Mus. Bot. L ugd. - Bat. 2(1852)42 - Syn. A. mindanensis Foxw. Phil. J. Sc. 13(1918) Bot. 181; ibid 67 ( 1938) 266; Merr. En. Phil. 3(1923) 92.

V egeta ti ve Field Characters

General apoearance: A very large tree 50 m high or more and up to 2 m in diameter breast height. Bole tall, straight and cylindrical. Grows bemi­spherically, rather narrow, fed by a few twisted ascending branches. Fallen leaves medium-sized, relatively broad, pale gray-green on drying with shortly gray-brown scabrid tomentose nerva ti on on the undersurface and petiole, otherwise epilose. Buttress: Few, low up to 2.5 m long, thick, rounded, straight, continuing up the bole as ribs. Bark: Outer surface grayish brown, shallowly fissured; fissured-1.5 m long, irregular section, with 5-15 cm broad flat ridges coming away in thin flakes; studded with warty lenticels ca. 3 mm in diameter; thick. Blaze: Inner bark up to 3 cm thick, thickly laminated, cream and yellow; sapwood creamish white, heartwood pale yellow. Pale gray smears of dammar usually exude from cut portion.

Botanical Characteristics

Twigs of variable thickness, at first frequently angular, becoming minutely

striated or smooth, eterete. Bud 3-5 x 1.5-3 mm, ovoid, somewhat compressed, acute. Stipule ca. 8 x 3 mm, hastate, acute, fugaceous. Leaves 6-18 x 7-11 mm, thinly coriaceous, frequently slightly bullate, oblong to obovate undersurface gray-green epilose to lcpidote to golden or chocolate; base obtuse or broadly cuneate; acumen to 5 mm long; margin not revolute or only slightly so; nerves 8-22 pairs at 60°-70°; petiole 2-4 cm long. Panicles to 20 cm long, terminal or axillary, angular, pendent, doubly or trebly branched, branchlcts bearing up to 5 flowers. Fruit calyx shortly pubescent, tube glabrcscent; tube to 1 x 1.2 cm, globose, tapering gradually to the pediccl, narrowed to 8 mm in diameter at the neck; 2 longer calyx lobes to 16 x 1.5-2 cm. spa tu late, o btusc, ca. 5 mm broad at base; 3 shorter lobes to 20 x 4 mm, variable, hastate, base slightly constricted.

Distribution: Mindanao (one record), in Naganaga, Zamboanga, also found in the concession of ZAMBOWOOD in Malubal, Zambqanga but rare in occurrence. The species also occurs in Borneo, Sumatra, Malaya to Chittagona, Burma, Thailand and Inda-China.

Ecology: The species occurs in mixed dipterocarp lowland forest from 100-600 m. In Malubal, Zamboanga Sur in logged-over concession area of ZAMBO WOOD, the species was observed to be in association with other dipterocarpaceae trees such as Dipterocarpus, Shorea and Hopea spp. along ridges or well-dr.aincd slopes and hill tops. Regeneration is usually scanty and few seedlings have been observed.

Local Name: Baligan (Sul.)

Note: The trees observed in logged-over concession of ZAMBOWOOD, Zambuanga del Sur were in sterile state. The description

29

provided for the paniclcs and fruit calyx were from Ashton (1982).

3. Anisoptera thurifera (Blanco) Blume ssp. thurijera Palosapis

A. thurif era (Blanco) Blume ssp. thurifera stat. & ssp. nov. in Ashton, Card. Bull. Sing. 31 (1978) 15-16; Fl. Mal. Precur. Ser. 1 Vol. 9 ( 1982) 333-334. Basio. Mocanera thurif era Blanco, Fl. Filip. (1837) 446. Anisoptera thurifera (Blanco) Blume, Mus. Bot. Lugd. - Bot. 2 (1852) 42; Foxw., Phil. J. Sci. 67 (1938) 267 (incl. pertinent synonymy)- A. brumzea Foxw., Phil. J. Sc. 6 (1911) Bot. 254.

Vegetative Field Characters

Genera I Appea ranee: Large- to medium-sized tree. Bole with good clear height, straight and cylindrical, grayish white to dull gray-brown or yellowish gray. Crown large and dark colored from a distance. Fallen leaves relatively small-, gray-green lcpidote. Buttress: Simple, thick, low and rounded. Bark: Outer bark dull gray-brown, more or less regularly, shallowly fissured when young, la te·r becoming irregularly f issurcd or scaly. Scales or flakes fall off with age, usually rectangular, ca. I x 4 cm. Exposed portions studded with diffuse, mcdium­sizcd warty lcn ti cc ls. Blaze (slash): Inner bark yellowish­orange-brown, thick to 2.54 cm or more, composed of alternating bands of yellow and lighter colored tissues. Sapwood pale, exuding a clear watery and sticky resin that forms a smear on the cut surface.

Botanical Characteristics

Twigs ca. 3 mm in diameter apically, terete, rugulose, densely persistently

30

pale to chocolate brown lepidote. Leaf bud to 4 x 2 mm, lanceolate gray-green lcpidote. Stipules to 8 mm long, linear. Ltaves 6-15 x 2.5-6.5 cm, thinly coriaceous, elliptic to lanceola te or obovate-oblanceolate; base broadly cuneatc or obtuse; acumen to 1.3 cm long, slender, down-curved and twisting over on pressing; nerves (12-) 14-18 (-20) pairs, slender but distinctly elevated beneath, less so above, arched, at 55°-so0

, with or without short secondary nerves; midrib prominent beneath, obscure, depressed, above; petiole 1.7-3.5 cm long slender. Panicles to 20 cm long, terminal or subterminal axillary, lax, pendent; singly branched, branchlcts bearing to 11 flowers. Fruit pedicel to 3 mm long, short. Calyx tube to 17 mm in diameter, globose; 2 longer lobes to 15 x 1.5 cm, spatulate, narrowly obtuse, ca. 4 mm wide at base; 3 shorter lobes to 30 x 3 mm linear.

Distribution: This is the most widely distributed among the taxa under the genus.

In more seasonal areas of the Philippines. Luzon ( Caga yan, Ilocos Norte, Ilocos Sur, Nueva Ecija, Abra, Nueva Vizcaya, Tarlac, Pangasinan, Bulacan, Zambaks, · Ba ta an, Rizal, Laguna, Camarines, Albay); Sibuyan; Tica<;>; Panay; Negros; Masbate; Samar; Mindanao (Zamboanga).

Ecologv: The subspecies occurs in mixed dipterocarp forest from 100-7 50 m above sea level; very common and often gregarious, re genera ting in secondary forest. In Sta. Cruz, Zambalcs in the concession of Acojc Mines, Inc. found along well-drained areas such as ridges and hilltops in association with other diptcrocarpaccous trees.

Local names: Apnit (Ilk.); bagobaloy (S.L. Bis.); baliuasuas (Ilk.); bariuisuis

(Pang.); dagang (Tag. Bik., P. Bis.) dagang-naputi (Tag.); dagum (Tag.); da yang (Tag.); doyong (Ilk.); du uag (Ting.); duyong (Ilk.); guyong (Ilk.); la uan-pu ti (Tag.); le tis (Tag., Bis., Ilk.); malapaho (Bik.); mayapis (Sbl., Tag.); nininu (lbn.); palosapis (Ilk., Pang., Sbl., Tag.); palosapis (Ilk.); payhapi (Sbl.); Sandana (Tag., Bis.); sinalagan (Ilk.); tabila (Bik.). (Figs. 1- 3).

B. Wood Anatomy (some general characteristics and properties)

l\tacroscopic (Description as a group, Table 4)

Genera 1 Characteristics. Sapwood lighter-colored than the heartwood, which is buff, turning yellowish or light yellow upon exposure or with age; stains readily, often with rose-colored longitudinal streaks; grain generally straight, sometimes crossed or wavy; texture moderately fine to moderately coarse; not glossy, without resinous odor when dry; moderately hard and heavy. Structure (Figs. 4-6): Growth rings indistinct. Pores readily visible to the naked eye, mostly solitary; tyloses present. Parenchyma visible only with a hand lens, typically diffuse which occurs as minute, short tangential bands between rays; the vasicentric parenchyma inconspicuous. Rays of two kinds, uniscria te and m ul tiseria te visible to the naked eye, somewhat broad but narrower than pores. Resin canals v~ry small, diffuse, not visible to the naked eye.

Splinter Test (Ash Test)

This involved the burning of a match­stick size splinter of the heartwood and noting the appearance of the residues. Splinters burned to brown ash in Anisoptcra aurca, grayish in A. cos1a1a and grayish to grayish white in A. thurif era ssp. thurif era.

Table 4. Important macroscopic (including some physical characteristics and properties) and microscopic features for the identification of the "Palosapis" Group ( Anisoptera >

M I C R 0 S C 0 P I C

S P E C I E S COLOR RELATIVE INTERCELLULAR FIBER DIMENSIONS (mm) VESSEL MULTISERIATE RAYS (mm) DENSITY CANALS (Sp. gr.) Fiber Diameter Lumen Cell wall No. per Average Average Pore size Height No. of Parenchyma

Green 12% Length Width Thickness sq. mm Length Tangential Classifi · eel ls MC MC and ave. (mm) Diameter cation wide

(2) (3) (4) (5) (6) (7) (8) (9) (10) (11) (12) ( 13) (14) (15)

Anisoptera See expla· 114. 75 0.577 See expla· 1.7867 0.025 0.009 0.007 7·37 0.5632 0.0740 FS 0.7399 22 More of para· aurea Foxw. nation nation Cave. 18) tracheal forming (dagang) below below to be narrowly

vasicentric to A. thurifera 104.07 0.592 1. 7566 0.025 0.009 0.007 6·20 0.4652 0.0814 FS 0.8518 27 slightly aliform

(Blanco> Blume (ave. 9) apart from those ssp. thurifera associated with (Palosap1sJ intercel lular

canals

A. costata Korth. 111.36 0.583 1. 7503 0.031 0.012 0.009 5·12 0.5773 0.1087 vs 1.094 28 More of apotrac· CM1ndanao palosapis} (ave. 8) heal diffuse

apart from those associated with intercel lular canals

Explanation to column nos.

2. Color · All species have lighter-colored sapwood than heartwood, which is light ochraccous buff (light reddish yellow) with occasional pinkish stripes. 3. Relative density · based on green volume at test and oven-dry weight 4. lntercellular canal typically smaller than the pores and surrounded by parenchyma scattered throughout the wood singly or in pairs and in short tangential

series, occasionally filled with whitish resin ori ;.;A. thurifera i-1. ssp. thurifera. or empty

12.· Pore size classification · ES extremely small; VS very small

w -

32

~(~.'.·.'fo .. IE fv~-4

Fig. 1. Anisoptera aurea Foxw.: 1 fruiting twig; 2 details of a mature leaf; 3 details of fruit; 4 same. wings removed. All based 011 BAL-wznumbercd. (CLP).

Flg. 2. Anisoptera thurifera (Blanco) Blume ssp. thurifera: 1 flowering branch; l details of a mature lead; 3 flower bud; 4 flower details slzm\·ing stamens tnz.i pistil; 5 same portion of calyx removed; 6 fruit; 7 same. lrings removed. A.II based on Escobin-097 (CLP).

Microscopic

I. Anisoptera aurea Foxw. (dagang) (Figs. 7, 10, 13)

Vessels pred©minantly solitary and diffuse; moderately few to numerous, 7-37 (ave. I 8) per sq mm; extremely small to very small, 0.0848-0.412 I mm (ave. 0.2182 mm) in tangential diameter; circular and oval in shape.

Vessel elements extremely short, 0.303-1.52 mm (ave. 0.58 I 8 mm); perforations simple and perforation plates slightly inclined; tyloses present.

33

Parenchyma fairly abundant, apotracheal (generally diffuse and in short uniseria te bands; some appear to be paratracheal that tend to be narrowly vasicentric to slightly aliform, apart from those associated with intercellular canals, banded broadly at 4-9 or slightly more cells wide; strands usually of 4-8 cells (ave. 6).

Rays few to moderately numerous, 3-6 per sq mm (ave. 4); uniseriate, the multiseriate heterocellular, 2-6 cells wide (mostly 5) with 1-4 rarely slightly more marginal rows of square or

Fig. 3. Anisoptera cos ta ta Korth.: J details of mature twigs,· 2 _flower bud; 3 stamens and pistil,· 4 details of stamen,· 5 details of petal; 6 /nut; 7 nut. 2-7 based on Ashton ( 1982); based on Escobin-078 (CLP).

34

Fig. 4. Daga11g (A. aurea Foxw.)

Fig. 5. Palosapis [A. thurifera (Blanco) Blume ssp. thurlf era]

upright cells (sheath cells present); extremely fine, 0.061-0.182 mm wide (ave. 0.085 mm); extremely low to low, 0.2688 mm to 1.3665 mm (ave. 0.74 mm); the uniseriate composed mostly of square to upright cells, extremely fine, 0.0242-0.0485 mm wide (ave. 0.0364 mm); extremely low, 0.044-0.4444 mm (ave. 0.2738 mm) or 4-12 cells high (ave. 6) or occasionally slightly more; ray­vessel pits of ten large, simple, round to elongated.

Fig. 6. Mindanao palosapis (A. costata Korth.)

Figs. 4-6. Pores moderately few to moderately numerous and predo­minantly solitary occasionally in pairs with parenchyma generally di/ fused or sometimes in uniseriate bands as commonly observed in cross section of dagang ~A. aurea Foxw.) ( JOX).

Silica inclusions not observed.

Fibers medium-sized to very long 0.9 to 2.58 mm (ave. 1.78 mm), thin-walled (ave. 0.007 mm); lumen width (ave. 0.009 mm); diameter (ave. 0.0253 mm); non-septate; and with bordered pits in tangential and radial walls.

lntercellular canals extremely small 5-9 )lm or 0.05-0.09 mm (ave. 0.07 mm) in tangential diameter and typically smaller than the pores.

Fig. 7. Dagang (A. aurea Foxw.)

Figs. 7-9. Cross section of Anisoptera ssp. showing almost exclusively solitary pores and tyloses present; parenchyma typically di/ fuse forming short lines from ray to ray (80X).

2. A. costata Korth. (Mindanao palosapis) (Figs. 9, 12, 15)

Vessels moderately few to moderately numerous 5-12 (ave. 8) per sq mm predominantly solitary; extremely small to very small, 0.1454-0.4484 mm; (ave. 0.3393 mm) in tangential diameter. Vessel elements extremely short, 0.4363-0.7635 mm (ave. 0.59-38 mm); perforation plates simple; tyloses sparse.

Parenchyma a po tracheal uniseriate· para tracheal

moderately few, (di ff use and in short

bands); occasionally (scanty to narrow

35

Fig. 8. Palosapis [A. thurif era (Blanco) Blume ssp. thurif era]

Fig. 9. Mindanao palosapis (A. costata Korth.)

vasicentric); strands mostly of 3-8 cells (ave. 5).

Rays few to moderately numerous, 4-6 per sq mm (ave. 4); of two kinds, uniseriate and multiscria te, the multiseriate heterocellular, 2-6 cells wide (mostly 4-15) with 1-4 rarely slightly more marginal rows of square or upright cells (sheath cells present); extremely fine, 0.0727-0.1333 mm wide (ave. 0.1091 mm); very low to low, 0.56

1.83 mm (ave. 1.094 mm); the uniseriate composed mostly of square

36

to upright cells, extremely fine 2-3 ..um (ave. 2) or 0.233 mm wide; extremely low to very low 0.13-0.53 mm (ave. 0.38 mm) or 4.17 rows of cells high (ave. 9 cells) or occasionally slightly more; ray vessel pits simple, rounded, ovoid to elongated.

Silica inclusions not observed.

Fibers medium-sized to moderately long, 1.0323 - 2.36 mm (ave. 1.755 mm); thin-walled (ave. 0.009 mm); lumen width. (0.012 mm); diameter (ave. 0.031 mm); non-septa tc.

Intercellular canal extremely small, 0.0606-0.1212 mm (ave. 0.0848 mm) in tangential diameter, about half as large as the vessels or typically smaller than this element.

3. A. thurifera (Blanco) Blume ssp. thurif era (palosapis) (Figs. 8, 11and14)

Vessels moderately few to moderately numerous, 6-17 (ave. 9) per sq mm almost exclusively solitary; extremely small, predominantly 0.1212 - 0.4364 mm (ave. 0.2424 mm) in tangential diameter.

Vessel elements extremely short, 0.5090 - 0.61 mm (ave. 0.4726 mm); perforation plates simple, slanting or horizontal; tyloses present.

