UNIVERSITI PUTRA MALAYSIA

PROPERTIES OF LAMINATED VENEER LUMBER MANUFACTURED FROM ACACIA MANGIUM THINNINGS AND RUBBERWOOD

(HEVEA BRASILIENSIS)

WONG EE DING

FH 1995 2

PROPERTI E S OF LAMINATED VENEER LUMBER MANUFACTURED FROM Acacia mangium THINNINGS AND

RUBBERWOOD (Hevea brasiliensis)

By

WONG EE DING

The s i s Submitted in Ful f i lment o f the Requi rement s f or the Degree of Mas t e r of S c ience in the

Faculty of Fore s t ry, Unive r s i t i Pertanian Malaysia.

January 1 9 95

Dedicated to

my beloved Dad, Mum, Brothers, Sisters

andC2M

ACKNOWLEDGEMENTS

I would l ike to ext end my utmost grat itude t o t he f ormer Chai rman of my Supervi sory Commi t t ee, As soc. Prof . Dr . Ra zal i Abdul Kade r , f o r h i s unfa i l i ng and invaluabl e guidance throughout the course o f this s tudy. S incere thanks are due to Assoc . Prof . Mohd. Zin Jus oh , A s soc. Prof. Dr . Mohd . Zamin Jumaat, Dr . Mohd . Hamami S ahri , Assoc . Prof . Dr . Ahmad Said Saj ap , Dr . F . S . La i and Dr. Jalaluddin Harun f or their kind support. I am espe cially indebted to Mr . Y . E . Tan and Mr . Omar Khairi

o f FRIM , Kepong , and Mr. Y . S . Chee o f CHG Industries Bhd . , for the i r kind a s s i s t ance in s amp l e f abricat ion and evaluation .

The generous support of Mr . Franc i s Foo o f CHG Indu s t ries Bhd. i s mos t grate ful ly acknowl edged. I n addit i on , I

a l s o wish to thank the f o l l ow ing part i e s f o r kindly providing the neces s ary re search mat erial s and f a c i l i t i e s t o make t h i s s tudy poss ibl e:

Selangor Fore s t Department Fore s t Re s earch Ins t i tute of Mal ays i a ( FRIM ) Dynochem ( M) Sdn . Bhd . Norsechem Re s ins Sdn. Bhd. Engineering Facu l ty and Facul ty o f Fore s t ry , UPM .

Special thanks a l s o go to the Facul ty s t a f f members : Mr . Harmaen , Mr . Omar , Mr . Tal ib , Mr . Zainal , Mr . Yaakob and a l l others who have helped in one way or another.

Last but not least, I would l ike to t hank Mr . C . M. Chew f or h i s pat i ence and encouragement s throughout the durat i on o f my s tudy.

i i i

TABLE OF CONTENTS

Page

ACKNOWLEDGEMENTS LI ST OF TABL E S LI ST OF FIGUR ES

iii vii

x LI ST OF PLATE S . . . . . . . . . . . . . . . . . . . . . . . . . . . . . xii LI ST OF ABBREVIATIONS . . ,., . . ,. , .. . . . . " . " . xiii AB STRA CT AB STRAK

CHAPTER

xiv xvi

I INTRODUCTION 1

Background , . .. .. . .. . . . . . . . . . . . . .. . . . . 1

Ju stification for the Study .......... 4

Ob jective s of the Study . . . . . . . . . . . . . . 6

II LITERATUR E REVI EW 8

Timber Specie s . . . . . . .... . . . . . . . . . . .. . 8

Acacia mangium (Mangium) . . . . . . . . . . . 8

Hevea brasiliensis (Rubberwood) 12

Re sin Adhesives fo r Wood Composites 15

Urea Forma ldehyde (UF) . . . . . . . . . . . . . 16

Me lamine Urea Formaldehyde (MUF) 18

Pheno l Forma ldehyde ( PF) . . . . . . . . . . . 19

Pheno l Re sorcino l Forma ldehyde ( PRF) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20

