UNIVERSITI PUTRA MALAYSIA

GLUING PERFORMANCE OF MIXED HARDWOOD TABLETOP

SRI SUTOPO

FH 1991 3

  

UNIVERSITI PUTRA MALAYSIA

GLUING PERFORMANCE OF MIXED HARDWOOD TABLETOP

SRI SUTOPO

FH 1991 3

APPROVAL SHEET

Name of Candidate SRI SUT OPO

Title of Project GLUING PERFORMANCE OF MIXED HARDWOOD T ABLE-T OP

Approved by

ZIN JUSOH

.. �.�\� ... �\.:. ��� ....... . Assoc. Prof. D�ZALI ABDUL KADER ( Coordinator , M.S. Wood I ndustries Technology

Programme )

Date

For my wife Yuli, my son Daru and my daughters

Putri and Ira

GT ___ 1..J I NG PERFORMANCE: OF'

MIXH:D I-IARDWGC")D rrABL.lETC>P

By :

s r i s u t o p 0

A Project Report is submitted in partial

fulfilment of the requirements for the degree of

Master of science (Wood I ndustries Technology)

Faculty of forestry

Universiti Pertanian Malaysia

November, 1991

i

ACKNOWLEDGEMENT S

I t g ives me great p leasure to express my profound gratitude to Assoc . Pro f . Mohd . Z in Jusoh and Mr . Mohd . Hamami Sahri my research superv i s ors , for thei r guidance in technical research , construct ive criti c i sms and very invaluabl e suggest ions throughout thi s study period .

I wish to convey my deepest appreciati on to Dr . Nana Supriana , Head of the Forest Product Research and Development Centre Bogor for h i s encouragement as wel l as grant ing my official study l eave . Thanks are a l so due to FPRDC-staf f particularly , Dr . Djaban T inambunan , Mr . I shak Sumantri , Mr . Y . I . Mandang , Mr . Barly , Panel Product and Wood Working Div i s i on sta f fs for thei r a s s istance .

s incere thanks are also extended to Assoc . Prof . Dr . Yuso f Hadi , Dean of the Faculty of Forestry for g iv ing me the opportunity to use the fac i l it ies ava i l ab l e and l aboratory sta f f parti cularly Mr . Omar Muhamad for thei r generous assistance in the l aboratory work .

I a l so wish to convey my grat itude to Assoc . Pro f . Dr . Razal i Abdul Kader for the invaluable ass i stance rendered throu9hout the study . I wish to extend my depest apprec1at ion to the ASEAN Timber Technology Centre (ATTCr for the M . S. Scholarship Award .

Last but not least I wish to thank my w i fe Yul i , my son Daru and my two daughters Putr i and I ra for thei r support and encouragements dur ing the study period .

i i

APPROVAL SHEET

TITLE PAGE

ACKNOWLEDGEMENTS

TABLE OF CONTENTS

LIST OF TABLES

LIST OF FIGURES

ABSTRACT

CHAPTER ONE

INTRODUCTION

CHAPTER TWO

T ABLE OF CONT ENT S

LITERATURE REVIEW

2 . 1 Wood species

2 . 1 . 1 2 . 1 . 2 2 . 1 . 3

Yellow meranti Rubberwood Kel empayan

2 . 2 Wood adhes ives

2 . 2 . 1 2 . 2 . 2 2 . 2 . 3 2 . 2 . 4

Adhes ives class i fication Adhes ive composit ion Adhes ives selection Adhes ive used

2 . 2 . 4 . 1 Urea formal dehyde 2 . 2 . 4 . 2 polyvinyl acetate

2 . 3 Preparation of wood before gluing

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Page

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v i

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v i i i

1

4

4

4 5 7

8

9 1 0 1 1 1 2

1 2 1 3

1 4

2 . 4 Glu ing operat ion

2 . 4 . 1 2 . 4 . 2 2 . 4 . 3 2 . 4 . 4 2 . 4 . 5

Preparation of the adhesive Appl ication of the adhes ive The assembly period Pressure and temperature conditioning a fter bonding