Parenchyma typically vasicentric and diffuse. forming short lines from ray to ray; the vasicentric parenchyma inconspicuous; those associated with intercellular canals rather broad and in bands, predominantly 3-9 or slightly more cells wide; strands commonly of 3-5 or slightly more.

Rays moderately numerous to numerous, 5-7 per sq mm (ave. 5); of two kinds, uniseriate and multiseriate; the multiseria tcs heterocellular, 3-10

(mostly 8 cells wide); with 1-4 marginal rows of square to upright cells (sheath cells present), 0.083 mm wide; and very low to low (ave. 0.85 mm); the uniscriates composed mostly of square to upright cells, extremely f inc 0.018 .. 0.036 mm wide (ave. 0.02442 mm); and 7-17 cells high or occasionally slightly more; ray-vessel pits simple, rounded, oval to elongated.

Silica inclusions not observed.

Fibers medium-sized to very long, 0.93 - 2.39 mm (ave. 1. 76 mm), thin-walled (ave. 0.009 mm); lumen width (ave. 0.012 mm); diameter (ave. 0.031 mm); non-septate; with bordered pits.

Intercellular canals extremely small, 0.04848 - 0.09696 mm (ave. 0.0606 mm) in tangential diameter and typically smaller than the pores.

DISCUSSION

A. Taxonomy /Dendrology

• Bark and blaze characters of taxa

From experience botanists and laymen alike know that merely observing the characters of the leaves and flowers in the forest for identification is of limited value. This is because trees attain great height that it becomes hard to observe readily the leaves and flowers from the forest floor. The situation therefore calls for alternative or supplementary data which can be obtained quickly from the characters offered by the bark and blaze (slash) for more accurate tree identification in the field.

The specific bark type and characteristic manifestations in Philippine Anisoptera are summarized in Table 3. Based on color of the outer bark, A. aurea is distinguished from the

Fig. 10. Dagang (A. aurea Foxw.)

Fig. 11. Palosapis [A. thurif era (Blanco) Blume ssp. thurif era]

Fig. 12. Mindanao palosapis (A. costata Korth.)

Figs. 10-12. Tangential section showing rays mostly heterocellular multi­seriates with sheath cells and appears to be highest in A. costata Korth. and lowest in A. aurea Foxw. (80x).

37

Fig. 13. Dagang (A. aurea Foxw.)

Fig. 14. Palosapis [A. thurifera (Blanco) Blume ssp. thurif era]

Figs. 13-14. Radial section showing heterocellular multiseriate rays with marginal rows of square to upright cells (BOX).

Fig. 15. Mindanao palosapis (A. costata Korth.)

38

other members by its distinctly cream­brown bark. The suggestive bark type for the group based on previous works is the flaky-fissured type (de Rosayro 1953, Tamolang 1953, Whitmore 1963, 1968, Aragones 1985). During the earlier growth stage, the bark appears to be fissured and becomes flaky through time. This is due to the cracking of the outer bark tissue technically known as the phelloderm (Whitmore 1963, 1968, Aragones 1985). The cracked outer bark then becomes flakes, and in this particular group, peels away starting from below the bole. In A. aurea, however, the flakes are observed to be shaggily persistent, remaining at the bole for sometime as compared to the other members where the flakes easily peel off. The warty len ticella te characters of the bark surface is, likewise, typical for the group.

The blaze or slash made on the bark through the bole by a sharp bolo to expose the inner clements and striking features of the inner bark has been used by various authors for tree idcntif ica tion (de Rosayro 1953, Tamolang 1953, Whitmore 1963, 1968, Aragones 1985). In this particular group, A. thurif era ssp. thurif era and A. aurea exhibit yellowish-orange b_laze with bands of yellow and reddish to pinkish tissues. On the other hand, A. costata has cream-yellow blaze with bands of yellow and lighter tissues.

The resinous exudate or dammar yielded by members of the group has also proved to be diagnostic. In A. costata, pale grey smear slowly exudes from the cut portion, while the others yield clear-watery exudations.

• Vegetative and reproductive morphological characters

Based on leaf characters, the gen us appears to be homogeneous as member

species exhibit coriaceous, oblong to oblanceolatc to obovate shape of leaves. It was distinguished by Ashton (1982) from the other genera und~r the famil) Dipterocarpaceae by the distinct nerves of the leaves curving toward the margin and anastomosing to form distinct intramarginal nerves (Figs. 1-3).

However, species vary in the quality of indumcntum. It is easy to recognize A. aurea in the field through the golden brown tomentum on the lower leaf surface. A closer exa mina ti on of the lower leaf surface reveals a dense indumentum of unicellular headed pel ta te emargina te hairs imparting the characteristic color (Ashton 1964). A. costata has the largest epilose leaf among the Philippine species, measuring up to 18 x 11 mm with the nerves up to 22 pairs. Ashton ( 1982) noted this species to be the most variable under the genus with respect to leaf characters. The leaf may be epilose (as that observed in ZAMBOWOOD, Zamboanga Sur) or it may possess densely pilose hairs with relatively small and f cw-nerved leaves as in the specimen collected from Malaya.

The characteristics of the flowers and fruits are found to be a strong diagnostic basis in distinguishing the species (Ashton 1982). In terms of the number of stamens, A. costata never exceed 25, while in A. aurea and A. thurif era ssp. thurif era the minimum number is 30 (Ashton 1982). Individual differences and variations in fruit and characters, i.e., size of wings, shape and texture of fruiting calyx tube, also help in correct species id en tif ica tion.

• Taxonomic status

In his recent monograph of the family Dipterocarpaceac, Ashton (1982) circumscribed the genus Anisoptera

with a range of distribution from Chittagong and Iq.dochina to New Guinea and Malcsia . He divided the gen us in to two sections: Section Anisoptera cxhi bi ting lanccola te flower buds, and Section Glabrae with subglobose flower buds. The Philippine representatives belong to the first section.

There are now only three correct and validly recognized Philippine species based on Ashton's (1982) revision of the family as opposed to the four species listed by Salvosa (1963) and Merril (1923). A. brunnea Foxw. is reduced as a synonym of A. thurijera ssp. thurifera. Merrill's (1923) A. curtisii Dyer ex King is found not to occur in the Philippines (Ashton 1982). A. mindanensis, a species listed in Salvosa (1963), is considered a synonym of A. costata (Ashton 1982).

Of the three species under the genus, A. aurea is endemic to the Philippines, while A. costata is the most widely distributed species occurring in Burma, Thailand, Cambodia and Cochinchina. Those occurring in Malesia can also be found in Malaya, Sumatra, West Java (one record) and Borneo (S.B. Kalimantan, Sabah, Brunei and N.B. Sarawak).

A. thurif era previously considered by authors as a straight Philippine species (Salvosa 1963, Merril 1923) is now a goegraphical subspecies. It is distinguished from its New Guinean counterpart by the oblanceol'ate to lanceolatc and predominantly acuminate leaves and the 35-47 stamens. The New Guinean subspecies

* A natural floristic kingdom embracing the Malaysian Federation, Indonesia, Philippines and New Guinea.

39

A. thurijera ssp. polyandra has obovate leaves and 37-57 stamens (Ashton 1982).

B. Wood Anatomy

The important macroscopic and microscopic features of the three species of the palosapis group arc shown in Table 2. The gross f ea tu res with their common features in structure and physical characteristics are not enough to identify the wood of the individual Anisoptera species simply because they closely resemble each other. However, the wood color (heartwood when fresh is yellowish brown or straw brownish streaks or occasionally pink stripes), resinous odor of the wood when fresh, pores that arc readily visible to the naked eye and grain that is generally straight, sometimes crossed or wavy, possibly lead to the identification of the group but not exactly to the specific identity.

Generally, parenQhyma appear to be more of apotrachcal (diffuse), least dense per sq mm in A. costata and fairly abundant in A. aurea. Sometimes they also tend to be paratrachcal, forming to narrowly vasicentric to slightly aliform, apart from those associated with intercellular canals, stranded broadly at 4-8 cells in A. aurea, 3-8 in A. costata and 3-5 in A. thurif era ssp. thurif era. Vessels are predominantly solitary, occasionally in pairs, with diameter ranging from 0.0848 to 0.4484 mm. A. costata has the largest pores (ave. 0.2182 mm).

Another important ann to mi cal f ea turc of the group is the axial intcrccllular canal, an outstanding feature of the family Diptcrocarpaceae except in the genera Marquesia and Monates (Notcalf and Chalk 1950). Both genera, however, are not represented in the Philippines. The interccllular canals are diffuse, typically smaller than the pores or about half as large as the

40

vessels surrounded by parenchyma. They are scattered throughout the wood singly or in pairs and in short tangential series of 3-8 for all the three species. They are very few and appear · to be largest in A. costata (ave. 0.085 mm), followed by A. aurea (ave. 0.07 mm) and smallest in A. thurijera ssp. thurijera which is occasionally filled with whitish resin. These findings compare favorably with those of Reyes (1938), but it was not stated if his data came from the same group of wood samples or from a number of different samples of the same species.

The multiseriate rays observed in the three species commonly share the presence of sheath cells but this feature cannot point out distinct species differences. The multiseriate rays in number of cells wide can help to a certain extent in identifying them. For example, the multiseriates in A. thurif era ssp. thurij era ranges from 3 to l 0 cells wide (mostly 8), A. aurea (2-6 cells, mostly 5), and A. costata (2-7 cells, mostly 4-5). Again, the present descriptions and findings agree with Reyes' (Ibid) observations of the multiseriate rays in the three Anisoptera species based on the predominant number of cells. The height of the multiseria te rays is highest in A. costata (ave. 1.094 mm), followed in descending order by A. thurijera ssp. thurijera (ave. 0.85 mm) and A. aurea (ave. 0. 7 4 mm). Meanwhile, the uniseriate rays are also composed of square to upright cells, but sometimes with mixed procumbent cells. The rays are all classified as extremely fine for the three palosapis species: A. costata (ave. 0.242 mm), A. au re a (ave. 0.036 mm) and A. thurij era ssp. thurifera (ave. 0.0244 mm).

Some interesting facts were also noted in this study. Fiber mensuration

indicates that A. aurea gave the longest fibers with an average length of 1.78 mm, while the other two ha.d an identical average of 1.75 mm. Fiber diameter did not significantly vary among the species. On the other hand, cell-wall thickness was considered "thin" because the lumen was greater than the wall thickness. This is in accordance with the IA WA Standard terms for cell wall thickness of wood fibers.

CONCLUSION AND RECOMMENDATION

The Philippine Anisoptera proves to be a well- defined group under the family Dipterocarpaceae with one species (A. aurea) endemic to the country. The different species can be distinguished from each other using a combination of the bark and blaze characters, and also leaves, flowers and fruits.

Specific identification of the Philippine Anisoptera woods based on macro-anatomical structure is rather difficult. Many characteristics are common throughout the family as well as the genus. Microscopic features, on the other hand, show more differences although minute details such as pore sizes, multiseriate rays and f ibcr dimensions are not sufficient criteria for specific identification.

It is recommended that further collection of fertile her barium specimens and wood samples of A. costata be made in other places other than Zamboanga and Basilan provinces where it abounds. Records show that the species was first collected in Naga­naga, Zamboanga and later for this study, in lpil, Zamboanga del Sur.

41

LITERATURE CITED

ARAGONES, E.G., JR. 1985. The identification of some commercial and lcsscr­known timber trees in Mt. Makiling, Luzon, based on field characters of bark and blaze. MS Thesis. UPLB Graduate School, College, Laguna (Philippines).

ASHTON, P.S. 1982. Dipterocarpaceae. Flora Malesiana. Ser. 1, Vol. 9. 291-326.

1964. Manual of the Dipterocarp Trees of Brunei State. Oxford Univ. Press. 16-47.

BROWN, W.H. 1921. Philippine resins. Minor products of Philippine forests. Vol. 2. 52-54.

CLOVER, A.M. 1906. Philippine wood oils. Phil. J. Sci. a 1(1): 181-202.

ELLA, A.B. and A.L. TONGACAN. 1987. Tapping of palosapis. FPRDI J. 16(1 & 2): 15-16.

FOXWORTHY, F.W. 1938. Philippine Dipterocarpaceae III. Phil. J. Sci. 67: 241-333; 9 pits. 12: 1-289, 23 pits. 1 map.

MENIADO, J.A., F.N. T AMOLANG, F.R. LOPEZ, W.M. AMERICA and D.S. ALONZO. 1975. Wood identification handbook. Vol. I. 77-78.

MERRILL, E.D. 1923. An enumeration of Philippine flowering plants. Vol. 3, Bureau of Printing Media.

REYES, L.J. 1938. Philippine woods. Tech. Bull. 7, Dept. Agr. Comm., Manila.

ROJO, J.P. 1979. Updated enumeration of Philippine dipterocarps. Sylvatrop, Phil. For. Res. J. 4(3): 123-145.

SAL VOSA, F.M. 1963. Lexicon of Philippine trees. Bull. No. 1, FPRDI, College, Laguna, Philippines.

SYMINGTON, C.F. 1943. Foresters manual of dipterocarps. Malay For. Rec. No. 16, Singapore.

TAMOLANG, F.N., R.R. VALBUENA, J.A. MENIADO AND B.C. DE VELA. 1963. Standards and procedures for descriptions of dicotyledonous woods. Bull. No. 2, FPRDI, College, Laguna (Philippines).

THE PHILIPPINE RECOMMENDS FOR DIPTEROCARP PRODUCTION. 1985. PCARRD Tech. Bull. No. 58. 96p. PCARRD, Los Banos, Laguna (Philippines).

PROPERTIES OF GREEN AND YELLOW VARIETIES OF COCONUT (Cocos nucifera L.)

Zenita B. Espiloy, Marina A. Alipon, Mario M. Maruzzo and Mariluz SP. Dionglay 1

ABSTRACT

The natural variation in wood quality arising from differences in anatomical, chemical, mechanical and physical properties of green and yellow varieties of coconut was studied.

The yellow variety had higher values in terms of fibrovascular bundle frequency fiber length, cell wall thickness, relative density,· compressive and bending strengths, hardness. shear, toughness, amount of hot water extractives, hollocellulose and starch contents.

On the other hand, the green variety had higher values in terms of vessel length, vessel diameter, moisture content, shrinkage, ash content, alcohol-benzene extractives, 1% NaOH solubility, lignin, pentosans and silica content. ·

However, differences in the above properties were statistically insignificant between varieties except for the compressive and bending strengths and the shear and hardness tests on the tangential soft portions of the specimens. The green variety had higher shrinkage or more collapse than the yellow variety.

INTRODUCTION

Coconut is one of the cocoid palms, a major group classified in the anatomy of the individual genera of palms (Tomlinson 1961). It is mainly distributed in the tropical coastal regions of Asia, Oceania, Africa and Latin America. These regions have well-distributed rainfall, between 127-229 cm, and lie within la ti tu de 20° north and south of the equator.

Cultivated in most parts of the Philippines, the coconut thrives along the seashore and inland, up to altitudes of about 700 m, and in some regions up to 1,500 m (Brown 1918). The coco palm provides most of the basic

requirements of man ranging from food, shelter, medicine, wine, beverages, oil to other industrial and economic products. Hence, it is regarded as the "Tree of Life." The trunk is a po ten ti al source of raw materials for housing components, furniture, particleboard, short-span bridges, fence posts, electric power and comm uni ca ti on poles, novelty i terns, tool handles and other turned products.

Coconut plantations in the Philippines total about 3.3 million ha. In 1982, it was estimated that there were about 409 million coconut trees in the country, 345 million of which were

1 Researchers, :-lousing and Materials Division, FPRDI, DOST, College, Laguna 4031.

fruit-bearing. More than half (52.5%) of the total area planted to coconut are found in Mindanao. However, there is a slightly greater number of trees in Southern Luzon (91 million trees) than in Mindanao (90 million trees). A survey of four provinces in Luzon reveals that almost half of the coconut tree plantations is more than 50 years old and the bulk of senescent trees (61 %) is in Quezon province (Garcia 1988).

Until lately, the processing and utilization of old coco trunks were not given much attention. Not until it was surmised that their conversion into lumber for construction and other purposes could provide an economic way of disposing what might be considered a waste material. This prompted the FPRDI and later the Philippine Coconut Authority and other coconut producing countries in the Asia-Pacific region to investigate the properties and potential uses of coco wood (Rojo et al. 1988, Madrazo 1988, Punchihewa 1989, de Silva 1989).

