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Chapter 5DEVELOPMENT OF PARTICLEBOARD

5.1 INTRODUCTION

5.2 EXPERIMENTAL

5.2.1 Moulds and other accessories

5.2.2 Moulding procedure5.3 MOULDING OF PARTICLEBOARD

5.3.1 Particleboard from CNSL — hexa reactive mixture (Case 1)

a. Ingredients1. Binder

2. Filler

3. Additives

b. Formulation

c. Moulding parameters

I. Cure temperature2. Cure time

3. Curing pressure4. Resin content

5. P: F ratio

6. CNSL: P ratio

5.3.2 Particleboard from dry moulding powder (Case 2)

a. IngredientsI. Binder.

2. Fillers

3. Additives

b. Formulation


I. Resin come";

C hagter 5

2. P: F ratio

3. CNSL: P ratio

5.4 TESTING OF PARTICLEBOARD

a. Density

b. Moisture content

c. Water absorption

d. Tensile strength parallel to surface.

e. Tensile strength perpendicular to face (Internal bond strength)

f. Static bending tests

g. Compressibility5.5 RESULTS AND DISCUSSION

5.5.] Effect of moulding conditions and stoichiometry on theproperties of particleboard from CNSL-hexa reactive resin

(Case 1).

a. Effect of cure temperatureb. Effect of cure time

c. Effect of curing pressured. Effect of resin content

e. Effect of P: F ratio

f. Effect of CNSL: P ratio

5.5.2 Effect of moulding conditions and stoichiometry on theproperties of particleboard from CNSL-phenol-hexa copolymer

(Case 2)

a. Effect of resin content

b. Effect of P: F ratio

c. Effect of CNSL: P ratio

5.5.3 Effect of fillers

5.6 CONCLUSIONS

REFERENCES

Development of Particleboard

DEVELOPMENT OF PARTICLEBOARD

5.1 INTRODUCTION

Particleboards were first made during the l930’s. The wood particleboard

industry evolved due to shortage of timber and the need to dispose of largequantities of sawdust, planar shavings and to a lesser extent, mill residues and other

relatively homogeneous waste material produced by other wood industries. They

are widely used because they enable wood particles from relatively useless small

size and/or low grade timber to be transformed into useful large wooden panels (1).

Properties of the board depend among other things on the kind and amount

of binder used. When phenolic resins are used as binders particleboards arecharacterized by good physical and mechanical properties.

Particleboards are manufactured from particles of wood or otherlignocellulose material, formed and pressed together by the use of an organicbinder with the help of one or more of agents, such as heat, pressure, catalyst etc

(2). The basic material from which particleboards are made are (a) chips, which are

wood particles typically used in pulp manufacture (b) flakes, which aremechanically sliced wood particles (c) ribbons, wood particles of specific thickness

but varied length (d) shavings, thin, of short length and consisting of rupturedfibers (e) splinters, wood particles greater in length compared to width and (Dsawdust, comparable to particulate fillers but still possessing fibrous structure.Particleboard retains many of the properties of the wood from which it is made.

Particleboards for construction must have high strength and weatherresistance. The specific gravity of particleboard may be affected by productionparameters like chip form, and reactivity of the resin. Bond strength depends onchip form and binder content.

For special applications, the properties of the boards may be modified by the

addition of Chemical agents to provide additional properties such as highcompressive strength, water resistance, fire resistance and resistance to decay orinsect attack.

Chapter 5

The largest use of these panels is in the building industry, in which theyserve to cover up space — on walls, floors and ceilings. In this application, they may

serve various functions- heat insulation, sound insulation etc. They are also widely

used in the manufacture of fumiture, floor underlayment, cabinets, in homeconstruction and, a significant amount, in the manufacture of automobiles.

Sawdust is recommended as filler for its relatively low specific weight and

its abundance as a cheap byproduct in wood workshops. Agricultural wastes such

as rice husk, cotton husk, coconut husk etc. can be used for making particleboards

that would replace wood products (3-9).

Cost of these boards remains high due to the high cost of the synthetic resin.

Natural resin such as that based on CNSL can replace synthetic resins in board

manufacture. Application of CNSL as a full or partial replacement for synthetic

resin may be of interest in these days of diminishing petroleum resources.

In this study particleboards based on sawdust and CNSL were prepared and

the physical and mechanical properties determined for various synthesis andmoulding conditions.

5.2 EXPERIMENTAL

This section presents the experimental details of the developmental work on

particleboard made from CNSL. Two methods were adopted for the moulding of

particleboard.

a. Board made from CNSL- hexa reactive mixture

b. Board made from CNSL- phenol-hexa copolymer resin

Sections 5.2.1 and 5.2.2 discuss details of mould design and mouldingprocedure common to both cases. Specific details of each moulding procedure are

given in Sections 5.3.1 and 5.3.2.

5.2.1 Moulds and other accessories

The mold is made from mild steel and is a specially designed three piece

assembly. The bottom plate and the top plate are separated by a spacer/ framewhich holds the mold charge prior to molding. The top plate has a punch that

188


engages the frame. The punch when pressed by the platen compresses the powder

to about one third of its original thickness. The frame has a taper for easy release of

the moulded product. Photographs of the mould are given below. The mould is

designed for a board of size 300x 300 x 10 mm.

_;~.;...-2-;-1 2.2M

Fig. 5.1 Three piece mould for particleboard

5.2.2 Moulding procedure

The mould was heated to moulding temperature pn'or to molding. Themoulding composition was then charged. In order to facilitate easy release of the

molding cellophane sheets were kept on both sides of the mould charge. The mould

189

Chapter 5 g

with the molding composition was placed in a hydraulic press and the requiredpressure applied. Degassing was done at every five minutes to avoid blisters. After

curing, the mould was Opened and allowed to cool. The product was then taken outfrom the mould. A board with dimensions 300x300xl0 mm was obtained.

5.3 MOULDING OF PARTICLEBOARD

5.3.1 Particleboard from CNSL-hexa reactive mixture (Case 1).

a. IngredientsI. Binder

A reactive CNSL formaldehyde resin served as binder. CNSL and hexa were

heated at 100°C for 30 minutes in a beaker with continuous stirring. This resin was

used for moulding particleboard to study the effect of cure temperature, cure time,

curing pressure, resin content and P: F ratio. To study the effect of CNSL: P ratio,

resin was prepared by heating mixtures of CNSL, phenol and hexa in differentproportions.

Z. Filler

Sawdust collected from saw mills. Sawdust contains wood chips of varying

sizes from fine dust to pieces as long as 0.5 cm.

3. Additives

l. Magnesium oxide catalyst to speed up the curing reaction.