Sma l l Diameter Log Pee ling Techno logy . . . . . . . . . . . . . . . . . . . . . . . . . . . 22

Laminated Veneer Lumber (LVL) . . . . . . . . 26

Materia l and Proce s sing Variab le s in LVL Manufacture . . . . . . . . . . . . . . . . . . . 28

Wood Species . . . . .. . . . . . . . . . . . . . . ... 28

Adhe sive s/Binder s .................. 31

Veneer Thickne s s and Qua lity . . . . . . . 32

Veneer End Jointing . ............... 35

Veneer Moi sture Content and Temperature . . . . . .. . . . . . . . . . . . . . . . . . 38

Veneer Configuration in LVL . . . .. . . . 3 9

Structura l Finger jointing .. . .... . . .. 40

Applic ations and Uses of LVL . . . . . . . . . 45

Potentia l M arket fo r LVL . . . ,.. . ... ... 46

iv

I I I

IV

MATERIALS AND METHODS Raw Material s Mechanical Propert i e s o f Sma l l

Page

4 8 4 8

Cl ear Sol id Wood . . . . . . . . . . . . . . . . . . . . . 4 9 Green End Veneer Recovery S tudi e s 5 0

B i l l e t Volume . . . . . . . . . . . . . . . . . . . . . . 5 1 Lilypad Lo s s .. . . . . . . . . . . . . . . . . . . . . . 5 1 Bil l e t Volume upon Rounding-up 52 Spur Trim Los s . . . . . . . . . . . . . . . . . . . . . 52 Peeler Core . . . . . . . . . . . . . . . . . . . . . . . . 53

Veneer Recovery . . . . . . . . . . . . . . . . . . . . 53 Round-up Los s . . . . . . . . . . . . . . . . . . . . . . 54

Fabricat i on of LVL . . . . . . . . . . . . . . . . . . . 5 4 Evaluat ion o f LVL . . . . . . . . . . . . . . . . . . . . 5 6

Del amina t i on Te s t . . . . . . . . . . . . . . . . . . 5 7 Bending Shear Tes t . . . . . . . . . . . . . . . . . 5 8 S tat ic Bending Tes t . . . . . . . . . . . . . . . . 5 9

Finger Joint ing o f LVL . . . . . . . . . . . . . . . 6 0 Re inforcement o f Rubberwood LVL u s ing Mangium Veneers

RESULTS AND DI SCUS S ION General . . .. . . . . .. . .. . . . . . . . . . . . . . . . . . Mechani cal Propert ies o f Small Cl ear S o l id Wood o f Mangium and Rubberwood Mangium and Rubberwood : Veneer

62

6 5 6 5

6 7

Recoveri e s and Qua l i ty . . . . . . . . . . . . . . . 71 Propert i e s of S ingle Species LVL from Mangium and Rubberwood . . . . . . . . . . 8 0

Den s i ty and Moi s tu re Content . . . . . . . 80

Thickne s s Swelling and Wat er Ab s orp t i on . . . . . . . . . . . . . . . . . . . . . . . . . 82 Delaminat i on . . . . . . . . . . . . . . . . . . . . . . . 84

Shear S t rength . . . . . . . . . . . . . . . . . . . . . 8 6 S t a t i c Bending . . . . . . ... . . . . . . . . . . . . 9 5

Bending S trength o f Finger-jointed Mangium and Rubberwood LVL . . . . . . . . . . . 1 0 6 Reinf orcement o f Rubberwood LVL us ing Mangium Veneer 113

v

Page

Den sity and Moi sture Content . . . . . . . 1 1 6

Thickne s s Swelling and Water Ab sorption . . . . . . . . . . . . . . . . . . . . . . . . . 118