Review of Literature

The coconut stem belongs to a type of anatomical structure which does not exhibit seasonal or annual growth layer and therefore differs entirely from the wood structure. Gross observation of the cross section reveals that the fibrovascular bundles are congested in the dermal zone and sea ttcred in the subdermal and central zones (Mcniado and Lopez 1976, Espiloy and Maruzzo 1986).

On the average, the dermal and a part of the su bdermal zones occupy the hard outer layer which is about 47% of the trunk's cross section. The soft portion (part of the subdermal zone and whole of the central zone) occupies about 53% of the trunk's cross section (de la Cruz

43

et al. 1975). The anatomical structure of coco wood has been studied hy Kaul (I 960), Richolson and Swarup (I 976), Parthasarthy and Kloot (1976) and Sudo (1978).

The density of coco wood increases from the top to the butt and from the central to the dermal zones. The moisture content of a freshly-felled coco tree differs considerably from butt to top and from the core to the outer portion. The MC of the core in the butt and top ends reaches up to 550% and 303% respectively. In the outer portion, the top end has a higher MC than the butt end; in the intermediate portion, however, there is a slight variation between these two parts (Mosteiro 1976, 1978, Laxamana and Tama yo 197 8 ).

The mechanical and physical properties of coco wood have been investigated by Kloot (1952), Sasondoncillo (1971), Walford and Orman (1976), Medrano and Lauricio (1977), Espiloy (1978) and Kininmonth (1979).

The inherent ability of coco timber to resist biological deterioration varies considerably within the cross section of the trunk and from butt to top. A test conducted by Mosteiro et al. (1976) on half-round, round and sawn coco timber under graveyard conditions showed that the soft portions, which had lower density, were completely destroyed by termites and fungi after 1 1/2 years. The denser outer portions were destroyed after 2 years and 5 months by the same organisms.

Sawn lumber with a large proportion of the soft portion was destroyed after 6 to 12 mon tbs. The hard portion of untreated mature coco timber when used in house construction and not in contact with the soil, may last beyond

44

10 years in service. This indicates that natural durability is greatly influenced by the prevailing conditions existing in the place of installation.

Research studies conducted by de la Cruz (1975), Bergsen (1976), Mosteiro (1978) and Jensen (1979) showed that it is feasible to saw coco trunks with the use of ordinary chainsaw, stcllite or carbide-tipped saw blades and standard high-speed steel blades. For circular sawing, the use of carbide-tipped saw gives satisfactory results compared to the ordinary high-speed steel saw.

At FPRDI, almost 15 years of coco stem research yielded invaluable results and ushered in knowledge on the di ff cren t end uses of coco wood such as: material in the manufacture of novelty products (Mosteiro 1980); furniture such as classroom chairs (Mosteiro 1983); roof shingles (Floresca 1989); plywood and blockboard (Tesoro 1984); particleboard (Pablo et al. 1977); wood cement boards (Pablo 1988); and grocery product pallets (Villa velez 1986).

Still there arc a few areas where b:Jsic research information on ~oconut

u tiliza ti on is wan ting or ad di tiona l data needed. Requirements for dimensional stability, strength, density, proximate chemical analysis, fiber morphology or combinations thereof can only be met if thorough information on coco wood properties is available. Hence, this study was conceived.

OBJECTIVES

1. Determine the different basic properties of green and yellow varieties of coconut, namely: relative density, moisture content, shrinkage, fibrovascular bundle frequency, fiber and vessel measurements compressive and bending strengths,

shear, toughness, proximate chemical analysis including starch and silica contents.

2. Evaluate the interrelationship of the chemical, physical and mechanical properties with the anatomical structures within and between varieties.

MATERIALS AND METHODS

Five mature trunks each of green and yellow varieties of coconut were collected from General Luna, Quezon Province. The trunks varied from 60 to 70 years old, 28 to 30 cm in a\ cragc diameter and 12 to 16 m in height. They were apportioned for anatomical, chemical, physical and mechanical properties.

The sampling scheme used is shown in Figure 1. Tests for anatomical and chemical properties represented three height levels (butt, middle and top). Only the butt and middle were tested for physical and mechanical properties, and tested at green condition. The methodology used in determining the different properties are as follows:

Anatomical Properties

Fibrovascular bundle frequency determination. Disks, 5 cm thick, were smoothened to get perfectly clean cross sections. The number of f ibrovascular bundles per unit area was determined directly from the cross-sectional disks 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 measurements. Matchstick-sized splints obtained from three radial portions were prepared and macerated in an equal volume of

60% glacial acetic acid and 30% hydrogen peroxide. Maceration was done in water bath and heated for about 1-2 hours or until the splints turned whitish and soft. The macerated samples were washed with running water until the splints were acid-free, and fin ally soaked in 50% ethyl alcohol. Prior to fiber and vessel measurements, the test tube was shaken to separate the different structural elements. Fifty de.terminations per sample were made using a binocular microscope. The length, width, lumen diameter and cell wall thickness of fibers as well as length and diameter of vessels were determined and evaluated.

Chemical Propertie~

Sample disks allocated for chemical ana.lyses were debarked manually, cleaned, chipped and air-dried.

PHYSICAL & MECHANICAL

RD/MC · relative density/moisture content SH · shrinkage CII · compression parallel to grain T · toughness SB · static bending S·TH · shear (tangential hard) S·TS · shear (tangential soft) S·R · shear (radial)

ANATOMICAL

D · dermal Sd · subdermal C · Central

45

Composite sampling of the five trees was done for the butt, middle and top. These samples were then ground in a Wiley mill, sieved to pass through the 40 mesh 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 in analyzing of chemical components were standard methods of the Technical Association of the Pulp and Paper Ind us try (T APPi), except those used for lignin analysis (modified method by Effland) and silica (sulfuric acid method by Nicolas).

Physico-Mechanical Properties

The testing methods for the physical and mechanical properties were

SB

T

Cit

SH

RD/Mc

A

B

H·TH • hardness (tangential hard) H·TS · hardness (tangential soft) H·R · hardness (radial) H·E · hardness (end)

Cl

H-R

H-TH

S-R

s-rs

S-TH

Cl · compression perpendicular to grain

Fig. I. Sampling scheme used in the study.

46

-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

All data on different properties of green and yellow varieties of coconut were analyzed statistically using the Complete Randomized Design with subsampling.

RES UL TS AND DISCUSSION

The anatomical properties of green and yellow varieties of coconut are shown in Table I. These properties were determined axially (butt, middle and top) and radially (dermal, subdermal and central zones) which included frequency of fibrovascular bundles and characteristics of fibers and vessel elements.

The yellow variety had higher average values for fibrovascular bundle frequency than the green variety. But the respective values of both significantly increased from the butt towards the top and likewise, from the central zone towards the dermal zone.

Based on the grand means of fiber and vessel characteristics, the yellow variety had longer fibers with thicker cell walls. On the other hand, the green variety had longer vessels with wider diameters.

Table 2 shows the summary of ANOVA on the anatomical proP,.crties of coconut. A high degree of significance was observed in all ana to mi cal properties between height levels and radial portions, while variations between varieties and trees were found insignificant except for vessel diameter.

The proximate chemical composition of coconut is shown in Table 3. Based on the grand means for both varieties, the green variety had higher values in terms of percentages in ash content, alcohol-benzene extractives, I% caustic soda solubility, lignin, pentosans and silica contents. The yellow variety, in contrast, had higher hot-water extractives, holoccllulose, and starch contents. Variations in all chemical components, howevc r, were found insignificant between varieties but highly significant between height levels (Table 4).

The mean values for physical and mechanical properties of the two coconut varieties are shown in Table 5. In terms of relative density, compressive and bending strengths, hardness, shear and toughness, the yellow variety had higher values than the green variety.

Relative density is regarded as a function of the ratio of cell wall volume to cell void volume. As such, it is affected by cell wall thickness, structure, cell width, the relative proportions of different types of cells and the kind and amount of extractives present (Elliott 1966). Moreover, relative density is a measure of the strength properties of a material (Floresca et al. 1973). It is interesting that the yellow variety, having higher relative density values than the green variety, had more fibrovascular bundles per unit area, longer fibers with thick cell walls, more hot-water extractives and more cellulose and starch contents.

The green variety, however, had higher MC because its long and wide fiber could hold more water. This accounts for the same level of significance in vessel diameter (Table 2) and moisture content (Table 6) between varieties.

Table 1. Mean values for anatomical properties of green and yellow varieties of coconut <C:ocosnucij'era L.)

VARIETY HEIGHT RADIAL FIBROVASCULAR FIBER CHARACTERISTIC (nm) VESSEL CHARACTERISTIC (nm) LEVEL PORTION BUNDLE FREQUENCY Fiber Fiber Lumen Cell Wall Vessel Vessel

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

Yellow Variety Butt Dermal 1.189 1. 73 0.035 0.011 0.012 1.43 0.21 Subdermal 0.515 2.10 0.037 0.009 0.014 2.31 0.25 Central 0.262 2.03 0.037 0.012 0.013 2.74 0.23 Mean 0.655 1.95 0.036 0.011 0.013 2.16 0.23

Middle Dermal 1.569 1.97 0.034 0.013 0.011 2.15 0.23 Subdermal o.S83 2.24 0.037 0.016 0.010 2.87 0.27 Central o.3n 1.86 0.034 0.015 o.orn 3.14 0.25 Mean 0.943 2.02 0.035 0.015 0.010 2.72 0.25

Top Dermal 2.716 1.01 0.030 0.017 0.007 0.68 0.16 Subdermal 1.828 1.31 0.030 0.017 0.006 0.97 0.22 Central 1.013 1.24 0.031 0.018 0.007 1.14 0.22 Mean 1.852 1.19 0.030 0.017 0.007 0.93 0.20

Green Variety Butt Dermal 1.028 1.82 0.037 0.013 0.012 2.02 0.25 Subdermal 0.486 2.06 0.038 0.013 0.012 2.69 0.29 Central 0.253 1.99 0.036 0.014 0.011 2.92 0.28 Mean 0.589 1.96 0.037 0.013 0.012 2.54 0.27

Middle Dermal 1.343 1.86 0.035 0.015 0.010 2.20 0.23 Subdermal 0.909 2.14 0.036 0.020 0.008 2.93 0.30 Central 0.526 1.95 0.035 0.019 0.008 3.09 0.28 Hean 0.926 1.98 0.035 0.018 0.009 2.74 0.27

Top Dermal 2.493 0.83 0.029 0.016 0.007 0.62 0.17 Subdermal 1.569 1.14 0.031 0.018 0.006 0.78 0.21 Central 1.061 0.93 0.031 0.019 0.006 0.95 0.22 Mean 1.708 0.97 0.030 0.018 0.006 0.78 0.20

Grand Mean Yellow 1.15 1. 72 0.034 0.014 0.010 1.94 0.23 Green 1.07 1.64 0.034 0.016 0.009 2.02 0.25

Table 2o ANOVA result of the anatomical properties of green and yellow varieties of coconut <(;oco~11uci.fera L.)

SOURCE OF VARIATION

Variety (green and yellow)

Tree (5)

Height level (butt, middle, top)

Radial portion (dermal, subdermal, central )

ns ·· Not significant * . Significant at 95% level

** . Significant at 99% level

Fibrovascular Bundle Frequency

0.25 ns

0.44 ns

3.20**

63.91**

of probability of probability

F -V A L U E

F i b e r

Fiber Length

0.84 ns

0.22 ns

17.61**

4.16**

A N D S T A T I S T I C A L S I G N I F I C A N C E V~ssel Characteristic C h a r a c e r i s t i c

Fiber Diameter Lumen Width Cell wall Vessel Length Vessel thickness Diameter

0.12 ns 1.41 ns 1.04 ns 0.39 ns 6.14*

1.00 ns 1.97 ns 0.60 ns 0.13 ns 0.39 ns

** 18.38** 6.70** 23.39** 10.57 3.66**

2.91** 6.86** 5.32** 16.11** 10.22**

Table 3. Mean values for proximnte chemical composition of green and yellow varieties of coconut tCoco.\'nucifera L.)

c H E M I c A L c 0 H p 0 N E N T (%) 1

VARIETY HEIGHT Solubilities in: LEVEL Ash Alcohol- Hot- 1% NaOH Lignin Holocellulose Pentosans Silica Starch

benzene wnter

Yellow variety Butt 1. 7179' 2.0019 4.9683 19.5498 27.9001 63.4119 19.7208 0. 1225 0.9471

Middle 1.6076 1.8328 3.5174 19.0266 23.9428 69.0994 20.5985 0.1338 1.0742

Top 2.0914 3.0673 4.5504 25.6803 24.3381 65.9527 22.7297 0.0560 8. 7372

Green variety Butt 2. 1820 2.6806 4.8148 22.4133 27.3557 62.9670 20.6430 0.1228 1.1955

Middle 2.1265 2.3075 5.2714 20. 1423 24.6422 65.6524 20.3814 0.2445 1.2671

Top 1.9368 3.7076 2.3814 24.3582 25.7412 66.2330 22.8919 0.1355 2.5720

Grand Mean Yellow 1.8056 2.3307 4.3454 21.4189 25.3937 66.1547 21.0163 0. 1041 3.5862

Green 2.0818 2.8986 4.1559 22.3046 25.9130 64.9508 21.3054 0.1676 1 .6782

1 Based on moisture-free weight of sample.

Table 4. Sunmary of ANOVA on the proximate chemical composition of green and yellow varieties of coconut CC:ocosnucij'era L.)

SOURCE OF

VARIATION

Variety (green, yellow)

Height level (butt, middle, top)

F·VALUE A N D S T A T I S T I C A L ALCOHOL· HOT-WATER 1% NAOH LIGNIN

ASH BENZENE SOL. SOL. SOL.

2.83ns 1.10ns 0.04ns 0.13ns 0.12ns

79.-60** 12.75** 38.54** 453.49** 93.41**

ns · Not significant ** · Significant at 99% level of probability

S I G N I F C A N C E HOLOCELLULOSE PENTOSANS SILICA STARCH

0.39ns 0.06ns 1.94ns 0.53ns

** 93.96 ** ** ** 49.80 161.25 245.98

Table 5. Mean values for physical and mechanical properties of green and yellow varieties of coconut <Cocos nucif era L. >

P R 0 P E R T Y MOISTURE YELLOW VARIETY GREEN VARIETY CONDITION BUTT MIDDLE AVE. BUTT MIDDLE AVE.

(1) (2) (3) (4) (5) (6) (7) (8)

1) Moisture Content1C%) Green 146.56 165.75 156.16 233.19 224.49 228.84 2) Relative Density Green 0.439 0.392 0.415 0.372 0.335 0.353 3) Shrinkage (%) Green to oven-dry

a) Tangential 5.91 11.46 8.69 11. 76 14.16 12.96 b) Radial 6.09 12.80 9.45 12.76 14.92 13.84

4) Static Bending Green a) Modulus of rupture (MPa) 40.52 26.66 33.59 29.72 21.08 25.40 b) Stress at elastic limit CMPa) 29.36 16.90 23.13 19.81 14.04 16.92 c) Modulus of elasticity ex 1000 MPa) 5.49 3.99 4.74 3.83 2.68 3.26

5) Compression Parallel to Grain (MPa) Green a) Maximum crushing strength 21.66 15.98 18.82 16.64 11.30 13.97

6) Compression Perpendicular to Grain Green CMPa)

a) Stress at elastic limit 8.05 2.95 5.50 4.46 2.56 3.51 7) Hardness CkN) Green

a) Tangential hard a.n 4.27 6.52 6.24 4.53 5.39 b) Tangential soft 3.31 1.25 2.28 1.83 1.20 1.51 c) Radial 6.99 2.84 4.91 4.24 2.75 3.50 d) End 6.27 2.44 4.36 3.98 2.62 3.30

8) Shear Parallel to Grain CMPa) Green a) Tangential hard 8.06 5.03 6.54 6.76 4.53 5.65 b) Tangential soft 6.87 4.00 5.43 5.03 3.55 4.29 c) Radial 6.33 3.72 5.02 5.39 3.34 4.37

9) Toughness (Joule) Green a) Tangential 28.79 22.50 25.64 26.35 19.66 23.01 b) Radial 28.63 23.41 26.02 25.79 19.98 22.88

Based on volume at test and weight when ovendry.