2 . 5 Strength performance of gluing

2 . 5 . 1 stren9th propert ies of adhes1ve bonds

2 . 5 . 2 Wood fai lure

CHAPTER THREE

MATERIALS AND METHODS

3 . 1 Adhes ive

3 . 2 Wood species

3 . 3 Wood samples fabrication

3 . 3 . 1 3.3 . 2 3 . 3 . 3

Wood sample preparation Gluin9 and assemb l i ng Press1ng and conditioning

3 . 4 Testing

3 . 4 . 1 Block shear test 3 . 4 . 2 Wet test

3 . 5 Wood fai lure

CHAPTER FOUR

RESULTS AND DISCUSSION

4 . 1 S ingle-species combination

4 . 2 M ixed-spec ies comb inat ion

4 . 3 Reduct ion of shsear strength

4 . 3 . 1 Urea forma ldehyde appl ication 4 . 3 . 2 Polyvinyl acetate appl icat ion

iv

1 6

1 6 1 7 1 8 1 8 19

2 0

2 0

2 1

2 3

2 3

2 4

2 5

2 6 2 6 2 7

2 7

2 8 2 8

2 9

3 0

3 0

3 5

3 7

3 8 4 0

PE,P'J5T /\'</\1\ '\

UNIVERSlTI -'1:lnAN1AN MALAYSIA

4.4 Factors affecting gluing performace 42

CHAPTER FIVE

CONCLUS ION AND RECOMMENDATION 44

REFERENCES 4 7

APPENDICES

v

1-

2 .

3 .

4 .

5.

LIST OF T ABLES

S ingle and mixed combination treatment

Average values of gluel ine shear strength and wood in dry condition .

Average value of gluel ine shear strength and 1ts reduction .

The average shear strength and wood failure of d i f ferent species combination .

Average moisture content �MC) , spec i f ic gravity o f three wood spec1es .

vi

Page

25

3 1

3 3

4 1

4 3

1-

2.

3.

4 .

LIST OF FIGURES

Map o f I ndonesia

Samp l e speciement for shear bl ock test

Shear strength performance of species comb inat i on .

Percentage o f wood .fa i lure & strength reduction .

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Page

25

28

32

3 9

A B S T R A e T

Information of gluing properties suitab i l ity on trop ical wood species is l acking . Thi s study was conducted to provide important information on the pos s ible use of certain species and types of adhes ives .

Gluing performance of three hardwood species i . e . Kel empayan ( Anthocephalus chinens i s ) , Yel low meranti ( Shore� spp . ) and Rubberwood ( Hyveq bras i l iens i§) with

Urea ormaldehyde (UF ) and Polyv1nyl acetate ( PVAc ) was carried out .

The d i fferences between species as wel l as types of adhes ives used showed a very s ign i f i cant e f fect on the glui ng �erformance of the assembled material . Species comb inat1on g lued w ith UF resulted in shear strength exceeded the minimum industrial requ irements o f 5 . 5 MPa and 4 . 1 MPa under dry and wet condit ions respect ively . Ye l l ow meranti s ingle species and Kelempayan-Rubberwood comb inati on under wet condition did not meet the requirement . PVAc glued materials d id not meet the minimum industrial requi rement .

Rubberwood-Rubberwood comb inations glued with UF p roduced boards with h ighest shear strength of 1 0 . 8 MPa and average wood fai lure of 9 3 . 0 per cent . Per­formance of m ixed-species Rubberwood-Kelempayan com­b i nation glued w ith UF produced boards with h i9hest shear strength of 9 . 4 MPa and the average wood fa1lure o f 9 6 . 0 per cent .