2. Dimethyl forrnamide as accelerator.

3. Zinc stearate as lubricant.

4. Naphthalene improve flow properties

b. FormulationSawdust 100Resin 5-25 %MgO 0.1- 0.5 %Zinc stearate l °/0Naphthalene 005- 0-25 %Dimethyl formamide 005- 0-25 %



Particleboards were made for different values of the following variables

1. Cure temperature

Keeping resin content constant at 15%, cure time 15 minutes, curingpressure 13.72 MPa, P: F ratio 112.9 and CNSL: P ratio 1:1, cure temperature wasvaried as 150. 160, 170, 180 and 190"c

2. Cure time

Keeping cure temperature constant at 150°C, resin content 15%, curingpressure13.72 MPa, P: F ratio 1:2.9 and CNSL: P ratio 1:1, cure time was varied as

5, 10, 15, 20 and 25 minutes.

3. Curing pressure

Keeping resin content constant at 15%, cure temperature 150°C, cure time 15

minutes, P: F ratio 1:2.9 and CNSL: P ratio 1:1, cure pressure was varied as 3.43,6.86, 10.78 and 13.72 MPa.

4. Resin content

Keeping cure temperature constant at 150°C, cure time 15 minutes, curingpressure 13.72 MPa, P: F ratio 112.9 and CNSL: P ratio 1:1, resin content wasvaried as 5, 10, 15, 20 and 25 phr

5. P: F ratio

Keeping resin content constant at 15%, cure temperature 1509C, cure time 15

minutes, curing pressure13.72 MPa, and CNSL: P ratio 1:1, P: F ratio was varied as1:1.1,1:1.7,1:2.3 and 1:2.96. CNSL: P ratio


minutes, curing pressure 13.72 MPa and P: F ratio 112.9. CNSL: P ratio was varied

as 100:0. 75:25, 50:50, 25:75 and 0:100.

Table 5.1 summarizes the moulding parameters maintained for particleboardmoulding.

ghapter 5? _ _ _ j _ _ 7Table 5.1

Moulding parameters used for particleboard with reactiveCNSL- hexa resin as binder

Moulding parameters3

MP8.

‘T {Cure 5 71 5 Curing 7 1 7 7 717 7 5 it 7. 5 711 t t Y Cqetlme re‘sure 1 Resm P:Fratio 1 CNSLP

150

160

170

180

190

_.|~— — _

15

1 151 151 151 15

13.72

13.72

13.72

13.72

112.9

112.9

112.9

112.9

112.9

emI()<1g; we .1 (mmutes) 1 P S 1 content \ 1 ratlo A1 11 15 1 ' 1 "1_.1_

100:0 N10010 1100:0 .100:0 W

100:0 VH _ 150

150

150

150

150

W 51015

20

l 7 25

13.72

13.72

13.72

13.72

13.72

7 15

1

112.9

112.9

112.9

112.9

112.9

100:0 5100:0100:0 ‘A

100;0 ,.100:0 4.[_150

150

150

150

E __. 15, 15

15

1 151

3.43

6.86

10.78

13.72

1 112.9

112.9

112.9

112.9

1500107 1

100:0 .10010 Y

100:0 11_. _1 150

150

150

150

150

* 15‘ 15A 151 15151. 1

13.72

13.72

13.72

13.72

13.72

112.9

112.9

112.9

112.9

112.9

:1 * " ‘ 1100:0

100:0 ‘1100:0 1100;0100:0 1,,,_ -9 11

150

150

150

150

717‘ 715151 151 1 5

T 13.72

13.72

13.72

13.72

1 112.9

112.3

111.7

111.1

100:0 ‘100:0 1100:0 110010 p

W 150

150

150

150

150

71515

15

15

1 1 5

13.72

13.72

13.72

13.72

13.72_ 1

1

‘ 1

112.9

112.9

112.9

112.9

112.9

100:0

75:25

50:50 125.75 1.01100 1

1 1 4


5.3.2 Particleboard from dry moulding powder (Case 2)

a. Ingredients

I. Binder.

A dry moulding powder composition based on phenol-CNSL-hexacopolymer was prepared. Details are given in Section 2.3

2. Fillers

l. Sawdust — collected from sawmills

2. Rice husk —collected from rice mills.

3. Additives

l. Magnesium oxide catalyst to speed up the curing reaction.2. Dimethyl formamide as accelerator.

Zinc stearate as lubricant.

:l°*5*’

Naphthalene improve flow properties.h. Formulation

Sawdust l0OResin 5-25 %M gO 0.1- 0.5%Zinc stearate l %Naphthalene 0.05- 0.25%Dimethyl formamide 0.05- 0.25%


l. Resin content

Keeping cure temperature constant at 1500C, cure time 15 minutes, curingpressure 13.72 MPa , P: F ratio 1:2!) and CNSL: P ratio 1:1, resin content was

varied as 5, 10, l5, 20 and 25 phr

¢'1s=P€¢r5___ _ _ ,2 _,2. P: F ratio


minutes, curing pressure 13.72 MPa_, and CNSL: P ratio 1:1, P: F ratio was varied1:1.1,1:1.7,1:2.3 and 112.9

3. CNSL: P ratio


minutes, curing pressure 13.72 MPa, P: F ratio 112.9 and CNSL: P ratio 1:1, CNSL:

P ratio was varied as 100:0, 75:25, 50:50, 25:75 and 0:100.Table 5.2

Moulding parameters used for moulding particleboard with

CNSl,- phenol-hexa resin as bin¢ler(M0u1ding temperature =1 500 C, cure

time = 15 minutes, Moulding pressure = 13.72 MPa)

7 liesff 7 P: F5113 T E"1~1si:i> 7content 1 1

, ,11 ratio 11, 5

L

1

11015 12025

l:2.9

1:2.9

1:2.9

1:2.9

1:2.9

7 '—'1

501750: 7 1

50;50150:5050I5O 11; 1; C 11,

1

1

1

15 115 1‘

1 151 5 ‘

1:2.9

112.3

111.7

1:1.1to 1

50:50 1

50:50i150:50 1

W:: _; : T ,1 5 115' 15 "

1 15 1151:2.9

112.9

l:2.9

1:2.9

l:2.9

1

1

, 1

160:0‘ 1

7512550:50 125275 1

0:100 1

g _ f _ g _ _ _ _ _ _ *D£’iZIfl’TQ]Z713£’_{Il"0I]3d!'ffC{8t?0fIf£i

5.4 TESTING OF PARTICLEBOARD

(AS PER IS 2380-1977 (10))

a. Density

The specimen used was of 7.5 cm wide and 15 cm long.

Density = mass of the specimen in gm / {length (cm) x width (cm) xthickness (cm)} g/cm‘;

b. Moisture content

The specimen used was of 7.5 cm wide and 15 cm long. It was then dried in

an oven at 103°C until the mass was constant. The moisture content, expressed as

percentage of oven dry mass, was calculated

Moisture content = (M, —M0)/MU X l00

M, --~ initial mass

M0 — oven dry mass

c. Water absorption

Test specimen used was 30 X 30 cm size. After conditioning the specimen

was weighed and the width, length and thickness measured. The specimen was then

submerged horizontally in clean water maintained at a temperature of 27°C. The

test specimens were separated by at least l5mm from each other and from thebottom and sides of the container. After a 24 hours submersion, the specimen was

suspended to drain for 10 minutes, at the end of which the excess water wasremoved and the specimen was immediately weighed. The amount of waterabsorbed was calculated from the increase in mass of the specimen and the water

absorption was expressed as percentage by mass alter conditioning.

d. Tensile strength parallel to the surface

Tensile strength in the parallel- to- face orientation is the resistance of aboard material when pulled apart parallel to its surface. Tensile strength parallel tothe surface is the load at the time of fracture divided by the cross sectional area(width x thickness) of the specimen.