Table 6. Sunmary of ANOVA on the physical and some mechanical properties of green and yellow varieties of coconut <Cocos nucif era L. )

F - V A L U E A N D S T A T I S T I C A L S I G N I F C A N C E

P H Y S I C A L P R 0 P E R T Y SOURCE OF VARIATION

P R 0 P E R T Y SHRINKAGE

Relative Moisture Radial Tangential

M E C H A N I C A L STATIC BENDING

M 0 R FSEL M 0 E

CRUSHING STRENGTH PARALLEL TO GRAIN

TOUGHNESS Radial Tangential

density content

Variety (green, 3.SOns 8.59* 3.84ns 4.53ns 7.46 6.35* 11.83** 5.67* 2.31ns 1.97ns yellow)

Tree (5) 2.13ns 4.25* 1.03ns 1.08ns 0.42ns 0.40ns 0.39ns 0.84ns 0.74ns 0.65ns

Height level 0.15ns 0.10ns 0.93ns 0.80ns 0.31ns 0.53ns 0.40ns 0.25ns 0.19ns 0.18ns (butt, middle)

Radial portion 12.38* 13.34** 7.80** 9.99** 12.93** 12.65** 14.86** 11.38** 12.44** 12.11** (hard, soft)

NS · Not significant * - Significant at 95% level of probability

** - Significant at 99% level of probability

In the conduct of the shrinkage test for both varieties, dimensional changes from green to oven-dry condition sometimes resulted in collaP,se which generally appeared as merely excessive shrinkage and was frequently so interpreted. Collapse was observed in specimens obtained near the core, particularly those in the upper (middle to top) portion of the coconut trunk (Figs. 2a, b). The cell walls in the core portion were thinner than those outside. Moreover, MC was higher at the core than near the peripheral portion of the trunk. The green variety was observed to have more collapse than the yellow variety (Fig. 2b) apparently because of lesser cellulose content and higher pentosan content· in the former. Moreover, its fibers were shorter and had wider lumen and thinner cell walls.

53

The summaries of ANOVA on physical and mechanical properties of coconut are in Tables 6 and 7. There were significant differences in all physical properties and some mechanical properties such as static bending, crushing strength parallel to grain and toughness between radial portions. However, the differences · were insignificant between height levels.

Differences in moisture content, static bending and crushing strength parallel to grain were significant between varieties (Table 6). A high level of significance was observed in shear, hardness and compression perpendicular to grain between height levels (Table 7). Likewise, there was a significant difference in compression perpendicular to grain as well as shear and hardness tests on the tangential soft portions between varieties. The orientation of specimens in the

Fig. 2a. Shrinkage specimens showing collapse near the core in the middle portion of the yellow coconut trunk.

Table 7. Sunmary of ANOVA on some mechanical properties of green and yellow varieties of coconut CCocosnuci.feraL.) tested at different portions of the specimens

F · V A L U E A N D S T A T I S T I C A L s I G N I F I C A N C E

SOURCE OF s H E A R H A R D N E s s COMPRESSION VARIATION Tangential Tangential Radial Tangential Tangential Radial end PERPENDICULAR

Hard Soft Hard Soft TO GRAIN (FSEL)

* * Variety (green, 1.61 ns 6.55 3.39ns 0.97ns 8.62* 4.54ns 3.89ns 7.15 yellow)

Tree (5) 0.61ns 0.35ns 0.21ns 0.91ns 0.26ns 0.38ns 0.30ns 0.32ns

** ** ** ** ** ** ** ** Height level (butt, 9.11 7.46 10. 79 19.22 6.51 12.82 10.06 7.21 (middle)

ns - Not significant

* - Significant at 95% level of probability

** - Significant at 99% level of probability

• ii. - .

SS

Fig. 2b. Shrinkage specimens showing collapse particularly at the core portion of the green coconut trunk.

application of loading in the shear and hardness tests (Figs. 3 and 4) was influenced by the distribution of f ibrovascular bundles, i.e., more in the hard portion. Moreover, the cell walls in the soft portion were thinner than in the hard portion.

CONCLUSIONS

• The yellow variety has higher values in terms of fibrovascular bundle frequency, fiber length, cell wall thickness, relative density, compressive and bending strengths, hardness, shear, toughness, amount of hot-water extractives, holocellulosc and starch contents.

• The green variety has higher values in terms of vessel length, vessel diameter, moisture content, shrinkage, ash content, alcohol-

benzene extractives, 1 % caustic soda solubility, lignin, pentosans and silica con ten ts as compared to the yellow variety.

• Differences in the above properties are insignificant between varieties, except for the compressive and bending strengths as well as the shear and hardness tests on the tangential soft portions of the specimens.

• The results can be used as a basis for that popular notion among rural folks that the yellow variety is preferable to the green variety.

On the whole, the palm stem contains hard fibrovascular bundles scattered in softer parenchymatous ground tissues which are concentrated more in the peripheral than in the central region of the trunk's transverse section. The

56

TANGENTIAL HARD

TANGENTIAL SOFT

RADIAL

Fig. 3. Orientation of coconut wood portion in the application of loading in shear test.

END SURFACE

TANGENTIAL HARD SURFACE

TANG·ENTIAL SOFT SURFACE

RADIAL SURFACE

Fig. 4. Orientation of coconut wood portion in the application of loading in hardness

test.

57

peripheral portion of the palm stem, therefore, may have considerable value as a building material. The low natural durability of coco wood, which

makes it prone to bio-deterioration.1can be overcome by proper application of a suitable, economical and en v ironmen tally-safe preservative.

LITERATURE CITED

BROWN, W.H. and E.D. Merrill. 1918. Philippine palms and palm products. In Minor Products of Philippine Forests. Bull. No. 15. Bureau of Printing, Manila. 184-192.

DELA CRUZ, R.Z., D.V. SIBAYAN and A.S. DECENA. trunks into lumber. Technical Note No. 156. Laguna 4031.

1975. Sawing of coconut FPRDI Library, College,

DE SILVA, S. 1989. Coconut wood: a bibliography. A.P.C.C. Publication. FPRDI Library, College, Laguna 403 I.

ELLIOTT, G.K. 1966. Wood density in conifer. Tech. Comm. No. 8 Common. For. Bot., Oxford, England.

ESPILOY, E.B., JR. 1978. Coconut trunks for power and telecommunication poles. FORPRIDE Digest 7 (1). FPRDI Library, College, Laguna.

ESPILOY, Z.B. and M.M. ¥ARUZZO. 1986. Variability of frequency of fibrovascular bundles in some Philippine palms. The Phil. Lumberman 32(5): 26-31.

FLORESCA, A.R., J.E. ROCAFOR T and J.0. SIOPONGCO. 1973. Shrinkage of 182 species of Philippine woods. The Phil. Lumberman 9(4): 28-38.

, F.R. SIRIBAN and A.P. GESMUNDO. 1989. Design and _______ , development of coconut palm roof shingles. CORD 5(1): 63-92.

GARCIA, C.C. 1988. Availability and distribution of coconut palm stems in the Philippines. Annual Report. Palmwood Utilization (Asia). FPRDI Library, College, Laguna

JENSEN, P. 1979. Recovery in sawn timber from Cocos nucifera logs. In Proc. Coconut Wood - 1979 Seminar. Manila and Zamboanga, Philippines

KAUL, K.N. 1960. Anatomy of plants. Palm - I. Bulletin No. 51, National Botanic Gardens. Lucknow, India.

KININMONTH, J.A. 1979. Some physical properties of coconut wood. In Proc. Coconut Wood - 1979 Seminar. Manila and Zamboanga, Philippines.

KLOOT, N.H. 1952. Mechanical and physical properties of coconut palm. Austr. J. of Appl. Sci. 3( 4): 293-323.

58

LAXAMANA, M.G. and G.Y. TAMAYO, JR. 1978. Drying characteristics of coconut lumber. NSDB Technol. J. 3(3): 48-55.

MADRAZO, R.M. 1988. An overview of the research developments of the Philippine Coconut Authority - Zamboanga Research Cen~er. ~a~er presented during the training program of the Coconut Extension Trammg Center, Bago-Oshiro, Davao City, 10 March 1988.

MEDRANO, R.N. and F.M LAURICIO. 1977. Specific gravity and shrinkage of coconut palm timber (Cocos nucifera L.) in the Philippines. Unpubl. report. FPRDI Library, College, Laguna 4031.

MENIADO, J.A. and F.R. LOPEZ. 1976. Stem anatomy of <.:oconut (Cocos nucifera L.) FORPRIDE Digest 5(1): 60-61.

MOSTEIRO, A.P. et al. 1976. The preservative treatment of coconut (Cocos nucjf era L.) palm timber for electric power and communication poles. NSDB Technol. J. 1(1): 45-52.

1978. Treatability of coconut palm timber at different radial distances from center and height levels. A research problem submitted in partial fulfillment for an MS degree at UPLBCF, College, Laguna 4031.

1980. The properties, uses and maintenance of coconut palm timber as a building material. FORPRIDE Digest 9 (3&4): 46-53.

. 1983. Utilization of coconut lumber for furniture manufacture -------(classroom chairs). FPRDI J. 12 (1&2): 22-31.

PABLO, A.A. 1988. Production of cement-bonded panels from coconut wood and husk. Annual Report. Palmwood Utilization (Asia). FPRDI Library, College, Laguna 4031.

, J.B. SEGUERRA, JR., F.N. TAMOLANG and A.B. ELLA. 1977. -----Particleboard from wood species and aggic fibrous waste materials: coconut trunk and wood particle mixtures. NSDB Technol. J. 2(2): 34-43.

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PUCHIHEWA, P.G. 1989. Two decades of service to the coconut industry. A.P.C.C. Report. FPRDI Library, College, Laguna 4031.

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59

SJ\SON DON CILLO, R.S. 1971. Mechanical propercties of coconut palm (Cocos nucif era L.) from Los Banos, Laguna. Unpublished report. FPRDI Library, College, Laguna 4031.

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TOMLINSON, P.B. 1961. Anatomy of the monocotyledons II. Palmae. Oxford University Press. Amen House, London E.C.4.

VILLA VELEZ, L.V. 1986. Performance evaluation of grocery product pallets from coconut lumber. FPRDI J. 15{1&2): 26·42.

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PHYSICAL AND MECHANICAL PROPERTIES OF BAGRAS (Eucalyptus deglupta Blume) FROl\1 THE PAPER INDUSTRIES CORPORATION OF THE PHILIPPINES (PICOP)

Marina A. Alipon and Apolonia R. Floresca 1

ABSTRACT

Ten poles of 8- and 12-year old bagras (Eucalyptus deglupta Blume) trees were tested and evaluated for physical and mechanical properties using the American Standard for Testing Small Clear Specimens of Timber ( p-143 ).

Three bolts, 3 m long, were taken from each pole to represent the butt. middle and top. A 0.15 m-thick disk was cut from each bolt and sawn into 25 mm boards where samples for physical properties testing were taken. The remaining 2.85 m-long bolts were processed into /!itches 64 mm thick and fabricated for mechanical properties testing.

No significant di/ ferences existed between the physical and mechanical properties of 8-and 12- year old bagras trees. While di/ f erences in modulus of rupture, hardness (end), shear (tangential) and cleavage (radial) were apparent, these were rather small.

Evaluation of physical and mechanical properties indicates that bagras falls under moderately low strength (C4) at ages 8 and 12 years.

INTRODUCTION

Bagras (Eucalyptus deglupta Blume) is one of the more popularly known hardwoods in the Philippines. It has a straight, regular bole often reaching a height of 20-30 m and a diameter of 200 cm.

The tree is known in Agusan province as banikag and magoya'Ilgit; in Cotabato as bagras and bagaras; and in Zamboanga as amamanit and dinglas.

It is grown extensively in plantation by the Paper Industries Corporation of the Philippines (PICOP) in Surigao del Sur. The wood is good for pulp and paper making due to its thin-walled and medium-sized fibers (l\1cniado 1978).

The only a vaila blc data on bagras strength and re la tcd properties have been obtained by the Surigao Wood

1 Researchers, Housing and Materials Division, FPRDI, DOST, College, Laguna, 4031.

Preserving Company from samples trea tccl with Chroma tcd Copper Arsenate. Strength values based on green condition arc as follows (Tamolang and Rocafort 1986):

Relative density

Static bending

Stress at proportional limit (MPa)

Modulus of rupture (MPa)

Modulus of elasticity (GPa)

Compression parallel to grain

Maximum crushing strength (MPa}

Compression perpendicular to grain

Stress at proportional limit (MPa)

Shear parallel to grain

Maximum shearing strength (MPa)

Hardness

Side (kN}

End (kN)

Toughness (J/specimen)

0.36

26.4

42.7

6.20

20.9

1.87

4.74

1.65

2.44

15.70

These results, however, are inconclusive because of inadequate number of specimens used in the study.

To explore further the species' potentials for pole utilization, the Manila Electric Company (MERALCO) provided the Forest Products Research and Development J.nstitute (FPRDI) five trees each of 8- and 12 year-old bagras for the physical and strength tests.

Objectives

1. Determine the physical and mechanical properties of 8- and 12 year-old bagras at different height levels (butt, middle and top).

2. Determine the effect of tree age on the physical and mechanical properties of bagras.

61

MATERIALS AND METHODS

The test materials consisted of 10 poles of bagras, viz., five each of the 8- and 12-year old trees. Each pole measured 12 m long.

Three bolts, 3 m long, were taken from each pole to represent the butt, middle and top. A one-meter interval after each bolt was cut and discarded. A 0.15 m (6-inch) long disk was cut from the lower portion of each bolt and sawn in to 25 mm (I-inch) thick boards. Boards from pith to bark were sampled for observation of physical properties (viz., relative density and shrinkage).

The remaining bolts (2.85 m long) at each height level were processed into flitches 64 mm (2.5 inches) thick. Only one flitch per height level was taken and processed into specimens for mechanical properties determination (viz., static bending, compression parallel-to-grain, maximum shearing strength, hardness, toughness and cleavage). This was in accordance with the sampling procedure of Lauricio and dela Cruz (1969). Figure I shows the sampling scheme used in the study.

All tests followed closely the standard procedure of the American Society for Testin::' and Ma tcrials Designation: Method for Testing Small Clear Specimens of Timber (ASTM 1972). All specimens were tested at green condition.

Statistical Analysis

The data were statistically analyzed using Completely Randomized Design with Subsampling. Two sets of analyses were done using the following ma thema ti cal models:

Yijk = u +Ai+ Tj + Hk + Eijk (for between ages}

Yjk u + Tj + Hk + THjk + Ejk (for per age of

the trees}

62

3m Middle

12 m

lli 15m 2. 85 m

3m

.t5m

Physical properties (Relative density a Shrinka e)

2.85m

Mechanica I properties

Fig. 1. Sampling scheme used in the study.

RESULTS AND DISCUSSION

Tables 1 and 2 present the mean values of each tree per age and mean values of all trees per age at different height levels, respceti vely, in terms of physical and mechanical properties.

The mean relative density and tangential shrinkage were higher in the 8 year old bagras than in the 12 year old trees. Numerous 1i tera tu re on wood quality evaluation of different species within trees and among trees report a positive relationship between most wood properties and age of the trees. The deviations of the results from the relationship could be attributed to random variation between trees. It is interesting that some 8-year old trees exhibited higher values than the 12-ycar old ones.

Patterns of variations on the physical and mechanical properties along the height are shown in Figures 2 and 3. At 8 years old, the relative density increased from butt to middle and slightly decreased toward the top; at 12 years it increased from butt to top. Both tangential and radial shrinkage decreased from butt to top in the 8-year olds. At 12 years tangential shrinkage followed a trend similar to that of the 8-year olds; radial shrinkage slightly decreased from butt to middle and increased toward the top.

In terms of strength properties, a different trend was observed in the 8 year olds. There was an increase from butt to middle and a slight decrease tow a rd the top in C 11; a decrease from butt to top in modulus of elasticity (MOE), toughness and cleavage; a decrease from butt to middle and a

~ 2 0 ll.

e rn e Q ~ :! Cll ....