Generally , mixed-species combinations resulted in comparable strength properties with s ingl e spec ies combination except that o f Rubberwood glued with UFo Nevertheless , gluing performance of Rubberwood with PVAc improved when combined with Kel empayan or Yel low meranti . Surface qual ity of adherend had a maj or effect in gluing performance especi a l l¥ when PVAc adhes ive was used. Thi s means adherend w1th smoother surface produce worse glu ing per formance .

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CHAPT ER ONE

I N T R O D U C T I O N

Furniture demand i s increas ing continuou s ly

para l lel with populat i on growth ; because new family

normal ly requ ires a new set of furniture . I n the 80's ,

furniture export from ASEAN countries has increased at

very fast rate . Thi s i s due to the pressure of

increas ingly large and soph isticated domestic furniture

market in ASEAN countries ( Anon . , 1 9 9 0 ) .

I n furniture manufacturing , solid wood i s commonly

used for table-top , even though the other materials such

a s plywood , MOF , plastic , even some meta ls and glasses

as table-top are also used . The use of sol id wood

usua l ly based on the natural propert ies and

characteristics such as textures , surface features ,

and their versat i l ity. etc . Robinson (19 6 5 ) stated that

wood has been adapted for furn iture des ign and has

prov ided

flexibi l ity

furniture manufacturers with greater

in production changes than other materi a l s .

ASEAN countr ies in particular Malaysia and I ndones i a

are the major producer of tropical hardwood species .

1

2

One o f disadvantage of sol id wood is that they are rarely

avai l able in b ig s i zes suitable for tabl e-tops . Thi s

h a s posed a cha l lenge for furniture manufactures des i gner

to create a new technology to produce the best of table­

tops w ith reasonable price . Through currently avai l able

technology particu l arly gluing and j o int ing , the

poss ibil ity of making a larger s i z e of t imber suitab l e

f o r the production o f table-tops i s good .

S i ng l e species i s ideal for the product ion of tab l e­

top because o f the homogenous nature . However , the

supply of preferred ' spec ies such as Ramin , Teak ,

Mahogany , and Rosewood , is' becoming scarce and not

suffic ient for future industrial uses . Therefore ,

attempt t o use mixed-hardwood products should be

encouraged to supplement the future shortage .

Gluing i s a process of unit ing two or more

p i eces of s ingle species as wel l as mixed spec ies of

wood us ing adhes ives . Some hardwood species have s imilar

characteristics such as natural colour , textures and

gra in , even some phys ical properties such as shrinkage

and strength . Those s imilarities is important in

uniting and gluing mixed species particularly for

tab l e-top manufacturing. Light coloured wood i s

preferred in furniture market demand in recent years .

Some species such as Ramin (Gonystylus bancanus ) ,

Rubberwood ( Hevea bras i l iens i s ) , and Damar (Agath i s sp . ) ,

3

are popular species for furniture and interior

decoration of wood material s .

other potent ial spec ies such as Kelempayan

( Anthocephalus chinens i s ) , Yel l ow merant i ( Shorea spp . ) ,

are not intensively used

especi a l l y for table-top .

in furn iture

I n formation on gluing properties

product ion

o f tropical

hardwood species and suitab i l ity of adhes ives for table­

top fabricati on i s st i l l lacking . More research work

need to be conducted to provide important basic

informat ion for the proper use of potential wood speci es

and types o f glue for spec ial purpose .

Three species namely Rubberwood , Yel low merant i and

Kelempayan are the potential species for tab l e top

production . However , the performance in relat ion to

gluing has yet to be proven . Therefore it is necessary

to conduct a l aboratory study to assess the suitab i l ity

of wood-adhes ive comb ination . The present study was

conducted w ith the fol lowing obj ectives :

1 . To evaluate the gluel ine shear strength of s ingle

and m ixed species hardwoods tabl e-top us ing Polyv inyl

acetate ( PVAc ) and Urea formaldehyde ( U F ) adhe s ives .