Chapter 5_ ..~___ 7 _ Vl - length of specimen, mm

f. Static bending tests

Static bending tests determine both modulus of rupture (MOR) and modulus

of elasticity (MOE) of composites. Universal Testing Machine was used formeasuring these properties. Samples of 300 mm length, l0mm thickness and 50

mm width were used. The test was conducted at a crosshead speed of 6 mm/min

and loading span used was 240 mm.

I. Modulus of rupture (MOR)

Modulus of rupture is the ultimate bending stress of a material in flexure or

bending and it is frequently used in comparing one material to another.MOR = 3PL/2bd2.

MOR - Modulus of mpture, MPa.P - maximum bending load, N.L - length of span, mm, 24x thickness.b - width of specimen, mm.d - thickness of specimen, mm.

2. .M0dulus of elasticity (MOE)

Modulus of elasticity is determined from the slope of the straight line portion

ofthe load-deflection curve (P,/Y1).

MOE = P,L3/4bd3Y,

MOE - stiffness (apparent modulus of elasticity), MPa

Pl - load at proportion limit, NL - length of span, mm, 24x thickness.b - width of specimen, mmd - thickness of specimen, mmYl - centre deflection at proportional limit, mm

A typical load-deflection curve (particleboard moulded with sawdust andCNSL- phenol ~ hexa eopolymer resin with P: F ratio l:2.9, CNSL: P ratio l:l andresin content 25 %) is shown in Fig.5.3


Load- deflection curve

Load (N

,.._._..................,.......,......................-.._...-...........__..........-................--.....-..,. .............-...... .... l

120 +1

A 100so ;iso40 1‘ ~

.-\--..

20 <7

>--\-n

e0 i»._ , _ .__ .. e ..-.._..__._ 4 -.—‘L*—‘;=:O 0.2 0.4 0.6 0.8 1Stroke strain (°/i)

Fig. 5.4 Load deflection curve for particleboard

g. Compressibility

The test specimen used was 50 X 50 X 50 mm. The specimen was preparedby gluing five pieces of the board face to face. The size of the specimen wasmeasured correct to 0.1 mm and mass correct to 0.01 g. The test was carried out atroom temperature. The specimen was placed horizontally on the platform of themachine in flat position. The load was applied vertically on the specimen, at aconstant rate ofloading of 0.6 mm/minute.

Initially a load of l0 Kg was given on the specimen and taken as zeroposition. Then a load of 500 Kg was applied and this load was maintained for 10minutes. The defonnation was measured alter 10 minutes and was recorded as the

value of compressibility.

5.5 RESULTS AND DISCUSSION

Wood particles consist of cellulose, hemi cellulose, lignin and substanceslike resins, oils etc. Lignin is highly polymeric substance with a phenolic structure(ll). Most abundant chemical sites in the wood cell wall polymers are hydroxylgroups (l2)

The sawdust used is predominantly of rosewood. Components of rosewoodare geraniol, linalool_ nerol, lineole, terpinol, dipentene (13) in addition tocellulose, lignin etc.

Sawdust contain several reactive compounds and functional groups, so that"*"\"l1't from hvdrogen bond formation, a number of chemical reactions with phenol

§'1eP£"§___,_,lt_l_l,_s _llsfonnaldehyde condensate products can occur (2). The following types of reactionsare believed to occur (14). l) hydrogen bonds fomi between hydroxyl groups ofcellulose and phenolic resin, 2) crosslinking can take place between wood cell wall

hydroxyls and formaldehyde and 3) crosslinks take place between the hydroxylgroups on the same or different cellulose, hemi cellulose and lignin polymers. T0what extent these three interactions take place is a matter of conjecture.

This section presents the results of various studies relating to thedevelopment of particleboards. These results can be divided into two broadcategories.

a. Particleboard from CNSL- hexa reactive mixture (Case I) and

b. Particleboards flom dry moulding powder consisting of CNSI-phen0I- hexacopolymer (Case 2)

5.5.1. Effect of moulding conditions and stoichiometry on the properties ofparticleboard from CNSL-hexa reactive resin (Case 1)

a. Effect of cure temperature

To study the effect of cure temperature on the properties of particleboard,boards were made with resin content l5 phr, curing pressure 13.42 MPa, cure time15 minutes, P: F ratio 112.9 and CNSL: P ratio 100: 0 and varying curetemperatures.

Development of Particieboard

Propert es

-- at

4 ‘F k%ma—___.it %‘§ * ii *1O

== esereeefles — e e »—-—.—-e—*><~_ e - fix

150 160 170 180 190 200Cure temperature (OC)

-+— Density (Kg/m3) —-I—~ Moisture content (%) ——-A—— T.S(parallel)

-><- T.S(perpendicular) --x- Compressibility(mm)

Fig. 5.5 Variation of properties of the particleboard(Case 1) as a function of cure temperature

Fig. 5.5 shows the variation in density, moisture content, tensile strength

(parallel), tensile strength (perpendicular) and compressibility with curetemperature.

Density is almost constant when the cure temperature changes from 150 to190°C.

The effect of cure temperature on the moisture content of the resin is notsubstantial.

Tensile strength (parallel-to- face orientation) is the resistance of a board

material when pulled apart parallel to its surface. lt is the maximum load aspecimen can withstand when subjected to tensile loads in the direction of thelength. The board shows maximum tensile strength at 160°C. Tensile strength(parallel) is seen to slightly decrease at high cure temperature. This may be due to

Ch¢'~'r1*<'§____._ ,_ s C ___ __ slog g s U C ,__

degradation of wood fibers and also the negative effect on the properties of theresin binder.

Tensile strength perpendicular to face is a measure of the resistance of amaterial when pulled apart in the direction perpendicular to its surface. This test is

a true measure of the adhesive / bonding strength of the resin. The stress is applied

on a comparatively large area resulting in failure along a section parallel to both

faces. Particleboard shows maximum tensile strength (perpendicular) at 150°C.

Above this temperature bonding strength decreases. This can be due to possibledegradation of fiber or resin. At high temperatures water is eliminated betweencellulose hydroxyl groups to form ether bonds (ll). Ether bonds are not asamenable as hydroxyl groups to hydrogen bonding with polar phenolic resin. At

higher temperatures exudation of extractives to the surface as well as closure ofmicro pores in cell walls occurs, which reduces the number of active sites forbonding.

Compressibility is almost constant when the cure temperature changes from

150 to 180°C. From 180 to 1900C there is a sudden decrease in compressibility. It

is likely that above 180°C the resin becomes too rigid and the board reaches a state

of maximum compaction. Hence compressibility falls at this stage.

50 .....__.....-..--.........._-.._...._........_.......-.....__-._.....--._.._....-_.*.-...._.,_.-........_..._.._..-......_.....-.._....._......_....----..__.. - .. -

.