:g E·~d ~ ~ a; ~- ~- I ~ ll.•M-ll.~ - IO ::s :a;~ ::c: ·; C:::3 rzlll. =b c:::3 ~ c: .2'-" 'O e,, .... rn o Cll

0 .... c: Cll Cl !.S Ill I

Ill ~"I: .... :: Cll s.. IO -§~ ::s .a 0 ..c: -~ ll. ... '3 .... ll. .... ~ 8 ~ 'ti""" 0 0 c: ~ 0 0 "'::3 ~..:ci&:e ·c

~ ~- ..c: 0 .... rn

26 9.0 55 10.0 0.440·

25 8.0 45 8.0 0.430

24 7.0 35 6.0 0.420

23 6.0 25 4.0 0.410

Legend:

a - Hardness (E)

b -MOR (SB)

c-CL

d -Shear

e -Cleavage

f -SH (T)

g -cu h -Hardness (S)

i -MOE (SB)

j - RD

k -Cleavage

1 - Toughness

m -FSPL (SB)

n -SH (R) a

b c

d

e

f

g

h

k

m

n

BUTT MID TOP

HEIGHT LEVEL

c: 7 ·a ... z ll. e,, ~ 6 .£ I s:: c: 'ti ·a Cll 'il c: 8 :; rzl

... e,, ·o ... ..:ci .3

Cll 1 IO ll. ll.- Cll Ill

'ti al ........ C: IO §, !:?. ........ 0 ll. :; e ·: ::3 Ill

Ill ... Ill

f Ill IO Cll : I Cll ll. c: ll. c: 'fo So 1 ~ ~

Cll ::s o- Cll

0 ::c: ..c: 0 5 rn f-4

2.80 2.60 6.5 24 35

2~10 . 2.40 6.0 23 30

2.60 2.20 5.5 22 25

2.50 2.00 5.0 21 20

Fig 2. Pattern of variation on the physical and mechanical properties of 8-year old bagras along the height.

63

64

d ·;a @' '3' ...

t.'.l 0 0..

.3 6 tr.l

e ] ~ Ql ...

] ~ ~ ···"e ~ ~ed ...... (;!

~- 0. <ll ~~ I o.. ......... - .s ;:s gj-p.. :I: d .s ~o.. ;:~§~e 0 0.. 'Or.;> ·~ ~ 0 ·~ d Ql

~~ m~"t:· .... bO ~ I ;:s ..0 0 ..c:: (;!

0. 30 :g~g.-o~ Eo "O~ 0 o(j &: i:o ·;:: 0 .......... ~ .......... ~ .......... ~ 0

2i' ~

~ d Ql

0 Ql

~ (;!

Qi P::

28 9.0 70 10.0 0.460

26 8.0 55 8.0 0.430

24 7.0 40 6.0 0.400

22 6.0 25 4.0 0.370

Legend:

a - Toughness

b- CL c - RD

d- Hardness

(End)

e - Shear

f - Cleavage (J)

g - MOR (SB)

h - Cll

i - MOR (SB)

j - Cleavage (R)

k - SH

1 - Hardness

(Side)

m - I<'SPL (SB)

n - SH

a b

c

d

e

g

h

k

m

n

BUTT MID TOP

HEIGHT LEVEL

~

z 0.. .lo<: 6

d '? "O Ql

] d ·a E ;; r:i::l 0 ·o

Ql 8 ~7 o(j .3 g. 11.p.. Ql

] - E d~

"O :::, ~ o .......... e e "' -~ c:

"' "' Ql (;! Ql

~ ·a "' 0.. d bO Ql ..c:: (;!

~~ d ... bO > 'E (;! ;:s .s 0 .3 r:I

Ql 0 Ql

0 :I: ..c::

~ 5 tr.l

3.0 2.75 6.6 24.5 35

2.85 2.50 6.4 24.0 30

2.70 2.25 6.2 23.5 25

2.55 2.00 6.0 23 20

Fig 3. Pattern of variation on the physical and mechanical properties of 12-year old bagras along the height.

slight increase toward the top in modulus of rupture (MOR) (SB) and stress at proportional limit (Cl). The 12-ycar olds showed a consistent increase from butt to top except in cleavage (ta ngcn tia l) and toughness where it slightly decreased from butt to middle and increased toward the top.

It is surprising that bagras exhibited a different pattern along the height for both 8- and 12-year old trees. This could be explained by the ANOV A results in Tables 3 to 6. Note that the biggest source of variation was the trees.

To further determine variations between and within trees at a particular age, a separate analysis was conducted on the 8- and 12-year old trees (Table 5). Results showed a wider variation between trees at 8 years than at 12 years.

Table 3 shows the ANOV A between age of the trees. The effect of age was significant only for MOR, hardness (end), shear (tangential), and cleavage (radial), with the total variance contribution (Table 3) amounting to 5.18%, 3.76%, 22.11% and 15.40% respectively.

Variations among trees at 8 years were accounted by 47.59%, 76.54%, 83.98%, 76.64%, 83.70%, 77.58% 71.31%, 67.73%, 54.37%, 52.09% and 51.82% in relative density, MOR, fiber stress at proportional limit, MOE, compression parallel to grain, compression perpendicular to grain, hardness, side and end, cleavage, tangential and radial and shear (radial) respectively. The effect, however, of trees at 12 years was generally insignificant "!xcept in relative density, shrinkage, MOR, compression parallel to grain (Cll) and compression perpendicular to grain (cl) and shear (tangential).

65

The large variation between trees may be attributed to one or a combination of factors like the presence of tension wood, genetic diversity, differences in location or elevation, silvicultural treatment and other growth conditions. Variation in wood properties of trees grown in the same site is usually interpreted as an indication of genetic diversity (Alonzo 1977, Lantican 1975). Genetic diversity causes individual trees to react differently to existing environmental conditions. Thus, even among trees of the same age considerable variation in wood properties exists. On the other hand, the presence of tension wood in some trees at a certain height level can generally increase the physical properties and also lower some strength properties which in turn may affect the mean tree values. The other factors mentioned are reported to have influenced variatio!ls in wood properties between or among trees.

Height achieved significance only ii .. relative density, shrinkage (tangential), compression parallel to grain, hardness (end) and cleavage (tangential), accounting for only 21.03%, 22.19%, 17.09%, 20.680/o and 32.10% respectively of the total variation (Tables 3 and 4).

The effect of height on physical and mechanical properties was insignificant on 8 year old trees. But it was significant on 12-year old trees in terms of relative density, shrinkage (T), MOR and compression parallel to grain with total variance components of 52.41 %, 45.84%, 58.95% and 54.60% respectively.

The high percentage of total variance with respect to height in these properties was difficult to interpret because of expected parallel effect on

Table 1. Mean values of physical and mechanical properties of bagras <.Eucalyptus deg/upta- Blume)

PHYSICAL PROPERTIES MECHANICAL PROPERTIES TREE NO. AGE Relative Shrinkage Static Bending Compression Hardness Toughness Shear Cleavage

Dens Hy T R MOR FSPL MOE 11 to Grain 1 to Grain Side End T R (1) (2) (3) (4) (5) (6) (7) (8) MCS FSPL (12) (13) (14) ( 15) (16) ( 17)

(9) ( 10)

8 0.359 7.00 4.38 42.06 24.05 5.92 19.45 2.32 1.96 2.03 17.31 5.36 26.69 23.32 12 0.423 6.75 4.39 51.84 28.49 7.29 23.69 2.27 2.00 2.57 21.60 6.02 31.43 26.99

2 8 0.410 7.93. 4.70 48.97 30.49 7.03 24.45 2. 71 2.05 2.39 25.03 5.45 27.99 21.86 12 0.391 7.14 3.82 50.68 28.37 6.68 22.65 2.77 2.11 2.42 24.92 6.22 30.05 26.49

3 8 0.344 8.44 4.23 41.38 23.44 5.83 20.50 2.05 1.48 1.87 19.32 4.97 25.53 20.75 12 0.380 6.20 4.26 50.98 28.97 7.03 24.22 2.77 2.27 2.54 23.58 6.70 30.09 25.08

4 8 0.537 6.57 3.87 55.25 33.41 8.21 31. 71 3.54 2.64 3.13 25.48 -7.00 36.13 28.93 12 0.450 7.66 4.73 54.68 27.01 8.00 24.73 2.82 2.16 2.58 26.30 6.46 30.06 27.73

5 8 0.450 7.67 3.76 54.83 31. 71 8.09 24.42 2.86 2.29 2.58 24.70 6.65 32.55 26.71 12 0.427 7.54 5.25 53.74 29.46 8.29 26.00 3.03 2.16 2.59 23.51 6.56 29.29 28.32

MEAN 8 0.420 7.52 4.19 48.49 28.62 7.02 24.10 2.70 2.08 2.40 22.37 5.89 29.78 24.31 MEAN 12 0.414 7.06 4.49 52.39 28.46 7.46 24.26 2.73 2.14 2.54 23.98 6.39 30.18 26.92

MOR Modulus of Rupture MCS Maximum Crushing Strength FSPL - Fiber Stress at Proportional Limit MOE Modulus of Elasticity

Table 2. Mean values per age for physical and mechanical properties of bagras (Eucalyptus deglupta Blume) at different height levels

PROPERTY TESTED HEIGHT TREE MEAN LEVEL

67

8 Years Old 12 Years Old (I) (2) (3) (4)

Moisture content (%) Butt 141.01 149.33 Middle 134.53 135.04 Top 131.39 118. 70

Relative density 1 Butt 0.415 0.375 Middle 0.425 0.405 Top 0.420 0.454

Shrinkage from green to oven-dry (%)

Tangential Butt 7.75 7.45 Middle 7.50 6.98 Top 7.31 6.74

Radial Butt 4.33 4.35 Middle 4.13 4.30 Top 4.11 4.82

Static Bending

Modulus of rupture Butt 50.17 45.91 (MPa) Middle 46.74 53.05

Top 48.75 58.21

Stress at proportional Butt 29.76 26.45 limit (MPa) Middle 27.96 28.89

Top 28.14 30.04

Modulus of elasticity Butt 7.15 6.93 (GPa) Middle 6.98 7.65

Top 6.92 7.79

Compression of parallel to grain

Maximum crushing limit Butt 23.74 22.40 (MPa) Middle 24.40 24.56

Top 24.17 25.82

1 Based on volume at test and weight, oven-dry.

68

Table 2. Continued ...

PROPERTY TESTED HEIGHT TREE MEAN LEVEL

8 Years Old 12 Years Old (1) (2) (3) (4)

Compression perpendicular to grain

Stress at proportional Butt 2.75 2.55 limit (MPa) Middle 2.61 2.66

Top 2.73 2.98 Hardness

Side (kN) Butt 2.01 2.03 Middle 2.03 2.18 Top 2.21 2.22

End (kN) Butt 2.33 2.44 Middle 2.34 . 2.45 Top 2.53 2.72

Shear pa rallcl to grain

Maximum shearing Butt 5.64 6.28 strength (MPa) Middle 5.98 6.38

Top 6.04 6.51

Toughness (J) Butt 23.13 23.85 specimen Middle 22.45 23.66

Top 21.53 24.43 Cleavage

Splitting strength (N/mm width; length 76 mm)

In radial plane Butt 24.98 24.84 Middle 24.90 27.24 Top 23.07 28.69

In tangential plane Butt 28.53 30.17 Middle 31.57 28.44 Top 29.24 32.94

Sapwood thickness (mm) Butt 26 21 Middle 24 21 Top 24 21

Table 3. ANOVA results for physical and mechanical properties of bagras ( Eucalyptus deglupta Blume) between ages

F - V A L u E

SOURCE OF OF RELATIVE SHRINKAGE STATIC BENDING COMPRESSION HARDNESS SHEAR CLEAVAGE VARIANCE DENSITY Tangential Radial MOR FSPL MOE 11 to Grain 1 to Grain Side End Tangential Radial Tangential Radial

MCS FSPL

Age (A) 1.16 ns 2.94 ns 1. 10 ns 4. 70* 0.58 ns 1.94 ns 0.15 ns 0.23 ns 0.39 ns 4.36* 7.56* 0.30 ns 0.12 ns 6.59*

Trees/Age B 25.72** 11.29** 1.60 ns 9.22** 11. 19** 7.86** 29.71** 7.56' .. * 5.01** 11.48** 2.62* 6.11** 4.45** 2.51* (T/A)

Height/Age/ 20 3.52** 2.30* 0.75 ns 1.78 ns 1.68 ns 1.81 ns 3.18** 1. 06 ns 0.83 ns 2.26* 0.47 ns 1.65 ns 2.02* 1. 51 ns Tree

Table 4. Sumnary of variance components obtained for physical and mechanical properties expressed in terms of actual values CAV) and as percentages ~ c

of the total (%) between ages

SHRINKAGE STATIC BENDING COMPRESSION COMPONENTS OF RELATIVE Tangential Radial MOR FSPL MOE 11 to Grain 1 to Grain

VARIANCE DENSITY AV % AV % AV % AV % AV % MCS FSPL AV % AV % AV %

A 0.00037 1.48 0.05153 2.21 0.01915 0.57 5.3382 5.18 0 0 0.03378 1.52 0 0 0 0

VT 0.01713 68.74 1.3646 58.54 0.55417 16.53 59.3087 57.51 25 .4177 66.97 1.22634 55.02 20.2195 75.07 0.3530 67.29

0.00524 21.03 0.51735 22.19 0 0 16.8493 16.34 5.0544 13.32 0.43229 19.40 4.6017 17.09 0.0102 1.94

VE 0.00218 8.75 0.39775 17.06 2.7794 82.90 21.6342 20.98 7.4829 19.72 0.53625 24.06 2.1128 7.84 0.1614 30.77

TOTAL 0.02492 100 2.33123 100 3.35272 100 103.1306 100 37.955 100 2.2287 100 26.9340 100 0.5246 100

Table 4. Continued ...

COMPONENTS OF· HARDNESS SHEAR CLEAVAGE VARIANCE Side End Tangential Radial Tangential Radial

AV % AV % AV % AV % AV % AV %

A 0 0 741. 94 3.76 887.7255 22.11 0 0 0 0 5.7988 15.40

VT 7934.69 57.22 11582.07 58.74 1095.1240 27.28 1012.5819 50.85 15.5329 36.33 7.9587 21.13

0 0 4076.85 20.68 0 0 384.4647 19.31 13.7240 32.10 8.0480 21.37

VE 5932.57 42.78 3316.98 16.82 2031.3200 50.60 594.3200 9.94 13.5009 31.58 15.8536 42.10

TOTAL 13867 .26 100 19717.84 100 4014.1695 100 1991.37 100 42.7578 100 37 .6591 100

Table 5. ANOVA results for physical and mechanical properties of bagras ( Eucalyptusdeglupta Blume) per age of the trees

F·V A L u E SOURCE OF OF AGE RELATIVE SHRINKAGE STATIC BENDING COMPRESS JON HARDNESS CLEAVAGE SHEAR VARIANCE DENSITY Tangential Radial MOR FSPL MOE 11 to Grain 1 to Grain Side End Tangential Radial Tangential R~ial

MCS FSPL

T 8 46.44** 1.50 ns 1.86 ns 10.79** 25.45** 26.67** 5.19** 11.38** 9.92** 25.09** 5.72** 4.76* 2. 73 ns 7.81*

12 3.68* 2.72* 13** 4.79* 0.75 ns 1.40 ns 4.11* 3.14* 0.47 ns 0.41 ns 0.54 ns 0.55 ns 4.38** 1. 11 ns

H 8 0.60 ns 1.46 ns 0.31 ns 0.22 ns 0.56 ns 0.40 ns 0.52 ns 0.26 ns 1.03 ns 1.15 ns 1.94 ns 0.79 ns 0.24 ns 1.41 ns 12 6.65* 6.48** 0.17 ns 17.26** 4.58 ns 0.35 ns 13.25** 3.46 ns 0.86 ns 1.39 ns 1.11 ns 2.23 ns 0.13 ns 1.03 ns

TH 8 1.39 ns 0.31 ns 2.82* 0.90 ns 1.62 ns 0.61 ns 0.78 ns 0.50 ns 1.19 ns 0.60 ns 1.13 ns 1.15 ns 0.59 ns 0.03 ns

12 2.47* 0.80 ns 2.52* 0.7087 ns 1.28 ns 1.38 ns 0.47 ns 1.33 ns 0.43 ns 0.84 ns 4.15* 1.79 ns 0.40 ns 1.05 ns

Table 6. Surrmary of variance components obtained for physical and mechanical properties expressed in terms of actual values and as percentages of the total (%) per ages

SHRINKAGE STATIC BENDING COMPRESSION COMPONENTS OF AGE RELATIVE Tangential Radial MOR FSPL MOE 11 to Grain 1 to Grain

VARIANCE DENSITY AV % AV % AV % AV % AV % MCS FSPL AV % AV % AV %

\iT 8 0.01624 47.59 0.26743 6.23 0.15981 17.49 101.0810 76.54 53.6963 83.98 2.3636 76.64 38.1062 83.70 0.59795 77.58 12 0.00090 8.51 0.17811 5.77 1.0623 60.01 17 .1214 22.92 0 0 0.10063 6.66 2.3361 23.12 0.10772 28.22

H 8 0 0 0.09343 2.17 0.05951 39.36 0 0 0 0 0 0 0 0 0 0 12 0.00554 52.41 1.4158 45.84 0.30654 17.29 44.028 58.95 10.1198 48.16 0.3579 23.68 5.5175 54.60 0.07419 19.44