2. To determine the factors a ffecting gluab i l ity

o f mixed hardwoods table-top .

CHAPT ER TWO

LIT ERAT URE REVIEW

Table-top have s i zes which are usua l ly wider

widths of natural timber . Good adhes ives and

glu ing technology could be used to achieve

than

l atest

s i ze

requi rement o f table-top . Al l factors as species o f wood ,

type o f adhes ive , and technical preparation o f substrate ,

have to be con s idered in order to produce a

sat i sfactory product and achieve a certa in qual ity

standard . Final ly the product has to be tested

according to certa in standard .

2.1 Wood species

Three species of wood namely Yel low meranti ( Shorea

spp . ) , Kelempayan ( Anthocephalus chinens i s ) and

Rubberwood ( Hevea bras i l iens i s ) were used for the study :

2.1.1 Yellow meranti

Yel l ow merant i ( Shorea spp . ) i s a popular wood

species in ASEAN countries particularly in Indones ia and

Mal aysia . I n The un ited state ( U . S . A and in The

United Kingdom ( U . K ) these species i s recogni sed as

yel l ow seraya . These spec ies i s commonly used in the

4

5

plywood manufacture . The height of the tree can reach

up to 6 0 m with 150 cm in diameter .

The heartwood is pale-ye l l ow

sometimes with a sl ight green tinge .

to

The

yel low-brown ,

sapwood i s

eas i ly d istingu isable when dry as it i s l ighter colour .

The spec i f i c gravity o f Yel low meranti var ies from 0 . 3 7 -

0�86 and shrinkage 2 . 5 per cent o f radial and 7.5 per

cent of tangential . (Martawij aya et . al , 1 9 81 ) .

Thi s wood can be sawn without d i f ficulty and may be

p laned and moulded to a good f i ni sh . Thi s wood i s

excel lent for j oinery works and a l so suitable for

a l l forms of l ight construction provided it i s not

used in contact with the ground . (Anon . , 19 6 8 ) .

Yel l ow merant i i s sat i s factory for plywood ,

construction and cheap furniture .

2.1.2 Rubberwood

Rubberwood ( Hevea bras i l iens i s) i s the

fl oor

famous

species particularly in I ndones i a and Peninsular

Malaysia . This species has been pl anted in Peninsular

Mal ays ia in the past hundred years ma inly for its latex.

Rubberwood trees are normally replanted a fter atta ining

the age 25 - 3 0 years . Diameter CDBH) of tree can

reach up to 50 cm . ( Anon . , 1 9 88) .

6

The wood i s whithish-yel l ow when freshly cut and

seaSon to pale colour, within a p inkish tinge . The

sapwood i s not d i fferentiated from the

heartwood ( Paul Ng . 19 9 0 ) . Its gra in is general l y stra ight

and its texture moderately coarse . (Tan et . al . , 19 8 1 ) .

Air dry dens ity ranging between 5 6 0 - 6 5 0 kg per cubic

meter averag ing 6 4 0 kg per cub i c meter . Shrinkage 0 . 8

per cent in rad ial and 1 . 2 per cent o f tangent ial from

green to a i r dry at 1 7 per cent moi sture

content . ( Anon . , 19 8 8 ) .

Rubberwood has traditional ly been used as f irewood

and for charcoal manufacture in Peninsular Malays ia .

However , s i nce the early 7 0 ' s , it has been processed

into b lockboard cover and also converted into chips for

pulp and paper making . More recently it has been put to

more sophisticated uses in furniture making and

mou l d ing ( Sal leh and S im , 197 9 in Hoo et . al . , 19 8 2 ) .

It i s being used as a mixture o f rubberwood and

other timber species for the manufacture of knock-down

furniture ( Tan et . al . , 19 81 ) .

Rubberwood i s eas i ly ava i lable in Malays ia and

commonly used in the furniture industry (Mohd . Shukari

et . a l . , 19 8 5 ) . Rubberwood g ive a good f in i sh a fter

plan ing ( S4 S ) and suitable for table-top .