404? --*~ L i‘**-~_-. ?

_l~Ii

propert esI\J 00o o

' i1O\ '”“‘” .__._____ _4__. Q§150 160 170 180 190 200

Cure temperature (99)

-o- Water absorption (%) -—I— MOR(MPa)

Fig. 5.6 Variation of properties of the particleboard(Case 1) as a function of cure ‘|'DIr\r\n--—*


Fig. 5.6 shows the variation in water absorption and MOR with curetemperature.

At high curing temperatures water absorption decreases. At highertemperatures, a more crosslinked and impenetrable board results.

MOR is a measurement of composite board bending strength. MOR is the

ultimate bending stress of the material in bending and it is frequently used incomparing one material to another. Maximum MOR is obtained at 150°C which

matches the performance required by the Indian Standards. Further increase in cure

temperature decreases MOR.

1000 ‘._......._..._ ._ ....-.._...._ .. .~ ......_~._.........._..,_.u._...._...._..._..._.....Il if-':_-‘_7* 7 7;‘? _*_‘_—;-_‘e_ -_ *‘. i

lk/.,

MOE (MPa)

to A 0:o o QO 0 cs 0iU‘ ,;,__._.._._.,..?_,,._.-Z-._-i3 F

-XO70

1}\J0

u-Iooo

—§<0o

l\J

o

_~...,.__.».-_.,-.i~t--... ..i.A\-._.\~.-?,.”---..~.-ta-._ :¢..._..~.-.......i~.__., ‘Q,-,..--A--.i, t-i vi.“-_._.-._.,~,-._ ,--1,--...._ -m...--__~,.i.-,_.--i-_.. -..__-._~--?~

Cure temperature (OC)

Fig. 5.7 Variation of MOE of the particleboard(Case 1) as a function of cure temperature

Fig. 5.7 shows the variation in MOE with cure temperature. MOE ispractically unaffected by cure temperature.

b. Effect of cure time

To study the effect of cure time on the properties of particleboard,particleboards were made with resin content 15 phr, curing pressure 13.72 MPa,

¢!~3Pt@r§---___- - __ _ b _ - _ ,_.,,._._._.

cure temperature 150°C, P: F ratio l:2.9 and CNSL: P ratio I00: 0 and varying curetimes.

| 0 ,-*"~-"-¢'~—~""~"~*"""—“"'-"~'~*—"—'-'-“ '~'—"‘ '--‘“=‘~""-:=‘—‘;7-"—“"-""'*-'-'~'*—"=‘-'-"T¥ ~‘—""'*~-'—‘=*~I-=—‘-'-—-1'--=;—_-=-;—_==-.T_—;i_'.'.-_-“.1.-\-_==~=-;.~__-~».».-~..--.,~.--.@--...~»--~\~--.»-u--W.-~..-N».-¢~_»»-~_--W-»_.~,it 1it ii\ :

‘.8 H l***;~>l"*Hit ‘LK I....

Propert esA

4"-"'*"~ ~-» -A

‘* wee. _2 R i““%“%fiF““““*~1e~—————% ‘~ z;~e~=~¢——~——¢;~~———;xe——1——X0 _ _0 5 10 15 20 25 30

Cure time (minutes)

-.vh.,.=-.-;-.-_- _-~_—_-:--__

-+- Density (Kg/m3) ——-I—— Moisture content (%) —-A-— T.S(para|leI)

-><-- T.S(perpendicular) —-xe—— CompressibiIity(mm)

Fig. 5.8 Variation of properties of the particleboard(Case l) as a function of cure time

Fig. 5.8 shows the variation in density, moisture content, tensile strength(parallel), tensile strength (perpendicular) and compressibility with cure time.

Density is almost constant when the cure time varies between 5 and 25minutes.

Moisture adds to the weight and can also affect the environmental durability

of particleboards. Moisture content is almostconstant when the cure time increasesfrom 5 to l5 minutes. But there is a slight fall from 15 to 25 minutes. But such long

cure times can lead to degradation of pI'OpCI'liBS.

When the cure time increases tensile strength (parallel) increases up to about15 minutes. Tensile strength is almost constant with further increase in cure time.

Optimum cure time is about 15 minutes from the viewpoint of tensile strength(parallel).


Tensile strength (perpendicular) is found to be maximum when the cure time

is 15 minutes. Above this time degradation of resin or sawdust can occur whichdecreases the bonding strength. When the cure time is about 15 minutes the boardshows acceptable values. l 5 minutes are seen to be the optimum cure time.

Comprcssibility decreases when the cure time increases from 5 to 15minutes. Thereafter there is little change in compressibility. At this point theparticles were in their most compact form. Therefore no further decrease in volume

could take place.

60 - ... .. .. ..50.

40 1‘

Propert esIx) 00O O

10 € 1Q _ . _......_.....__...._._.-.-__..-.-._...._..-._.-..- ._......_..--_.,,.__....._..-__..-0 5 10 15 20 25 30

Cure time (minutes)

-¢— Water absorption (%) —-I—— MOR(MPa)

Fig. 5.9 Variation of properties of the particleboard(Case 1) as a function of cure time.

Water absorption decreases when the cure time increases from 5 to 25minutes.

Chan"-’1§__ i _ _ as _ s ____.,,_,_.

There is an increase in MOR when the cure time increases from 5 to 15minutes. Further increase in cure time results in reduction of MOR. A cure time 10

minutes is sufficient to get a board with a standard value of MOR.1090 I800

li l600 1 3i

(MPa)

400 j

MOE

200

0 s_.__.__..__.__.._.___..,_-_.__.__. __.__.-__.____..__...__.._._____.._.. .._.______.__.____....____.._.__.__,._..__..._.__..__...__10 5 10 15 20 25 30Cure time (minutes)

Fig. 5.10 Variation of MOE of the particleboard(Case 1) as a function of cure time

Fig. 5.10 shows the variation in MOE with cure time. MOE is maximum ataround 15 minutes.

c. Effect of curing pressure

Particleboards were moulded with cure temperature 150°C. cure time l5

minutes, resin content 15 phr. P: F ratio l:2.9, CNSL: P ratio 100:0 and varying

curing pressures viz. 3.43, 6.86, 10.78 and 13.72 MPa. The boards made at 3.43,6.86 and l0.78 showed very low bonding strength and the results are notreproduced here. Hence a maximum pressure of 13.72 MPa is needed.

Development of Parficleboard

d. Effect of resin content

To study the effect of resin content on the properties of particleboard,particleboards were moulded with curing pressure 13.72 MPa, cure time l5minutes, cure temperature 150°C, P: F ratio l:2.9 and CNSL: P ratio 100: 0 and

varying resin contents

.......». -1,........\....~\,-......... ..».\...........--...\, .-..... .....~\.......-..4-............ |IAI\ ...,.........-._.--.~\,. - Mt.-t,.. ...\,...~w .-......--~..~.--..... ,- ..\...,.........