Shear Strength (Dry and Wet) . . . . . . . . . 1 2 1

Static Bending . . . . . . . . . . . . . . . . . . . . . 1 25

V SUMMARY 1 3 2

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

Recommendation s for Future Studie s 1 3 4

BIBLIOGRAP HY 1 3 7

A P P ENDIX A Re sin Specification s and Glue Mix

Formulation s . . . . . . . . . . . . . . . . . . . . . . . . . 1 5 2

B Additional Tables . . . . . . . . . . . . . . . . . . . . . . 1 5 4

VITA 17 0

vi

Table

1

2

LIST OF TABLES

St rength P rope rties of Acacia mangium

(M angium) and Hevea brasiliensis

(Rubberwood) . . . . . . . . . . . . . . . . . . . . . . . . .

P rope rties and Uses of St ru ctu ral Lumbe r . ..... .... . .. . . . . . .... . . . ... . . .

3 Joint F acto r fo r V arious S c arf

4

Slopes in Venee r Jointing

P rope rties of Small Clear Solid Wood of M angium and Rubbe rwood

5 Density and Moisture Content of Solid

Page

1 0

27

3 7

6 9

Wood and LVL of Mangium and Rubberwood 8 2

6 Thickness Swelling and Wate r Abso rption of M angium and Rubbe rwood LVL . . . . . . . . 8 3

7 Density and Moistu re Content of Venee r and Reinfo rced Rubbe rwood LVL . . . . . . . . 1 17

8 Thickness Swelling and Wate r Abso rption of Reinfo rced Rubberwood LV L . . . . . . . . . 1 1 9

9 Ten-ye ar old Mangium G reen Venee r Re cove ries .. . .. . . . . . . . . . . . . . . . . . . .. . . 154

1 0 Old-g rowth Rubberwood G reen Venee r Recove ries

1 1 Shear Strength o f Solid Wood and LVL

155

of M angium and Rubbe rwood . . . . . . . . . . . . 156

12 Modulus of El asti city (MOE) of Solid Wood and LV L of Mangium and Rubbe rwood. 1 5 7

1 3 Modulus of Rupture (MOR) of Solid Wood

and LVL of M angium and Rubberwood 158

vii

Table

1 4 Modulu s of Elas t i c i t y ( MOE ) of Finger - jointed and Unjointed Mangium

Page

and Rubberwood LVL . . . . . . . . . . . . . . . . . . . 159

1 5 Modulus o f Rupture ( MOR ) o f Finger­jointed and Unjointed Mangium and Rubberwood LVL . . . . . . . . . . . . . . . . . . . . . . . 1 6 1

1 6 Dry and Wet Shear S t rengths of Reinforced Rubbe rwood LVL . . . . . . . . . . . . 163

17 Modulu s of Elas t i c i ty ( MOE ) of Reinforced Rubberwood LVL . . . . . . . . . . . . 164

18 Modulus of Rupture (MOR ) of Reinforced

Rubberwood LVL . . . . . . . . . . . . . . . . . . . . . . . 1 6 4

1 9 ANOVA Table f or E f f e c t s of Vene er Species , Resin Type and Venee r Configurat ion on Flatwi s e , Edgewi s e and Mean Shear S t rengths of LVL . . . . . . 165

20 ANOVA Table for E f fe c t s of Veneer Species , Re s i n Type and Venee r Conf igurat ion on Flatwise , Edgewise and Mean Modulus of Elas t i c i ty ( MOE ) of LVL . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1 6 6

21 ANOVA Table for Effects of Veneer Species, Re s i n Type and Veneer Configuration on Fiatwis e , Edgewis e and Mean Modulus of Rupture ( MOR ) of LVL . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1 6 7

22 ANOVA Table for E f fe c t s of Venee r Spec i e s , Re s in Type and Venee r Configurat ion on Flatwi s e , Edgew i s e and Mean Modulus o f Elas t i c i ty ( MOE ) of Finger-jointed LVL . . . . . . . . . . . . . . . . 1 6 8

viii

Table

23 ANOVA Table fo r Effect s of Venee r Specie s, Re sin Type and Veneer Configu ration on Flatwi se, Edgewise and Mean Modulu s of Ruptu re (MOR)