TH 8 0.00035 12.90 0 0 0.35951 39.36 0 0 3.9138 6.12 0.4444 14.41 5.4568 11.99 0 0 12 0.00175 16.56 0 0 0.30614 17.29 0 0 2.4110 11.47 0.29159 19.29 0 0 0.04903 12.84

VE 8 0.001818 39.58 3.9287 91.59 0.39418 3.79 30.9737 23.46 6.3302 9.90 0.27619 8.95 1.9645 4.31 0.17281 22.42 12 0.00238 22.52 1.49480 48.40 0.40175 22.70 13.5400 18.13 8.4819 40.37 0.76161 50.38 2.2512 22.28 0.15078 39.50

TOTAL 8 0.01841 100 4.2896 100 0.9135 100 132.0547 100 63.9403 100 3.0842 100 45.5275 100 0.77076 100 12 0.01057 100 3.0087 100 1.7702 100 74.6901 100 21.0127 100 1.5117 100 10.1048 100 0.38172 100

Table 6. Continued •••

COMPONENTS OF AGE HARDNESS CLEAVAGE SHEAR VARIANCE Side End Tangential Radial Tangential Radial

AV % AV % AV % AV % AV % AV %

VT 8 16953.3833 71.31 23882.3945 67. 73 32.0738 54.37 18.4424 52.09 1588.0605 36.54 1885. 1898 51.82 12 0 0 0 0 0 0 0 0 602.1876 31.58 139.9740 23.68

H 8 30.2866 0.02 682.3800 1.94 3.8332 6.50 0 0 0 0 68.2491 1.88 12 0 0 1748.25 32.33 4.7570 14. 75 6.9702 26.15 0 0 74.0825 12.53

TH 8 1088.475 4.58 7722.6084 21.94 2.7081 4.59 2.2628 6.39 0 0 853.7353 23.47 12 0 0 0 0 20.8641 64.69 2.6791 10.05 0 0 19.0123 3.22

VE 8 5702.4667 23.99 2973.9333 8.43 20.3713 34.54 14.7030 41.52 2757.9507 63.46 830.6387 22.83 12 6162.6667 100 3660.0333 67.67 6.6306 20.56 17.0042 63.80 1304.6893 68.42 358.0013 60.57

TOTAL 8 237,74.6117 100 35261.3162 100 56.9864 100 35.4082 100 4346.0112 100 3637.8129 100 12 6162.667 100 5408.2833 100 32.2517 100 26.6535 100 1906.8769 100 591.0701 100

74

other strength properties as shown by a similar trend of variation in physical and mechanical properties at 12 years. At any rate, there was a consistent increase in the physical and mechanical properties from butt to top.

The trend of variation in relative density indicates that wood in the crown is basically denser than at the butt and middle. The similar trend of variation in strength properties can be attributed to the predominant effect of relative density.

Except in shrinkage (radial) interaction between trees and height at 8 years old was insignificant. At 12 years old, it was significant in relative density, shrinkage and cleavage (tangential). The variance components amounted to 39.36% for shrinkage (radial) in 8 years old, and 16.56%, 17.29% and 64.69% for relative density, shrinkage and cleavage, respectively, in 12 years old.

The strength classification (Table 7) indicates that 8-year old bagras trees fall under moderately low strength (C4) except in compression parallel to grain where the value falls under medium strength (C3). At 12 years old, the strength properties are classified under medium strength (C3) except in compression perpendicular to grain (C4).

CONCLUSIONS

• The strength properties tend to improve from 8 to 12 years old. However, the age effect is not statistically significant except for MOR (SB), hardness (end) and shear (tangential) with small total variance components of little practical significance.

• The slightly higher relative density value at 8 years than at 12 years may be due to the random variation among trees.

• The similar trend in variation for relative density and strength properties at 12 years indicates the predominant effect of the former on the latter.

• Discarding the effect of possible factors which somehow affect the test values, i.e., differences among trees due to tension wood, sampling procedure, silvicultural treatment, genetic diversity and others, the results indicate that bagras falls under moderately low strength (C4) at 8 and 12 years old. Therefore, rota ti on age of bagras can be at 8 or between 8 and 10 years instead of 12 years ~or end uses requiring moderately low strength properties.

RECOMMENDATION

There is a need to study further the large differences among trees. The possible factors which account for the wide variation should be examined to determine the extent of their effect on wood utilization.

75

Table 7. Physical and mechanical properties grouping/classification (Espiloy 1977)

AGE/HEIGHT LEVEL PROPERTY TESTED 8 YEARS OLD 12 YEARS OLD

Butt Middle Top Mean Butt Middle Top Mean

Relative density MLRD MLRD MLRD MLRD MLRD MLRD MLRD MLRD

Volumetric shrinkage from green to oven-dry MVS MVS MVS MVS MVS MVS MVS MVS

Static bending

Modulus of rupture (MPa) C3 C4 C4 C4 C4 C3 C3 C3

Modulus of elasticity (GPa) C4 C4 C4 C4 C4 C3 C3 C3

Compression parallel to grain

Maximum crushing strength (MP a) c3 C3 C3 C3 C4 C3 c3 c3

Compression Perpendicular to grain

Stress at proportional limit CMPa) c4 c4 . c4 C4 c4 c 4 c4 c4

Shear parallel to grain

Maximum shearin~ strength (MP a) C4 C4 C4 C4 C3 C3 C3 C3

* Based on Kelseys formula of determining volumetric shrinkage (VS) = R + T · RT/100

MLRD . Moderately low relative density MVS . Medium volumetic shrinkage c3 . Medium strength C4 . Moderately low strength

REFERENCES

ALONZO, D.S. 1977. The effect of fertilization on some physical, anatomical and chemical properties of Gmelina arborea. Unpubl. MS Thesis. UPLB Graduate School.

AMERICAN SOCIETY FOR TESTING AND MATERIALS. 1972. Annual Book of ASTM Standards. ASTM Dl43-52.

ESPILOY, E.B. Jr. 1977. Strength grouping of Philippine timber species for structural purposes. NSDB Technol. J. 2(4): 76-85.

KELSEY, K.E. and R.S.T. KINGSTON. 1953. An investigation of standard method of determining the shrinkage of wood. J. For. Prod. Res. Soc. 3(4): 49-53.

76

LANTICAN, C.B. 1975. Variability and control of wood quality. Inaugural lecture as SEARCA Professional Chair Holder in Wood Quality. UPLBCF, College, Laguna.

LAURICIO, F.M and R.Z. DELA CRUZ. 1969. New sampling plan to promote mechanical testing of Philippine woods. The Phil. Lumberman 15(5).

MENIADO, J.A. 1978. Wood quality and utilization of Philippine plantation species. Bagras (Eucalyptus deglllpta). Proceedings 1st IUFRO Conference on Wood Quality and Utilization of Tropical Species. Oct. 30 - Nov. 3, FORPRIDECOM, College, Laguna.

T AMO LANG, F.B. and J.E. ROCAFOR T. 1986. Physico-mechanical properties and possible uses of some plantation-grown species in the Philippines. FPRDI Library, College, Laguna.

THE CRITICAL 'LOAD OF TIMBER COLUMN OF VARIED SLENDERNESS RATIO

Enrique B. Espiloy, Jr.1

ABSTRACT

Apitong, bagtikan, yakal, mayapis, tangile and red lauan species commonly used as compression members in timber-framed structures, were tested for their critical stress (Cp) in compression under varied slenderness ratio ( L/ D) at "pin-end" condition.

Findings indicated that the Cp of a column depended on the material's L/ D, the maximum compressive stress (Cm), and modulus of elasticity ( E). The C p for long columns depended mostly on E and L/ D, while that of the shorter columns with L/ D less than 25 depended on the Cm and E.

Based on the empirical behaviors, relationship models were formulated. Regression techniques were applied to determine the coefficients of the models so that these could be expressed in the form of designer's equations. Test of non-zero hypothesis on the coefficients for the models formulated showed that long columns behaved in accordance with the Euler formula, and that its coefficients were also applicable to the expression of Cp derived for the intermediate/short columns.

INTRODUCTION

Without fundamental knowledge on the be ha vi or of individual structural members, successful structural design is practically impossible. In a structure, the members are so designed to resist either external or internal loads and may act as beam, column, tension, a combination of beam and column, or tension. Although the column is an important unit in any structure, only a few studies have been conducted to derive their allowable strength compared with a number of studies on the structure of beams or transversely loaded members. Previous studies on columns have been done mostly in the U.S., Australia and the United Kingdom.

Timber column design practice in the Philippines is based from test results on columns from the U.S. timber specie3 (Carillo 1972). Such practice is irrational because temperate softwood and tropicai hardwoods possess different properties. The properties of some local softwoods vary from those of temperate softwoods. Moreover, Philippine wood species cover a wide range of densities not covered by American woods (Rocafort et al. 1983).

Hence, a column formula applicable to Philippine wood species is desirable to attain a safe and economical design. It should also be simple (i.e., requiring only the basic properties of the timber

1 Researcher, Housing and Materials Division, FPRDI, DOST, College, Laguna

4031.

78

material used), but effective estimating the critical load.

Objectives

I. To investigate the short columns compressive load.

behavior under

in

of pure

2. To determine the critical or buckling loads of short/intermediate and long columns

3. To formulate mathematical expressions that approximate the critical load a solid wooden column can carry under a wide range of slenderness ratio (L/D) at "pin-end" condition.

Review of Literature

A column is a compression member in a structure whose cross-section is more slender than its length. Columns arc usually classified as long or intermediate. Sometimes the short compression block or strut is considered a short column.

The factors affecting the load-carrying capacity of columns may diff cr from those affecting the strength of beams or laterally-loaded members. In beams, the ultimate stress in the extreme fibers depends on the span and cross­section. In columns, the critical stress is not always equal to the maximum load divided by its cross-sectional area because the critical stress is by no means equal to the ultimate compressive strength of the material (Sloane 1952). In other words, the critical stress of a column depends on its slenderness ratio (L/D) - the ratio of its unsupported length (L) to its least dimension (D). While short compression block generally fails by crushing and shearing action, long

columns fail by bending or buckling. In between the short and long columns are the intermediate columns that fail in a combination of crushing, shearing and bending. It is this intermediateness that .gives rise to formulas for intermediate columns designed for various construction materials such as steel, concrete and wood (Shanley 1957).

The first to develop empirical column formulas for wood is the U.S. Forest Products Laboratory (Newlin and Gahagan 1930). Based on their studies, the critical load of columns, whose L/D is not more than I 0, is equal to the basic compressive stress of the wooden material used. For long columns, the Euler's formula is used but modified to

give a safety factor of 3. The critical load in the intermediate columns follows the fourth-degree-para bola in which th:~ L/D actually makes the critical load equal to two-thirds of the basic compressive stress of the material.

The intermediate column design adopted by the Australians, which they claim will give an accurate a pproxima ti on of the critical load for their local species, is the Secant Formula (Pearson 1954). This formula, however, is too complicated -- it can only be solved by trial-and-error or graphical methods (Pearson et al. 1958). Its use is facilitated by providing the designers with data in the form of tables and graphs (SAA 1975).

On the other hand, work undertaken at the U.K. Forest Products Research Laboratory by Nevard and Pettifor (1944) on European red wood columns showed that these behave in accordance with the Perry Strut formula. This was confirmed by Sunlcy (1955) who found that the formula was also suitable for Douglas fir, Sitka spruce and Scots pine.

The Russians also designed their long columns using the Euler's Formula which was modified to give a certain degree of safety factor (Karlescn ct al. 1967). However, in their design of short and intermediate columns, the critical stress is obtained by multiplying the ultimate compressive stress by a correction factor which is proportional to the ratio between the material's ultimate comprcssi ve strength and modulus of elasticity.

Canadian engineers design their timber columns using the U.S. formulas (FPLD 19 51 ). This is also true in the Philippines as specif icd under her local code of practice (PACE 1965, ASEP 1988).

MATERIALS AND METHOD

Six commercial species commonly used for compression members in structures such as apitong (Dipterocarpus grandiflorus Blanco), bagtikan (Parashorea plicata Brandis), mayapis [Shorea squamata (Turcz.) Dyer.], red lauan (Shorea negrosensis Foxw.), tangile [Shorea polysperma (Blanco) Merr.] and yakal (Shorea astylosa Foxw.) were selected for this study.

The completely randomized design procedure of sampling was applied. Each species was represented by five flitches purchased from several lumber yards near the Forest Products Research and Development Institute (FPRDI). Each flitch, 75 x 100 x 2440 mm in dimension, was divided into four sticks and processed into 20 x 35 mm cross sections. Out of the 4 sticks, a set of column specimens was taken reprcscn ting 5, 7 .5, I 0, 15, 20, 25, 30, 35, 40, 45 and 50 L/D. Control specimens, one each for static bending (20 x 20 x 320 mm) and compression parallel to the grain (20 x 20 x 60 mm) were -also taken from each flitch. A

79

total of 65 specimens was taken from the 20 sticks out of the five flitches representing a single wood species.

For each species, the varia blcs investigated were the critical stress (Cp) of a column for a corresponding L/D, modulus of elasticity in bending (E) and the ultimate compressive strength (Cm) of the wood material. Also investigated for additional information were the specific gravity (Sg) and moisture content (MC) taken from the control specimens. General principles of engineering mechanics of materials was applied to establish formula models based on the trends of the variables relating the Cp of the columns.

In fabricating the specimens, the following measures were maintained to eliminate influence on the column 5tren gth: a. the tangential surfaces were oriented along the wider cross section; b. the cross section throughout the length was straight and uniform; c. the specimens were free from defects such as knots, cross-grain, slope of grain, etc.; and d. their ends were cut perpendicularly to their length.

Strength tests (compression parallel to the grain and static bending) on the control specimens were performed in accordance with the British standard methods (BSI 1957). Static bending test was carried out by the central loading method and the ends "freely" supported. Loading was applied gradually at a constant speed of 2.5 mm/min and deflection readings at the mid-span were measured by means of dial gauge for every convenient load interval until failure was reached. The modulus of elasticity (E) was computed using the standard formula found in most engineering textbooks.

Compression parallel to the grain test was carried out with care. As stated

80

earlier, the ends of the test piece were made essentially smooth and parallel and normal to the longitudinal axis so that the loading plates between the specimen were parallel to each other during the entire test period. Without such precautions, the observed strength values might be considerably below the standard values. Loading was applied at a constant rate of 0.6 mm/min until the maximum load was reached. The ultimate compressive stress (Cm) was computed by dividing the maximum load with the cross-sectional area of the piece.

During critical load tests for the various L/D columns, loading shoes were provided to allow the column specimen ends to rotate and follow a pre-determined buckling action as the load was applied. Without these supports, the ends will resist buckling and tend to introduce undesirable stresses. To avoid eccentricity in loading, the column specimen was carefully aligned vertically with the aid of two plumb bobs, of which one was placed along the width and the other along the thickness. Loading was then applied at the rate of 0.6mm/min until the column buckled or reached the critical load. The piece was then removed from the loading shoes and rotated 180° on its longitudinal axis. Again, loading was applied after the proper alignment. If higher critical load was noted in the second test, this load was considered as the apparent critical load otherwise the observed critical load during the first test was considered. The critical stress (Cp) was obtained by dividing the critical load by the cross-sectional area of the column specimen,

This study was confined to the testing of small defect-free column specimens at green condition. Only columns with ••pin-end" restraint at both ends were

considered, since this type of restraint was the fundamental case in design calculations.

RESULTS AND DISCUSSION

Table presents some important properties of the six species investigated, i.e., average values of static bending and compression parallel to the grain of the control specimens. The average values were based on the results of five tests taken from the five flitches representing a single species. Although the species' MC and Sg were not considered essential in deriving the column formula, these properties taken from compression parallel to grain of control specimens were included as added inf or ma ti on.

Table 2 shows the results on the critical load (Cp) of freely supported columns with their corresponding L/D ratios. For simplicity of presentation, the figures indicated by the L/D in Table 2 were nominal values. The actual L/D values deviated from their nominal values depending on the actual measurements of the specimens' lengths and thinner dimensions. In the analysis of results, however, the actual L/D values were the ones considered. The Cp values given were also the average values of five specimens taken from five flitches representing a single species.

Ta blc 2 indicated that the Cp decreased when the L/D increased (similarly shown in Figure 1 ). From inspection, the point of inflection was around 25 L/D. The trend suggests that the strength for long column or the Cp depends mostly on the modulus of elasticity (E) such that

Cp = aE/(L/D)b (I)

where a and b arc constants.