_.LPO

i

10 M

;""'-_-'--F_‘

Prope

-A O3

I188

;; -~I"'fl {'2 it X’ eO 5 10 15 20 25 30

Res in come nt (%)

-4- Density (Kg/m3) ——I—— Moisture content (%)_-¢- T.S(paral|el) ~—a<-— T.S(perpendicuIar)-x— Cornpressibility(mm)

Fig. 5.11 Variation of properties of the particleboard(Case l) as a function of resin content

Fig. 5. ll shows the variation in density, moisture content, tensile strength

(parallel), tensile strength (perpendicular) and compressibility with cure time.

A higher resin content increases the average density of the board. A higher

density leads to a higher strength. But it is undesirable in particleboards because

panels become inconveniently heavy. Although many other properties improvewith density practical difficulties arise because of the inability of nails to pearcedense particleboards. On the other hand a low density is meaningful only ifmechanical and other properties are satisfactory. There is a small increase indensity as the resin content increases from 5 to 25%. The resin content has to be

§l'“P"-1'5 , _ _ - _ KKKKKKKKKKK - _ _

decided based on changes in properties which are more critical and more sensitiveto resin content.

There is a gradual decrease in moisture content as the resin content increases

from 5 to 25%. The fall in moisture content with increase resin content can be

attributed to many reasons. The higher exothermic temperature reached at higherresin content can lead to a more effective expulsion of moisture. Further, a more

effective encapsulation/ bonding of the fibers at higher resin content can preventsubsequent moisture absorption by the particleboard.

There is a gradual increase in tensile strength (parallel) as the resin content

increases. A stronger bonding of the fibers can be expected at higher resin contents.

There is a sudden increase in tensile strength (perpendicular) as the resincontent increases from 5 to 15%. When the resin content is more than l5 % the

board shows tensile strength values as specified by the standards. Below 15% the

resin content is not sufficient to give cohesion between the fibers.

There is hardly any dependence of compressibility on resin content.

50 it K .

Proper esN 00 -hO O O

_, -W-I“

it

it

10 if

‘-‘.

Z. §2-.__--_-_--_" _---1-_-_.-__\-__--1-._.___..__-.-.1-.1.____.1-§-_-___».1_._-~__\.;-____--._- 7‘-_r.-ah;-._ —_ ~_-- _ -._ _ _ ___ _ _ _0 5 10 15 20 25 30

Resin content (%)

-0- Water absorption (%) -—I- MOR(MPa)

Fig. 5.12 Variation of properties Of the particleboard(Case 1) as a function of resin content

Fig. 5.12 shows the variation of water absorption and MOR with resin content..


Water absorption decreases gradually as the resin content increases from 5 to

25%. Encapsulationf binding of the fiber by the resin and closing ofthe capillarieswithin the board as the resin content increases can be the reason for this..

MOR increases gradually as the resin content increases from 5 to 25%.When the resin content is about 10% the board shows commercially acceptablevalues.

3900 V2“

2500 P

O00

MOE (MPa)to

500

1-‘

1000 l

500 ;I t ;i :O lL....i...._...._..,...___i......_.,...__...~._,....__.~__..-.-._......_., ,..__.-.,_,.-__....---__..._._...-_~...._.,..__.\..-__. _.-..__.... ,---...._._....._......_.\..---¢O 5 10 15 20 25 30

Resin conte nt (%)

Fig. 5.13 Variation of MOE of the particleboard(Case 1) as a function of resin content

Fig. 5.13 shows the variation of MOE of the particleboard as a function ofresin content. There is a sudden increase in MOI-Z as the resin content increases

from J5 to 20%. Above 20% MOE is almost constant. Around 20% resin content is

necessary to meet the commercial specifications as far as M OE is concerned.

Chapter 5_______** f — i i —*

e‘. Effect of P: F ratio

‘O 1‘----...~...Q--w-...._\ .-..-v..-.-.4-,.~..--._\-,_.---,.~’».-._--.»-,----..<-u-_--.~--~__~_-..-..~._\.__-~---_~.~_-»..-,.~-..-_»--».~--~_-_~_-.~-~-_»¢--c._»-_---»--w--a.-....._,.._w.. --.-_-.\I1 98 __,_.,-0'- 6 ~3

Propert es

1 1 i4 3‘ _ n____‘-__,<_e _ ee i=4‘0 >~ eie”01:00.9 01:01.3 01:01.8 01:02.2 01:02.6 01:03.1

P:F ratio

s-+- Density (Kg/m3) —-I-— Moisture content (%) ——A-—— T.S(paralleI)

-><-- T.S(perpendicuIar) -—>x-- C0mpressibility(mm)

Fig. 5.14 Variation of properties of the particleboard(Case 1) as a function of P: F ratio


(parallel), tensile strength (perpendicular) and compressibility with P:F ratio.

Density is almost constant when the formaldehyde content changes froml:l.l to it 2.9.

Moisture content is almost constant when the formaldehyde content increases

from l:l.l to 1: 2.9. The slight increase indicated may be due to greater presence of

CH2OH groups as the formaldehyde proportion increases.

Tensile strength (parallel) increases as formaldehyde content in¢;ea5¢5_

Bonding between the fibers is good when a resin containing higher >mm....... Ar

_ _ _ _ _ DevelopnferttgofParficleboard

formaldehyde is used. At high formaldehyde content the degree of crosslinking ishigh.

Particleboard prepared from resin containing higher amounts of formaldehyde

showed slightly improved bonding strength. Resin with high formaldehyde content

may be more reactive towards fibers apart from being more crosslinkable.

Compressibility decreases as formaldehyde content increases. A higherdegree of crosslinking and binding between sawdust and resin may be responsiblefor this.

50 3 .............. M g 4_ —01; »— a ~ k ‘P '._ §1

I195coc>

ti i‘ 5l iii ._._?— II a elf ’r j_ra_fi_._10 Q-=-#"“““" =

propef\)o

it §1 2.1 1‘» —— _—__—_— — av‘ —_ _—_—_- _-,7-_— — — -.--___.~...____-~....-..,---_i..-.-.~ ~— —_— — __—=,— _ — -—_~~, — __»-_'---i_.,..~-_i._-..-..i._..~---i..-Q“?-a

01:00.9 01201.3 01:01.8 01102.2 01:02.6 01103.1P:F ratio

—o—- Water absorption (%) ——I-—- MOR(MPa)


There is not much variation in water absorption as the formaldehydecontent changes.

MOR increases gradually as the formaldehyde content increases. Resins with

P: F ratio 1: 1.7 and less shows values higher than that required by the standard.

C_liagte[5_ _ *_ 0 j j 0 i _ i 0

MOE (mm)

Fig.