7

2.1.3 Kelempayan

Kel empayan or Jabon i s common name of Anthocephalus

chinen s i s (Lamk . ) A . Rich . ex Walp . I n The united state

( USA ) and in The United K ingdom ( UK ) thi s species i s

recognised as Kadam. The tree usually grown in the

a l l uvial swampy soil at the river bank , or at

the clay podzol ic particularly at the open logged over

areas . The height of the t·ree can reach up to 4 5 m

with d i ameter at breast height of 160 cm .

The wood i s white-yellowish and very d i fficult to

distingui sh between sapwood and heartwood . Wood texture

i s moderately smooth to moderately coarse , and the

usua l ly stra ight . The spec i f ic gravity of 0 . 2 9 -

with an average of 0 . 4 2 . Radial shrinkage o f 3

cent and tangent ial of 6 . 9 per cent .

gra in

0 . 5 6

per

Kelempayan i s commonly used for match

cover , pulp , and l ight construct ion

sticks, box

materials .

It i s a l so very easy

machine and g ive

et . al . 19 89 ) .

to be shaped and

smooth surface

processed by

(Martawijaya

2.2 Wood adhesives

8

Wood adhes ives i s the material commonly used in

wood bondi ng or j ointing to produce wider or longer

p ieces .

Shield ( 19 7 0 ) stated that bas ic function of adhes ive

is to fasten the components of an assembly together and

ma intained the j ointed parts under the serv ices

conditions specif ied by the des ign requ irements .

According to Blomqu ist ( 19 83 ) adhes ive as a substance

capabl e of holding materials together by surface

attachment. Gent et. al. ( 1983} defined the adhesion as the

state in which two surfaces are held together by

interfacial forces which may consist of valence force or

interlocking action , or both . The forces of attract i on

are due to the interaction of molecules , atoms and ions

of the two adj acent surfaces .

Wel l ons ( 19 83 ) stated that wood has two

characteristics that greatly influence its use in bonded

assemb l ies i. e . heterogene ity and variab i l ity . Thus ,

wood adhes ives must be capabl e of bonding adherends that

are both heterogeneous and variable .

9

2.2.1 Adhesives classification

Bas ical ly the adhes ives can be class ified into

various groups based on its character istics and

Kol lmann ( 1975 ) class ified adhes ives into two

system .

groups

based on chemical constituents of the ir ma in composition

i . e . ( 1 ) Natural glues , and ( 2 ) Synthetic glues .

Blomquist ( 19 8 3 ) gave the same class ification of

adhes ives with Kol lmann ( 1 975 ) i . e . natural and synthetic

glues , however he added synthetic elastomers : neoprene ,

n itr i l e , polysulfide . Anon . ( 19 9 0 ) described the

adhes ives based on capabi l ity in its uti l izat ion :

1 . Weather and boil proof type (WBP)

This adhes ives have been proved to make j oints

h ighly res istant to weather , micro organisms , cold and

boi l ing water , steam and dry heat , such as phenol and

resorcinol formaldehyde resins .

2 . Boil resistant type ( BR )

These adhesives have good res istant to weather

and to the boil ing water test, but fa i l under the very

prol onged exposure to weather . This type is also

res istant to micro organisms attack . Example of this

adhes ives is urea - melamine formaldehyde res in .

10

3 . Moisture res istant and moderately weather

resistant type (MR)

These adhes ives providing a high bonding strength

in the dry state , and capable withstanding prolonged

soaking in water at normal temperature . Also res i stant

to micro organisms attack . This adhesive as urea­

formaldehyde resin .

4 . I nterior type ( INT)

These adhes ives should only be used in dry

condition , not res istant to moisture or micro organisms .

Thes e adhes ive may be composed of animal glues, blood

albumin , casein and soya .