81

Table I. Properties of the six timber species

SPECIES PROPERTY

MC(%) Sg Cm (MPa) E (1000 MPa)

A pi tong 69.8 0.525 30.8 13.6

BagtikaP 89.3 .518 31.5 11.4

Red Lauan 78.2 .523 26.4 8.9

Maya pis 102.9 .468 29.l 10.5

Tangilc 72.3 .489 25.0 9.9

Yakal 42.7 .711 48.4 15.4

·able 2. Critical stresses (Cp), in MPa, of freely-supported columns of varied slenderness ratio (L/D

S P E C I E ·S NOMINAL SLENDERNESS RATIO (L/D) 5.0 7.5 10 15

Apitong 30.5 28.8 27.9 27.0

Bagtikan 30.4 28.7 27.5 24.7

Red Lauan 25.8 24.8 24.3 23.1

Mayapis 28.0 27.3 26.4 22.7

Tangile 24.7 23.6 22.8 21.5

Yakal 47.0 45.3 43.5 41.6

On the other hand, the strength behavior of short and intermediate columns with smaller L/D seemingly depends on Cm and E of the material. This trend may be represented by

Cp = Cm [1-A (L/D)b] (2)

where A and b are constants.

20

25.4

21.1

21.5

19.3

19.4

36.8

25 30 35 40 45 50

18.7 15.7 10.7 8.0 6.0 4.6

13.9 9.5 7.2 5.6 4.0 2.9

15.5 10.2 7.9 6.8 5.6 3.5

16.3 11.8 10.1 7.0 5.6 4.5

15.9 12.5 8.8 6.6 5.6 4.2

24.1 17.9 13. 1 9.2 7.2 5.9

At the point of inflection (Fig. 1), equations (1) and (2) are equal and have a common tangent with slope of dCp/d(L/D). Hence,

aE(L/Df b = Cm-A Cm (L/D)b (3)

Differentiating (3) with respect to the L/D gives

82

0

Shor! /in fermediafe column curve

/0 2o

•

App_roximafe /ocafion of a poinf tit- inFlecfion dividln9 fhe intermetliale/sltorf column and long column curves

long column curve

30 40 L/0 Ratio

Fig. 1. Typical curve showing the relationship between the critical load and L/D ratio of timber columns.

aE = A Cm (L/D)2b

Combining equations (3) and (4):

(L/D)b = 2aE/Cm

(4)

(5)

Equation (5) represents the L/D at the point of inflection of the two curves separating long and short or intermediate columns. From Figure 1, the value of L/D is more or less 25. If (5) is substituted in (4), then

A= Cm/4aE (6)

Finally, substituting (6) in (2) will give

Cp '= Cm [l-(Cm/4aE) (L/D)b] (7) or

(4E/Cm)[l-(Cp/Cm)] = (L/D)b /a (7')

Equation (7') can now be used as a model in deriving the general

expression for intermediate and short columns, while equation (1) is for fitting regression for long columns. The only remaining problem is to determine the values of the constants a and b. The constants can be determined conveniently with the aid of linear regression techniques. The curve in (7') may be linearized by taking the logarithm on both sides. Thus,

Log Y' = b log X' - log a (7")

where: Y' = (4E/Cm) [I - (Cp/Cm)], and X' = L/D. Equation (7 11

) is the same as the linear regression model Y = Bq + B1 X where: Y = log Y', X = log X , Bo = log a, and B 1 = b.

Likewise, if the curve in (1) is transformed into

Cp/E = a/(L/D)b (I')

i t m ~1 y b c I i n ea r i z c d. bCl'Oll1CS

Thus, (l')

Log Y' = log a -b log (L/D) (l ")

where: Y' Cp/E, and X' L/D. Equation (1") is also the same as the line::ir regression model Y =Bo + B1X where: 'r' = log Y', X = log X', Bo = log a, and B 1 = b.

Table 3 shows the sums of statistical logarithmic values of variables computed from each species for the intermediate columns, while Table 4 presents the values for long columns. Also shown in the two tables arc the aggrcga te values of variables constituting the six species studied. The values arc essential in estimating the constants a and b for equations (1) ~and (7), or the regression· coefficients B0 and B 1 using the linear regression model Y = B0 + B 1 X with reference to equations (1 ") and (7").

Table 5 shows the estimated values of constants a and b including their respective correlation coefficients (r). Generally, there was a high degree of relationships between the variables studied. As estimated from each species, constant a ranged from 0.729 to 1.363 for intermediate column, and from 0.678 to 2.475 for long column relationships. Constant b, on the other hand, ranged from 1.877 to 2.114 for intermediate column and from 1.882 to 2.346 for long column relationships. Considering all species, the values of constant a were 1.154 and 1.127 for long and intermediate column relationships respectively. The values of constant b were equal to 2.059 for long columns and 1.950 for intermediate columns. The trend suggests that constant a values for intermediate columns also corresponded to constant a values for long column

83

relationships. This was also true for constant b values. Thus, the constants could be estimated either from the data o btaincd from long or from intermediate/short columns. This was expected since the two curves had a common tangent at the point of inflection.

Note that the estimated constants a and b resembled those of the constants f o.r. the Euler curve, Cp/E = rr 2

/

'[12 (L/D)2] In this case, the constant

rr 2/12 (or .822) signified the value of constant a and that the exponent 2 of LLD signified constant b [or Bo = log rr/12 and B 1 = 2]. Thus, it was hypothesized that the estimated values of the constants a and b (or the estimated regression coefficients Bo and B 1 corresponded with those of the constants of the Euler curve ..

Table 6 shows the results of the computed t-values and their level of significance. The hypothesized values of the constants were accepted since the computed t-values were less than the ta bu lated values for fheir respective degrees of freedom at 5% probability level. Hence, a = rr 2/12 and b = 2. Adopting the val.ues of a and b from the foregoing, equation (1) for the long column can be rewritten as:

Cp = rr 2 E/[12 (L/D)2] (8)

and equation (7) for intermediate columns as

Cp = Cm [1 - (3 Cm/rr2 E)(:-. /D)2] (9)

The point of inflection separating the long and the intermediate column described by equation (5) by the L/D can be rewritten as

L/D = rt ""E/6 Cm (10)

84

Table 3. Sums of statistical logarithmic values of variables for intermediate columns

S P E C I E S VARIABLES TOTAL

Apitong Bagtikan Red Lauan Mayapis Tangi le Yakal

EX 74.250275 75.414501 75.154162 75.149264 74.741704 74.978729 449.688635

EY 147.471835 158.489564 143. 779915 154.179249 149.163475 145.119165 898.203203

Ex2 192.544288 197.881919 196.541456 196.870547 194.647822 195.846561 1174.332593

~y2 779.598629 881.913523 727.866381 840.124640 781.019359 740.082477 4750.605009

~XY 383.539758 414.840617 375. 715054 402.888001 387.444343 378.739625 2343.167398

n 30 30 30 30 30 30 180

Table 4. Sums of statistical logarithmic values of variables for long columns

S P E C I E S VARIABLES TOTAL

Apitong Bagtikan Red Lauan Mayapis Tangile Yakal

.Ex 106.856920 107.916606 107.760228 107.719686 107.266246 107.722307 645.241993

Ev -219.160873 -226.026973 ·213.157974 -214.358432 ·213.592404 ·216.463076 · 1302. 759732

Ex2 382.183876 389.805465 388.689669 388.399706 385.166013 388.471586 2322.716315

Ev2 1609.713055 1713.339558 1521.806702 1538 .. 108280 1527.937572 1569.775817 9440.680984

Exv ·783.827413 ·816.836280 . 768.846867 . 772. 727179 . 766.994124 -780.780051 ·4690.011914

n 30 30 30 30 30 30 180

• 85

Table 5. Estimated constants for intermediate and long columns based from their regression models

SPECIES INTERMEDIATE COLUMN LONG COLUMN Estimated Constants Correlation Coefficient Estimated Constants Correlation Coefficient

a b (r) a b (r)

Apitong 0.729 2.114 0.847 0.951 2.037 0.867

Bagtikan 1.363 1.978 0.853 2.475 2.346 0.921

Red Lauan 1.093 1.877 0.867 0.976 1.971 0.929

Mayapis 1.345 1.933 0.822 0.678 1.882 0.941

Tangile 1.351 1.875 0.868 1.086 2.014 0.958

Yakal 1.098 1.898 0.894 1.423 2.108 0.969

All species 1.127 1.950 0.849 1.154 2.059 0.892

Table 6. T·values on the non·zero hypothesis on the estimated regressicm coefficients, s0, s1 and s0+s1

SPECIES INTERMEDIATE COLUMNS HYPOTHESIS ON LOG COLUMNS HYPOTHESIS ON B

0 ·0.195 s, = 2.000 B

0 +s1 = 1.805 B =

0 ·0.195 s, = 2.000 80+81 1.805

Apitong 0.189 ns11 0.453 ns 0.014 ns 0.184 ns 0.167 ns 0.497 ns

Bagtikan 0.862 ns 0.095 ns 1.322 ns 1.641 ns 1.859 ns 1.555 ns

Red Lauan 0.546 ns 0.601 ns 0.499 ns 0.321 ns 0. 194 ns 0.518 ns

Mayapis 0.757 ns 0.263 ns 1.049 ns 0.420 ns 0.926 ns 0.225 ns

Tangile 0.961 ns 0.617 ns 1.157 ns 0.680 ns 0.126 ns 0.893 ns

Yakal 0.629 ns 0.567 ns 0.654 ns 1.491 ns 1.054 ns 1.657 ns

All species i.535 ns 0.553 ns i .826 ns 1.205 ns 0. 754 ns 1.377 ns

l! ns · not significant

86

CONCLUSION AND RECOMMENDATION

•

The formulas in equations (8) and (9) predicting the Cp of columns are based on the actual strength properties of the material investigated. For safety design purposes, the Cm and E should be adjusted accordingly to account for the variability of the material, effect of long-duration loading, defects and a provision of a safety factor in accordance with the strength grouping system of Philippine timber species presented in an earlier report (.Espiloy 1984). In that report the overall reduction factor applied to Cm to arrive at safe basic working stresses (S'c in Mpa) was about 1/2.15 but no provisions were applied to E (in MPa) because: a. the safety of structure was not determined by the E, and b. the degree of rigidity required for a structure was frequently arbitrary in nature. In cases involving instability such as in columns, it is recommended that the E be adjusted by a reduction factor of 0.6 or 1/1.667.

From the foregoing considerations, the critical load of the columns indicated by equations (8) and (9) will now be:

1t2E

Cp = for long columns, 20(L/D)2

REFERENCES

and

[ 5S'c 1 Cp = S'c. 1 - --- ---- (L/D)2 1t2E

for intermediate/short columns, where S'c is the basic working stress in compression parallel to grain and E is the average E. The point of inflection separating the long and intermediate columns as defined by L/D in equation (10) becomes

L/D =,cf E .. lOS'c

The factors for the effective lengths (L} to calculate the L/D for use in the formula are considered a unity since their derivations are based on columns with ends under "pin-end" condition. The effective lengths in this study are assumed to be the distance between two adjacent points of zero bending moment, these being two po in ts between in which the deflected member would be in single curvature. For purposes of calculating the L/D other than columns pinned on both ends, e.g., those restrained at both ends in position but not in direction, it is suggested that their dfective lengths be modified as recommended in most timber design handbooks.

ASSOCIATION OF STRUCTURAL ENGINEERS OF THE PHILIPPINES 1988. National Structural Code of the Philippines. Vol. I. 3rd ed. ·

BRITISH STANDARDS INSTITUTION. 1957. Testing small cleur specimens of timber. BS 373. British Standard Institution, London.

CARILLO, A.B. 1972. Structural design data and specifications. 6th ed., Ken Inc., Q.C., Philippines.

87

ESPILOY, E.B. JR. 1983. Simplified sets of working stresses of timber through strength grouping system. Paper presented during the FPRDI 26th Anniversary- Symposium, 15 July 1983, FPRDI, Los Banos, Laguna.

FOREST PRODUCTS LABORATORY DIVISION. 1951. Canadian woods, their properties and uses. 2nd Ed. Forestry Branch, Forest Prod. Lab. Div. King's Printer and Controller of Stationary, Ottawa.

NEV ARD, E.A. and C.B. PETTITOR. 1944. Formulation of safe working stresses for struts. Drafting Committee CP 112. Forest Products Research Laboratory, U.K. Unpublished paper.

NEWLIN, J.A. and J.M. GAHAGAN. 1930. Testing of large timber columns and presentation of the Forest Products Laboratory Formula. Tech. Bull. No. 167. U.S.D.A., Washington, D.C.

PHILIPPINE ASSOCIATION OF CIVIL ENGINEERS. 1965. Timber design standards. PACE CP 202. Philippine Association of civil Engineers, Manila.

PEARSON, R.G. 1954. The strength of solid timber columns. I. Tests of short duration on model columns. II. Estimation of the strength of timber columns. J. Appl. Sci. 5(4): 363-402.

, N.H. KLOOT and J.D. BOYD. 1958. Timber engineering design ------handbook. CSIRO, Melbourne University Press, Australia.

ROCAFOR T, J.E., J.A. PARAYNO and Z.L. CABRAL. 1983. Progress report on the relative density of Philippine woods. The Phil. Lumberman 29(1): 39-53.

STANDARD ASSOCIATION OF AUSTRALIA. 1975. SAA timber engineering code. Australian Standard 1720-1975. SAA Standard House, Sydney.

STANLEY, F.R. 1957. Strength of materials. McGraw-Hill, p. 582-588. In Wooden structures. 1967. G.G. Karlsen et al. (eds.). MIR Publishers. Mosco.

SLOANE, A. 1952. Mechanics of materials. The MacMillan Co., New York.

SUNLEY, V.G. 1955. The strength of timber struts. Forest Products Special Report No. 9. Dept. of Sc. & Inc. Res. HMSO, London.

UNITED STATES DEPARTMENT OF AGRICULTURE. 1964. Linear regression methods for forest research. U.S. For. Service Res. Paper FPLI 7. USDA, Washington, D.C.

LAMINATED VENEER LUMBER (LVL) FROM INDUSTRIAL TREE PLANT AT ION SPECIES: YEMANE (Gmelina arborea R. Br)

Hilario C. Dolores, Emmanuel Noli B. Sicad and Felisa D. Chan 1

ABSTRACT

Laminated veneer lumber ( LVL) were produced from 6.5 and JO mm thick yemane (Gmelina arborea R. Br.) veneers. The process consisted of rotary cutting of the bolt. drying Lhe veneers to 8% moisture contenl and gluing the veneers parallel to each other using phenol-resorcinol formaldehyde resin.

The ef fee ts of pressing pressure and time on the modulus of rupture (MOR) and glue bond quality of LVLs were investigated.

Specific pressure significantly influenced the MOR parallel to the lamina. LVL from 6.5 mm veneers had higher MOR and glue bond properties than LVL from JO mm veneers. However, LVL of both thicknesses had superior properties compared to solid sawn lumber of the same dimension.

The 6.5 mm LVL was greatly affected by specific pressure and pressing time. The higher the specific pressure and pressing time, the better the development of glue bond.

INTRODUCTION

With the dwindling timber resources in the country, the optimum utilization of fast growing ind us trial tree plan ta ti on species (ITPS) by product engineering should be considered.

At present, the housing industry is deprived of quality lumber from ITPS for specific structural purposes due to the present sa wmill.lng practices of comprom1smg lumber strength properties in favor of lumber recovery. Also, there is heterogeneity or varhbility in the quality of lumber produced because of natural defects

present in the wood. Furthermore, the sizes and quality of lumber from ITPS depend on the log quality and diameter which are generally low and small, respectively, when compared to naturally-grown trees.

With these constraints, the housing industry needs a product that is structurally stable and of prcdicta ble quality from ITPS logs. The engineered product ref erred to is the laminated veneer lumber (L VL). L VL is a composed wood board manufactured from jointed veneer

1 Researchers, Housing and Materials Division, FPRDI, DOST, College, Laguna, 4031.

sheets. Unlike plywood where the veneer grains arc in opposite direction, the LYL is laid up with the veneer grains running in the same direction.

LYL sizes range from 100 to 1,200 mm wide, 2.5 to 25 m long and up to 75 mm thick. Being dimensionally sta blc, with uniform strength and more versatile than sawn timber, L VL can be used where structural sawn timber arc required. As a product, it can command a higher price than either plywood or structural sawn timber.

H.eview of Literature

Though the manufacturing processes for L VL and plywood arc quite similar, they significantly differ in the laying up, pressing and fin al processing.