1000 .m_.M-.~._ .~._-...~.-W_,.~w_e.‘._.~.,._-r._»._v._M_oaa; - to 1 <1 o _\'¢"-1%"'\"'--\~v~fln1o\1-‘800 0 _ .it ks it600 ;400 1200 J

01200.9 01201.3 01101.8 01102.2 01102.6 01103.1P:F ratio

5.16 Variation of MOE of the particleboard(Case 1) as a function of P: F ratio

Fig. 5.16 shows the variation in MOE with P: F ratio. MOE increases only

slightly as formaldehyde content increases.

i _ _ f W _ y_ fDpevelopment0fyPaiftt'cIeboard

f. Effect of CNSL: P ratio

16 W ..-_.t..~.-._~_..-_e~e....c.._.~..t-..-..._ ._ - ... _14 t

12 ,t10 7"sas _ -48 - + §6t i4!2 E K _*— if i K hi-P}?****‘*;-i->"* ——i—**r*

propert es

ti

_ “:_-F__ _ ___ _ t 7“; ___ _:y_____ _0 _~:o_ eta.-— _.— -can 1: J -—. _~_~. --~_-.~._~_o~o ~ ~=-_——_--.1-J_;-upO 25 50 75 100

CNSL content (%)

it

-+— Density (Kg/m3) -1- Moisture content (%) —a-— T.S(paralIel)

--><-— T.S(perpendicuIar) —x-- C0mpressibility(mm)

Fig. 5.17 Variation of properties of the particleboa rd(Case 1) as a function of CNSL content

Fig. 5.17 shows the variation in density, moisture content, tensile strength(parallel), tensile strength (perpendicular) and compressibility with CNSL: P ratio.

Density remains almost constant as CNSL content increases.

Moisture content increases initially as CNSL content increases.

Tensile strength (parallel) decreases sharply as CNSL content increases up to

50%. This is due to the lower reactivity of CNSL due to the presence of the longside chain ot‘CNSL.

As the CNSL content increases bonding strength decreases. CNSL has a10112 side chain, which induces a plasticizing action that can improve the impact

Cha_pter§ _ _ i _ _properties but decrease the bonding strength compared to phenol. Crude CNSL alsocontains constituents that may not react with formaldehyde. IS specifiction fortensile strength (perpendicular) is a minimum of 0.8 MPa. Even at 50% CNSL

there is a bonding strength of 0.8 MPa for the board. So a particleboard with goodbonding strength can be obtained even afier replacing 50% of phenol by CNSL.

Compressibility is seen to increase drastically with CNSL content. Thepresence of the substituted phenol in CNSL leads to less effective binding andconsolidation. Hence compressibility increases with CNSL content. However at50% CNSL content compressibility is not excessively high.

E:40 *t— e_ - —~-~+ ~ +ffi%__

Proprt esM ooO O

atIt tiit i.l1 fi* ‘ it* a J10 ;

0 ; __ To -__. _ _ i _._ u-.. u ....__ cO 25 50 75 100CNSL content (%)

—o— Water absorption (%) —I— MOR(MPa)

Fig. 5.18 Variation of properties of the particleboard(Case 1) as a function of CNSL content

MOR decreases as CNSL content increases.

There is slight decrease in water absorption with increase in resin content

beyond 50%. The hydrophobicity of CNSL can be the reason behind this.

_ 1 _ c c : ; : : i o ; A 1 _ _ : 1 _ _ _ t _D¢v5={vr3w¢"3 Pffiflffiviclzeerfi

MOE (MPa)

Fig.

‘ ........... t---\--_~.-.-----_~~ .~.~-........~»- ---.~----_~.~_.~,_~,.-av‘-_~ ~\- -.~\\--».-__h-,-\-.._--.-.¢-»-.\---.¢¢~- . .__..\.-.--_..w-- .- Q.» .- . .-W ..w.-.--_.,.'5r ———~e ~ 11-e._ ,t 2

800 @;\ t= lt Il I

600 it

».~._...»~.

J400 a

200\Q c _ _ _ _ _0 25 50 75 100

CNSL content (%)

5.19 Variation of MOE of the particleboard(Case I) as a function of CNSL content

MOP. decreases as CNSL content increases. At 50% CNSL there is only asmall change in MOE. Hence half of phenol can be effectively replaced by CNSL.

Chapter 5

5.5.2 Effect of moulding conditions and stoichiometry on the properties ofparticleboards from dry moulding powder consisting of CNSl-phenol- hexacopolymer (Case 2)a. Effect of resin content

14~

Propertes.-L _\

O N -A O5 CD O N

I _I .. .—1*"U\.‘ ‘ 1.1. :4.//~*~<t__: .0 5 10 15 20 25 30

'M n up Resin content (%)-0- Density (Kg/m3) -1- Moisture content (%) —a— T.S(paralle|)

—><— T.S(perpendicular) —x—- Compressibility(mm)

Fig. 5.20 Variation of properties of the particleboard(Case 2) as a function of resin content

Fig. 5.20 shows the variation of density, moisture content, tensile strength

(parallel), tensile strength (perpendicular) and compressibility with resin content.

Density is almost constant when resin content varies from 5-25%.

There is a drastic fall in moisture content when the resin content varies from

10- 15%. In the higher range of resin content, 15-25%, it is almost constant.

There is an increase in tensile strength (parallel) as the resin contentincreases from 5 to 25%. As the resin content increases bonding between the filler

particles becomes stronger and hence tensile strength increases. The values aremaximum at about 25%.

Tensile strength (perpendicular) increases steadily as the resin contentincreases. When the resin content is about 10 phr particleboard shows tensile

2l6

Development of fqrticleboard

strength values greater than 0.8 MPa specified by the IS 2380 (1977). It can beinferred that beyond 10% resin content a cohesive composite structure isestablished. At this stage a continuous bond cementing individual fibers togetherappears to have developed. The percentage binder required is less in this casecompared to Casel.

Compressibility decreases slightly as the resin content increases. As the

bonding between the filler particles increases the free space available decreases and

hence compressibility decreases.

*0 .~.-..¢...-----~-_-_....-_-~ -w .- QC MR ....,.....\-....,,.-M.-...-.1.“-.-..w-..,..-.,-......

40 t

rtesPropI\J COO Q

11 1ll10 ll _._ ~-._~_,* __._.

iF .$..,._.._..._.._..._...,_..s_....__..._.._..._~._..._.._..._,~__...._..-._..._..-,_.._.._...-_.._..__...__..._, ._.,_..-_.,.._. .._..~_>0 5 10 15 20 25 30Resin content (%)

-o- Water absorption (%) e-n-- MOR(MPa)

Fig. 5.21 Variation of properties of the particleboard(Case 2) as a function of resin content

Fig. 5.2] shows the variation in water absorption and MOR with resincontent.

There is a sudden increase in MOR when the resin content increases from l0

to 15 phr. When the resin content is more than l0 phr particleboard shows values

greater than the minimum value l 1 MPa specified by the standard. This behaviour

is similar to the case of tensile strength (perpendicular). Both graphs suggest asudden improvement in the performance of the board beyond l0% resin content.However MOR values given in the specification is reached at as low a resin content

Chapter5* i j i j _ 4 ias 10%. Hence the board shows a superior MOR compared to conventionalsamples.