2.2.2 Adhesive composition

Wood adhes ives consist of three components namely

base material , solvent and additive materia l s .

Blomqu i st ( 19 8 3 ) specified the component of adhes ive as

fol l ow :

1 . Bas e

be either of natural or This component may

synthetic origin . These material i s usually a

become the "back bone" of the

and which the adhes ive usually

sol id sUbstance

adhes ive film

takes its name , such as pheno l i c resin or epoxy

res in .

11

2 . Solvent

2.2.3

These l iquid materials are required to dissolve

or disperse the base material and additives in

order to provide a l iquid system of all

components for applicat ion to the adherends .

3 . Addit ive material s

Additive could be a

v iscos ity , catalyst

thinner to

to increase

produce low

the rate of

reaction , hardeners , fil lers , extenders ,

preservatives , fortifiers and carr iers .

Adhesives selection

Many factors have to be cons idered based on both

of characteristics , adherends and adhes ive itself .

According to Marra ( 19 8 3 ) two main consideration in

the selection of adhes ives namely : durabil ity and ease of

use . These cons ideration can be specified into four

factors where the adhes ive have to res ist Stress ,

Heat, Mo isture and Organism. Th is factor commonly known

as SHMO - factors . Other important cons iderat ion is

price of the adhes ive .

Bl omquist ( 19 8 3 ) stated that there are three

important factors namely the adherends , mechanical

p ropert ies and cost has to be cons idered during adhes ive

select ion .

12

2.2.4 Adhesive used

Based on the requirement of the study two types of

adhesives have been chosen namely ( 1 ) Urea formaldehyde

(UF ) and polyvinyl acetate ( PVAc ) .

2.2.4.1 Urea formaldehyde (UF)

Urea formaldehyde is a thermosetting resin which

has been used widel y , part icularly in hardwood gluing and

j ointing . stainer and Warren ( 19 8 7 ) stated that

thermosetting adhesives such as UF and PF ( Phenol

formaldehyde ) , have been used to bond wood products for

many decades . Cagl e ( 1973 ) noted that u�ea-formaldehyde

adhesives are widely used in making hardwood plywood and

i n various furniture gluing operation .

Selbo ( 19 6 4 ) stated that urea resin glue bonds are

highly res i stant to cold water , and this supported by

Clark ( 19 6 5 ) noted that urea resin is moderately to

h ighly water res istant and l ow cost .

Sel ler et . al . ( 1 9 9 1 ) said that UF resin are the

cheapest synthetic thermosetting binder for wood , and the

particl e board industry . Low costs and emission

characteristics of UF resins has generated interest in

finding new way of stab ilizing it and make it more

acceptable to the environment .

1 3

Shield ( 1970 ) class ified that U F adhes ives bel ongs

to "moisture res istant and moderately weather res istant

j o ints" ,

years .

and hot

boil ing

can survive ful l exposure to weather for a few

They w i l l withstand cold water for a long period

water for a l imited t ime , but fai l under a

water test . Urea formaldehyde normal ly appl ied

on wood and related mater ials such as thin veneer and

plywood furn iture assembly and j oineries and in the

manufacture of smal l wood part icles at moisture content

l evel between 7 - 15 per cent .

2.2 ••• 2 polyvinyl acetate (PVAc)

Polyvinyl acetate is commonly used in furniture and

j oinery . Clark ( 19 6 5 ) said that polyvinyl acetate has

poor water res i stant properties and suitable only in dry

and interior used type . Shield ( 1 970 ) supported that

PVAc adhes ive is suitable only for furniture and j o inery

i ndustries but not suitable for timber structures .

According to Cagle ( 1973 ) , polyvinyl acetate glue was

formulated and available since the end of World-War II,

and found immed iate appl icat ion in the furn iture

industry , largerly replace animal glues for edge gluing

lumber and for assembly operation . For instances in

fastening chair ring to legs , and in dowel and mortise­

and-tenon j oints .