Compared to sa wmilling, L VL offers numerous advantages. According to Behler (1972), the L VL processing from log to finished product takes only 30 minutes with a 60% yield. This contrasts with the processing time of 5 days or more and a 40% yield for conventional softwood lumber. Also sawdust is minimized by three-fourths, consequently lessening the health and environmental risks during LVL production. Preliminary estimates at the U.S. Forest Products Laboratory indicate that L VL parts provide savings over solid wood parts even though the farmer's cost per cubic meter is greater. The savings come from the increased product yield per cubic meter, elimination of kiln-drying of stocks, reduced handling cost and degrade in the rough mill, and elimination of planing.

Materials from low value sawn timber trees, trimmings, crooked logs and logs too short for conventional lumber can be processed into L VL. Only the

89

stronger, mature wood in the core is peeled into L VL with the use of rotary peeler. This a voids variation in the modulus of elasticity (MOE) if juvenile wood is used. Moreover, the strength­reducing defects normally present in veneer are dispensed in the L VL, resulting in reduced variability. This is important because the derivation of working stresses considers variability. Thus, a decrease in MOR values in L VL tends to increase its allowable working stresses.

L VL manufactured from low-grade Siberian larch logs show a considera blc increase in strength properties (Sagaki 1979). The joist bending properties of a 2 x 4-inch solid Siberian larch arc: MOR of 486 kg/cm2 and MOE of 123 x 103 kg/cm2, with standa·rd deviations from the mean (SD) of 143 and 25.33 respectively. An 8-ply L VL has an MOR of 521 kg/cm2 and an MOE of 138 x 103 kg/cm2, with SD's of 87 and 18 respectively. These findings suggest that L V L is a potential material for structural purposes.

In Japan, studies on the use of L VL for long box columns showed that the L VL's mechanical behavior coincides with the theory of the rigid framed structure (Okuma 1981).

The strength properties of rotary knife-cut laminated Southern pine were determined by Moody and Peters (1972). The press-lam material from 4-1 /2-inch thick clear plies averaged 18% or less in MOR and 5% or less in MOE than small, clear samples of sawn lumber after normal conditioning procedures. Shear strength of the press-lam material was lower, yet averaging 67% in the tangential direction and 59% in the radial direction. The value in the radial direction was expected due to the deep lathe checks which developed in the 1/2-inch thick veneer during rotary

90

cutting. Accelerated aging tests indicated that the press-lam material's bending and shear properties rema i necl at par with the solid sawn wood after seven simulated weathering conditions.

In assessing the glue-laminating characteristics of five plantation species (viz., yemane, bagras, Benguet pine, giant ipil-ipil and teak), Chan et al. (1988) found that except for teak, all are easy to glue and durable when phenol-resorcinol formaldehyde resins are used.

Schaff er (1972) noted that the press­lam processing system of rotary cutting thick veneer, press drying, and laminating into sheets promises an average 50% improvement in dry product yield over that normally obtained by growing Southern pine. The most serious processing defect found to affect product performance is the knife checks parallel to the gr'ain of thick veneers. These checks reduce the bending and shear properties of small clear specimens but do not seriously affect the bending properties of structural joists.

In another investigation on the mechanical properties of laminated modified wood from 17 ply panels of l / 16-inch rotary-cut veneer, Erickson (1982) found that the wood's moisture resistance is greatly improved by resin impregnation. The only substantial increase in strength is in compression, no ta bl y across the grain. Resin treatment improves the stiffness of all species and to some extent the shear in the plane of the plies, but it reduces the tensile, toughness and highest strength of wood. Resin impregnation bf ply compression results in a general increase in all properties except toughness and impact strength. Compression to a high degree at elevated temperature without resin

i mprcgna ti on leads to a general i ncreasc in most properties in proportion to the increase in density.

L VL from fast-growing species has numerous applications. In Europe and America it competes well with steel, glulam and sawn timber. Fire-resistant boards can be made from L VL which are chemically-treated before lay-up. This treatment, along with uniform strength properties, makes L VL an ideal material in load bearing structures for roofs and floors. It can also be used as window and door stocks, scaffolding, interior walls and furniture as framing, or if ovcrlayed with veneers, as a decorative component.

According to Lyons (1982), the American Plywood Association (APA) has predicted that by the year 2010 the structural panel industrv will generate markets for 4 billion ft2 of structural panels.

This study attempted to determine the technical feasibility of producing laminated veneer lumber from an ITPS.

Objectives

1. To establish the optimum conditions in the manufacture of LVL.

2. To determine the mechanical and glue bond strengths of laboratory­fa bric a ted L VL.

MATERIALS AND METHODS

Materials

Yemane (Gmelina arborea R. Br.), an ITPS, was used in the production of veneers. The logs were collected from

the Magat Reforestation Project in Diadi, Nueva Vizcaya.

Phenol-resorcinol formaldehyde resin ( 450/o solids) with its corresponding catalyst served as binder.

Production of Veneers

Veneers 6.5 and 10 mm thick were rotary cut with a 137-cm rotary lathe and clipped into 127 x 125 cm sheets. These were then dried in the FPRDI mechanical roller veneer dryer at 150°C to approximately 60/o MC, the recommended veneer moisture content using phenol-formaldehyde resin in plywood manufacture.

Production of Laboratory Test Pieces

Three conditions were observed in the manufacture of L VL.

Variables

1. Pressing pressure, kg/ cm

2. Pressing time, min.

3. Veneer thickness, mm

The pressing temperature used was 125°C

The final panel thickness was 51 mm.

15,20

10, 15

6.5, 10

The effect of pressing pressure and time on some of the mechanical properties and glue bond quality of L VL from each of the two thicknesses were investigated. Hence, the experimental design of the study was a 2-factor factorial experiment in Completely Randomized Design (CRD) with three replicates.

The criteria below were used to evaluate the factors involved.

L Static bending (MOR) measured the strength of wooden beams, stringers angers and joists under bending loads. Specimen size: 51 x 51 x 610 mm. Rate of movable cross head: 2.54 mm/min.

9-1

System of loading: 3-point loading with a span of 558 mm.

2. Internal bond evaluated the strength and quality of glue bond between layered veneers. Specimen size: 51 x 51 x51mm

3. Water resistance evaluated the durability of glue bond under cycling boiling in water for 4 hours and drying in the oven for 20 hours at 6o0 c. A total of 4 cycles were conducted. Specimen size: 51 x 51 x 100 mm.

Note: Three specimens were used in each test per level.

RESULTS AND DISCUSSION

Table l shows the comparative roughness of 6.5 mm and l 0 mm veneers subjected to smoothness measurements using the laboratory shadow sectioning box instrument. The 10-min thick veneers exhibited greater and prominent depth of surface roughness of nosebar compression of 80/o, knife angle of 90° 00". The lathe checks were due to the wood's cross­grain feature and insufficient nosebar pressure (horizontal) gap between knife edge and nosebar. Because of the seemingly high load on the lathe in peeling the thicknesses, nose bar compression was not increased to a void breaking the machine. In contrast, the 6.5 mm thick veneers exhibited negligible lathe checks. Neither did they exhibit prominent depth of surface roughness.

Wood failure was observed opposite the point of loading in the static bending specimen tests for 6.5 mm and 10 mm L VLs at MOR I and MOR II. Wood checks were noted extending up to 52 mm long from the specimens' center.

92

The solid yemane wood gave a lower average MOR value (47.75 MPa) compared to the 6.5 and 10 mm LVLs (Table 2).

Table 3 presents the average MOR values for the 6.5 and 10 mm LVLs using ~ressing pressures of 15 and 20 kg/ cm and pressing time of 10 and 15

minutes, respectively. When the load was applied to the laminae edge, the MOR was lower because the area under stress was not homogenous. The said area was composed of the solid wood and the glucline. The gluelinc was the weakest point where the stress could be relieved.

Table 1. Comparative roughness values for 6.5 mm and 10 mm thick veneers subjected to smoothness test using the laboratory shadow section instrument (depth in mm)

6.5 mm VENEER

0.0010 0.0015 0.0004 0.0008 0.0012 0.0005 0.0035 0.0005 0.0007 0.0012 0.0008 0.0005

I 0-mm VENEERS

0.0035 0.0060 0.0050 0.0015 0.00"15 0.0055 0.0025 0.0018 0.0012 0.0012 0.0020 0.0025

Table 2. Average MOR values of solid wood and LVL from yemane species

MOR (MPa) SOLID WOOD 10 mm veneer L V L 6.5 veneer LVL

MOR I 1'v10R II MOR I MOR II

47.75 51.28 46.87 70.80 59.23

Note:

MOR -. load parallel to lamina MOR - load perpendicular to lamina

In spcci mens where the load was appl icd to the laminae face, the area u ndcr stress was the homogeneous part or the laminae (wood). This could be d uc to the absence of prominent lathe checks which were present in 10-mm veneers. La the checks, which arc in hcrcn t in veneering, always extend in ward from the underside or loose side or the veneer. They usually affect

93

the strength and durability of veneer produced by rotary cutting.

L VL produced from 6.5 mm veneers exhibited high internal bond values (Table 4). This reflected the advantage of quality peeling. This could also be attributed to'the smooth surface of the veneers and the a bscnce of la the checks. Deep la the checks in the I 0

Table 3. A vcrage MOR values from 6.5 mm and I 0 mm L VL using specific pressures of 15 and 20 kg/cm2 a ;1rf pressing times of IO and 15 minutes

SPECIFIC PRESSING MOR (MPa) MOR (MPa) PRESSttRE TIME (kg/cm ) (min) IO mm 6.5 mm IO mm 6.5 mm

15 IO 50.70 66.68 47.46 60.80

15 I5 54.32 66.58 52.66 60.40

20 IO 45.l I 73.05 28.24 56.I9

20 I5 55.0I 76.98 58.I5 6I.29

Table 4. Average internal bond (IB) values fro~ 6.5 mm and 10 mm L VL uging specific pressures of 15 and 20 kg/cm and pressing times of I 0 and I 5 minutes

SPECIFIC PRESSING IB (kPa) WOOD FAILURE(%)

PREssyRE TIME (kg/cm ) (min) 10 mm 6.5 mm IO mm 6.5 mm

15 IO 263.79 552.11 68.33 78.33

15 . 15 304.00 389.32 66.66 87.50

20 10 284.39 467.77 59.16 90.83

20 15 209.86 611.93 61.66 93.33

94

m.m L VL allowed the glue to penetrate deeper into the wood, thus producing starved glueline and ultimately poor glue bond.

In the cyclic boil test (IB), no delamination was observed in the glue lines. This was because phenol resorcinol formaldehyde was used, a

. boil-proof binder. It could also be due

to the heat introduced in the press platen (I 35°C), which accelerated glue setting in 10 to 15 minutes. The higher wood failure values in the 6.5 mm LVL could be attributed to the smoother surface and shallower la the checks present. Excessive roughness and checks cause poor quality glue bond and high sanding waste (Table 5) .

Table 5. Average wood failure values from cycyc boil test. of v~neer L VL u~ing specif-ic pressures of 15 and 20 kg/cm and prcssmg times of 15 mmutes

SPECIFIC PRESSING CYCLIC TEST WOOD FAILURE(%) PREssyRE TIME {kg/cm ) (min) 10 mm 6.5 mm

15 18 53.12 59.99

15 15 51.25 64.25

20 10 33.12 60.55

20 15 51.25 67.96

Table 6. ANOV A on the different properties of 6.5 mm LVL

SOURCE OF VARIATION

Specific pressure (A)

Pressing time (B)

Interaction (A x B)

Error

Total

DEGREES OF FREEDOM

8

I I

F-VALUES

MOR MOR

* 7.092 0.312 ns

0.385 ns 0.096 ns

0.411 ns 0.158 ns

IB

0.043ns

1.220 ns

* 5.696

Table 7. ANOV A on the different properties of 10 mm LVL

SOURCE OF VARIATION

Specific pressure (A)

Pressing time (B)

In tcraction (A x B)

Error

Total

Legend: MOR I MOR II 6.5 mm, 10 mm

ns

*

DEGREES OF F-VALUES FREEDOM

MOR MOR IB

* 7.092 1.298 ns 0.174 ns

0.385 ns 7.7424 * 0.015 ns

1 0.411 ns * 3.343 ns 4.412

8

11

- Modulus of rupture parallel to the glue line. - Modulus of rupture perpendicular to the glue line. - thickness of veneer used in the manufacture of

laminated veneer lumber (L VL) - not significant - significant

Table 8. ANOV A on wood failure in the cyclic boil test of 6.5 mm and 10 mm LVL

SOURCE OF VARIATION

Specific pressure (A)

Pressing time (B)

Interaction (A x B)

Error

Total

DEGREES OF FREEDOM

20

23

F-VALUES 10 mm 6.5 mm

* 5.775 .095 ns

* 4.376 .709 ns

.840 ns .052 ns

Legend: 6.5 mm, 10 mm - thickness of veneer used in the manufacture of laminated veneer lumber (L VL)

ns - not significant * - significant

95

96

The ANOV As (Tables 6-8) showed that specific pressure significantly affected MOR parallel to the laminae both in the 6.5 and 10 mm L VL. Only in the 10 mm L VL did pressing time significantly affect the MOR perpendicular to the laminae. The pressing pressure and time significantly influenced V/OOd failure in the cyclic boil test for 10-:mm L VL. The interaction of specific pressure and pressing time significantly affected the internal bond for 6.5 mm L VL.

CONCLUSIONS

• The 10 mm yemane veneers exhibit prominent lathe checks and rough surfaces caused by the cross-grain feature of the wood and insufficient nosebar pressure during peeling.

• MOR values of L VL are significantly higher than those of solid wood of the same species.

• The specific pressure significantly affects the MOR parallel to the laminae in 6.5 mm and 10 mm L VL.

REFERENCES

Pressing time also significantly affects the MOR perpendicular to the laminae in 10 mm L VL. Also, pressing pressure and pressing times significantly influence wood failure of the 10 mm laminae during the cyclic boil test. Interaction of pressing pressure and time significantly affects the internal bond of 6.5 mm L VL.

RECOMMEND A TIO NS

Acceptable quality LVL can be produced from yemane, with veneer thickness of 6.5 mm. Considering the combined effects of better strength and aesthetic features of L VL, a new study should be conducted which will cover the production of full-sized L VL for beams, economic feasibility /cost analysis of the product and product acceptance among the designers and builders.

L VL production using adhesives for the interior, i.e., urea formaldehyde and polyvinyl acetate, should be studied.

AMERICAN SOCIETY FOR TESTING AND MATERIALS. 1980. Methods of testing small clear specimens of timber. ASTM Designation D 143-52.

BEHLETZ, S.C. 1972. L VL: Laminated veneer lumber development and economics. For. Prod. J. 22(1): 18-26.

CHAN, F.D., E.N. SICAD and S.B. DAMASCO. 1988. Glue laminating characteristics of some Philippine wood species. FPRDI, Library.

ERICKSON, E.C.O. ·'1952. Mechanical properties of laminated modified wood. Forest Products Laboratory, U.S. Department of Agriculture. Forest Science Report No. R1639 (Revised).

KUNESH, R.H. 1978. Micro-lam: Structural laminate lumber. For. Prod. J. 29(7): 41-44.

97

LEI, Y. 1979. Fracture toughness of parallel-laminated veneer. For. Prod. J. 29(8): 28-31.

LYONS, B.E. 1987. Markets for structural use materials to 2010. For. Prod. J. 37(10): 6-62.

MOODY, R.C. and C.C. PETERS. 1972. Strength properties of rotary knife-cut laminated Southern pine. Forest Products Laboratory. Forest Service U.S. Department of Agriculture. FPL 178. 1-12.

SASAKI, H. 1981. Recent development with laminated wood products in Japan. XVII "IUFRO World Congress Proceedings," Division. 5.

SCHAFFER, E.L. 1972. Feasibility of producing a high yield laminated structural product. Forest Products Laboratory, Forest Service. U.S. Department of Agriculture. FPL 17 5. 1-18.

STUMP, J.P. et al. 1981. Laminated veneer lumber made from plantation. For. Prod. J. 31(4): 34-40.

YOUNGGUIST, J.A. et al. 1979. Production and marketing feasibility of parallcl­laminatcd veneer products. For. Prod. J. 29(8): 45-48.

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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.

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ABOUT THE COVER

Bagras (Eucalyptus deglupta Blume) is one of the fastest growing and promising plantation species for the production of pulp and paper, poles and sawn timber for various uses requiring moderately low strength. Small trees at the foreground are Moluccan sau [Paraserianthes f alcataria (L.) Nielsen) --- another fast-growing species. More on bagras on p. 60.