There is a sudden decrease in water absorption when the resin content

increases from 10 tol5%. As the resin content increases there is better bondingbetween wood fibers. This provides less pathways for water to penetrate thecomposite material. It is possible that at l5% resin content, there is effectiveencapsulation of the fibers and closing of the capillaries.

l

l1 _. !4_ —y s 1-44000 ¢

MOE(MPmN) OJ

000 31

000 é1

l

l

l

1000 "l

l

1 .i Ei

0 5 10 15 20 25 30Resin content (%)

Fig. 5.22 Variation of MOE of the particleboard(Case 2) as a function of resin content

There is gradual increase in MOE as the resin content increases up to 15 phr.

Above 15 phr resin content MOE is almost constant.

_ _ _ U Qweiopiizeiir of Particieboard

b. Effect of P: F ratio

10 Ti /8y k_#_¥_, +*6 .I 2 .-ya.-...w.,i.“..,.~,..-.._..~..,--_ ....-wt. .,..._._,~v.w-..........,.v-.»-_._ M -~ _-.,,.,..~-- ...»~v.\,..v_..~_»A~.,v.. ..v..,...... ._._¢\~w,.~,- ..“~~-V

._.“ -

propert'e

XQ

S

4 =1 ~-~~ ~~2 1 es: e I0% s fie: 3:01:00.9 01:01.3 01:01.8 01:02.2 01:02.6 01:03.1

P:Fratio

-0- Density (Kg/m3) —|— Moisture content (%) -;- T.S(paraIleI)

-+<— T.S(perpendicular) -—~>x— Compressibitity(mm)



(parallel), tensile strength (perpendicular) and compressibility with P: F ratio.

There is some decrease in density as the formaldehyde content increases.

There is greater reduction in weight as the formaldehyde content increases due toelimination of more molecules of water of condensation.

Moisture content decreases slightly as the formaldehyde content increases.

There is a gradual increase in tensile strength (parallel) as the formaldehyde

content increases. A more crosslinked and compact structure of the resin may be

responsible for this. A higher formaldehyde content may lead to more effectiveinteraction with wood fibers because of higher methylol content.

¢!*“Pf@*5_ on 0 _

A greater tensile strength (perpendicular) is observed as the formaldehyde

content goes up. This is in agreement with the observations made earlier. At higher

formaldehyde content the resin has higher adhesive strength and cements the wood

fibers more effectively. Higher formaldehyde content leads to a higher content of

methylol groups and a greater degree of crosslinking.

Compressibility decreases as the formaldehyde increased up to about 1:2.3.There are fewer number of voids in the composite material as the formaldehydecontent goes up.

50 _ _ - ;40l :4 ;‘_ EU w — ~~ » we

rtes00O

Eii ___:__ __.__~a~10‘ I

prope|\)C)

1 i1 ,01:00.9 01:01.3 01:01.8 01:02.2 01:02.6 01:03.1

P:F ratio

-4- Water absorption (%) ——I— MOR(MPa)


Fig. 5.24 shows the variation in water absorption and MOR with P:F ratio.

There is no variation in water absorption as the formaldehyde content

changes.

There is a steady increase in MOR as the formaldehyde content increases.The MOR values satisfying the Indian Standards is reached at a P: F ratio of aboutl:l.7.

0 a,__,__::,,;,,___::::__:c_: _ J?@P€'QPI'?§"£K°)f*I“!"?P'€bP¢?'4

5000 0 _l‘ E1 11 24000O00 ;'

MOE (MPa)ro onooo

11

l1

11000 1;0 c_.______. 0,, ,0 0, ____c ,0 0 ._-_;.a.._..,.a_;.ae;~i_0, 5 _.a._.._.._.__.._

01:00.9 01:01.3 01:01.8 01:02.2 01:02.6 01:03.1P:Fratio

Fig. 5.25 Variation of MOE of the particleboard(Case 2) as a function of P: F ratio

Fig. 5.25 shows the variation in MOE with P: F ratio. MOE increases as

the formaldehyde content increases. At the lowermost formaldehyde contentstudied namely l:l.l molecules of the condensate tends to be large. At such lowformaldehyde content, methylol groups are fewer. On crosslinking a less stiffnetwork structure is established because of lower methylol functionality. But -at

high formaldehyde content (> l:2.3) a high functionality leads to a highlycrosslinked network.

C liapter 5

c. Effect of CNSL: P ratio

‘ 6 . ........................... ._....,<~.-.~w“». ....... ._ ........... ---..\.--».~ .... .-wv-.~-\\-.\-0....-._. ......... ..,,_,,,__. ___________ _,__~_~,_____ _______ __,_,,__.,____________ ___ ,____ _14 ill tl 112; “.3 10 ‘i .8 1 ‘

Propert

6‘) .3 Lei? i" s ;_ 30 20 40 60 80 100

CNSL content (%)

_¢- Density (Kg/m3) —|- Moisture content (%) _;- T.S(paraIlel)—a<-— T.S(perpendicular) -ax—- Compressibility(mm)

Fig. 5.26 Variation of properties of the particleboard(Case 2) as a function of CNSL: P ratio


(parallel), tensile strength (perpendicular) and compressibility with CNSL: P ratio.

There is only a very small change in density as the CNSL content increases.

Side chain of cardanol or other phenolic compounds in CNSL can lead to loosepacking of the chain. The adhesive properties tend to be poorer in this case. Hence

a fall in density can be expected.

Moisture content decreases as CNSL content increases. A higher percentage

of CNSL leads to a higher percentages of aliphatic compounds in the form of sidechain of the CNSL molecule. CNSL is more hydrophobic than phenol.

Tensile strength (parallel) decreases gradually as CNSL content increases.Particleboard based on pure CNSL- fomialdehyde copolymer is about half asstrong as that based on pure phen0l- formaldehyde copolymer. The lower reactivityof C NSL, steric hindrance caused by side chain etc. can lead to a polymer of lowerstrength and binding Dower.

ff _ L __ __ i _ i _ _ _ g _ Deveflogmentg0fPa§ticleb0f1rdg

The perpendicular tensile strength or bonding strength of the resin is notseriously affected on addition of upto 20% of CNSL. Beyond 20% the strength falls

drastically. Tensile strength (perpendicular) is higher than the value specified byIndian Standards when the CNSL content is less than about 50%. Consideri.ng thelow cost of CNSL and its renewable nature use of CNSL can be a worthwhile

proposition.

Compressibility increases marginally with CNSL content.

_..-.~».~--..---, - _. wu ~.._.-~,»--- w- - N -~»- w vv

Propert es-» M 0.) -b 01O CJ O O O O

r—"-?-—' -— —-—q--—

&' ,7 ___~-** i7__'f 7 V._, ‘jg!i e —+ 1 a '7"_;:_ ;'_ :_— ' '__~.-in-map ' ~: ~ ;'— ' ;1 ~;_—_r -_~._-_-_ _"_:' _>-_-_ ' —__—' ' ;_— _ ~ i—i;-_--_-_—_— if ———<_— —;—_ 7 7 "'_'_'_'é0 25 50 75 100

CNSL content (%)

-0- MOR(MPa) —a-- Water absorption (%)

Fig. 5.27 Variation of properties of the particleboard(Case 2) as a function of CNSL: P ratio

Fig. 5.27 shows the variation in water absorption and MOR with CNSL: Pratio.

There is not much change in water absorption as CNSL content changes. The

slightly higher water absorption indicated at higher CNSL contents may be caused

by slower and possibly incomplete reaction between hexa and C NSL.

There is a small decrease in MOR as CNSL content increases. CNSL givessome flexibility to the resin.

_(_I'hapter

4000 0' é’~ 000 5

.~.~ U».-..-‘Q-,--._¢

Pa(.40

000 ‘ i= l5 22

MOE MIx)

i1000 § §5

?O 25 50 75 100CNSL conte nt (%)

Fig. 5.28 Variation of MOE of the particleboard(Case 2) as a function of CNSL: P ratio

Fig. 5.28 shows the variation in MOE with CNSL: P ratio. MOE shows a

slight fall on addition of more and more CNSL. Here also the lower modulus may

be the result of a more flexible resin resulting from the presence of CNSL.

5.5.3 Effect of fillers

Table 5.3 shows comparison of properties of particleboards made fromCNSL —phenol- hexa resin using different fillers (resin content — l5 phr, cure time

15 minutes, cure pressure 13."/2MPa, cure temperature 150°C, CNSL/P — 50/50, P:

F l:2.9). Board made from rice husk has comparable values of tensile strength(perpendicular). Rice husk leads to a board of much lower density than that madefrom sawdust. Rice husk board has a much lower tensile strength (parallel) while

tensile strength (perpendicular) is only marginally less. MOE and MOR are bothvery low compared to sawdust board.

I 243, 8.88 I 16.4

_ _ _ _ _ _ _ _ : : : : i ; : __ __ _ _ _ _ _ _ _ _ _ 6_D?'{"{"F3"!‘3i't_°[Iiaftfcieliofirq

Table 5.3

Comparison of properties of particleboards made from CNSL ~phenol- hexaresin using different fillers (resin content — 15 phr, cure time 15 minutes, cure

pressure l3.72MPa, cure temperature 150°C, PIF - 50/50)

I T? 5 T 5 IiMOi;t;;e: lwmer "l"en*silefiI 5 Lleintsilei T I I I ; J I 1 5I Density’; I IStren;;thI Strength I MOR n MOE (CompresI Finer 1‘ Content abSOrpti0nParallel InIPerpendicularI(MPa)I(MPa)I sibilitys I I

'oO“

L») /-BQ\ya

T5\-/

_._.1

‘gm/ccI _______ _l I 6 _I7(l\T/l'?ai)__II:s~(!Y,[l__)al__;II._ II_ _,J__,_,,,_,,_ ____, _ .. ,,_ ,__*I I\ lIs6.w6ustI .23 10 A 10.8 I 1.2 I 36.9 H4156 L 0.98II ___ ___ *' I

II

II

II

II

II

I

II

_ _ m __ , — Z 77 7 4 ’ ’ 7 7’ _—y-,7" 7’ L,’ I-j 4- ; 2- 1 1Rm ‘ . I .92 I 695 1. 3.066(___l19S§(_)___*____%_%*__ __)_§____sL__6__L I‘

4‘ 5 *II

I

I

©

1 6%II

II

II

I_ I

N Im L 4_

I

I

s='> I@ II

oo M

I_ _ _ _ _ _ i l I 7_ t t 7 7 7 _ _ _ _ _ __ i : f Z ii-if _— _% 7—

Table 5.4 shows comparison of properties of particleboards made fromCNSL —phenol- hexa resin and CNSL-hexa resin (resin content — 15 phr, cure time

15 minutes, cure pressure l3.72MPa, cure temperature 1500C, CNSL/P — 50/50, P:

F l:2.9). Particleboard moulded from CNSL-phenol-hexa resin shows lowermoisture content, water absorption and compressibility and higher tensile strength

(parallel), tensile strength (perpendicular), MOR and MOE compared toparticleboard moulded using CNSL~hexa resin.

§_'ha_ptef5_*___ __* if pg

Table 5.4

Comparison of properties of particleboards made from CNSL —phenol- hexa

resin and CNSL-hexa resin (resin content — I5 phr, cure time 15 minutes, curepress e 13.72MPa, cure temperature 150°C P/F — 50/50)ur ,

7 5 5* 5 "5 5 5 ‘15 55 5 TV 5 T T : .: 5:‘ 5 H 5; 55 5"; : 5 T5 *5 '5 *5 —~ . 4 Tensile l Tensile W 1 1‘ 11

R _. Densityc t t1‘b ti Strength Strength MORMOE1Compres‘Moisturei Water 1

85'“ 1 m/‘ . °“ 6“ 6* 5°’? °“ Pa 111 Perpendicular(MPa)i(MPa) sibilityg (.C1 (0/0) 1 (0/O) T3 C- - - - - - .l~.(MP.a)“ -<MP==1-- g

J;

1 CNSH)" 116 it 32 10 ‘ 108 1 16 3694156 1.803hexa Q1: ' ' 14 1 L L1: ' 1 ' 1 ' 1 11 W 1 1 1 1 1 1CNSL-hexa 1.111 8 1 40 ‘A 4 0.8 118.92 774 1.983J1 1‘ i1 _ _ _ u. _ _ _ Hi 1 ‘, , i

5.6 CONCLUSIONS

The mould design and the moulding procedure adopted for particleboardmoulding by both the methods (Case l and Case 2) are found to be effective. This

can be a starting point for a moulding process to make larger mouldings.

The cure temperatures studied (I50, I60, 170, 180 and 190°C) are found to

affect the properties of the board only marginally. The overall picture favors a cure

temperature of l500C. Most properties are optimal at about 15 minutes cure time.The resin content affects the tensile strength (perpendicular) drastically. It shows

acceptable values at any resin content beyond 15% when a binder consisting of areactive mixture of CNSL and hexa is used. A P: F ratio of l: 2.9 is required to give

sufficiently high values of bonding strength. There is a slow but steady increase in

tensile strength (perpendicular) as the formaldehyde content increases. The presenceof CNSL lowers the tensile strength values. But about 50% CNSL can be used to

replace phenol to give a board with acceptably high values of bonding strength. ln

general, CNSL content increases the compressibility of the board.

A resin content of 10% gives sufficiently high values of bonding strengthand acceptable values of water absorption when the powdered resin resulting from

_ Development of Partieleboard

the condensation of CNSL, phenol and liexa is used. Both MOR and MOE reach a

plateau at 15% resin content. The P: F ratio has very little effect on the bondingstrength which is uniformly high. Increasing CNSL content leads to a board oflower tensile strength but the bonding strength is still high upto 50% CNSL content

in a mixture of CNSL and phenol used for the binder.

Chapter, 5

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TS: 840 (1964)

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B. English, J.A. Youngquist and A.M. Krzysik, Lingnocellulosic Composites,1n: R.D. Gilbert Ed. Cellulosic Polymers, Blends and Composites, New York,

Hanser Publishers, 1 I5-130, 1994, Ch. 6

novel applications of cashew nut shell liquid in the...

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