Page

of Finge r-jointed LVL . . . . . . . . . . . . . . . . 168

24 Standa rd St rength G roup Cla s sification

2 5

2 6

Table . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16 9

LVL Shea r Strength Standa rd 16 9

LVL Bending St rength Standa rd 16 9

ix

Figure

1

2

3

4

5

6

7

8

9

LIST OF FIGURES

Recovery Component s of Pee ler Log

Symmetrical ( a ) and Non - symme trical ( b ) Veneer Configurat ions i n LVL Const ruction . . . . . . . . . . . . . . . . . . . . . . . . .

Finger Profile in LVL Joint ing

Orientat ion of Finger Joint in Fl atwise (a ) and Edgewise ( b ) S tatic Bending of Jointed LVL . . . . . . . . . . . . . . .

Reinforcement of Rubberwood LVL us ing 3 ( a ) and 5 ( b ) Mangium Pl ies in the Faces . . . . . . . . . . . . . . . . . . . . . . . . .

Green Veneer Recovery Component s of Mangium and Rubberwood . . . . . . . . . . . . . . .

Total Green Veneer Recoveries for Mangium ( a ) and Rubberwood ( b ) based on Diameter Class . . . . . . . . . . . . . . . . .

Shear S trength of Solid Wood and LVL of Mangium and Rubberwood . . . . . . . . . . . .

Flatwise and Edgewise Shear Stre ngths of Mangium and Rubberwood LVL . . . . . . . .

1 0 MOE o f Solid Wood and LVL of Mangium and Rubberwood

1 1 MOR of Solid Wood and LVL of

Page

5 0

5 5

6 0

62

6 3

76

7 8

8 8

9 4

9 7

Mangium and Rubberwood . . . . . . . . . . . . . . . 1 0 0

1 2 Flatwise and Edgewi se MOE ( a ) and MOR ( b ) of Mangium and Rubberwood LVL . 1 0 1

1 3 Mean MOE of Unjointed and Finger-j ointed Mangium and Rubberwood LVL 1 0 7

x

Figure

14 Mean MOR of Unj ointed and Finger-

Page

j ointed Mangium and Rubberwood LVL 1 0 9

15 Flatwis e and Edgewise MOE of Finger-j ointed Mangium and Rubberwood LVL 1 1 2

1 6 Dry and Wet Shear S trengths of Reinforced Rubberwood LVL . . . . . . . . . . . . 1 2 2

1 7 Flatwi se and Edgewise MOE of Reinforced Rubberwood LVL . . . . . . . . . . . . 1 2 6

1 8 MOE o f Reinforced Rubberwood LVL Compared to Sol id Wood and S ingle Species LVL . . . . . . . . . . . . . . . . . . . 1 2 8

1 9 MOR o f Reinforced Rubberwood LVL Comp.ared to Sol id Wood and S ingl e Species LVL . . . . . . . . . . . . . . . . . . . 1 2 9

xi

LIST OF PLATES

Plate

1 Peeler Blocks of 1 0 - year old Mangium Thinnings . . . . . . . . . . . . . . . . . . . .

2 Old- growth Rubberwood Peeler Bl ocks

3 Mangium Veneer (Green)

4 Rubberwood Veneer (Green)

5 Fl atwi se Shear Failure in Mangium

Page

7 3

7 3

7 4

7 4

and Rubberwood LVL . . . . . . . '" . . . .. . . . . 9 1

6 Tens ile Failure in Flatwise S tatic Bending of Mangi um LVL . . . . . . . . . . . . . . 9 8

7 Tens ile Fai lure in Fl atwi s e Static Bending of Rubberwood LVL . . . . . . . . . . 98

8 Shear Failure in S tat ic Bending of PF Bonded Rubberwood LVL . . . . . . . . . . . . . . . . 9 9

9 Typi cal Joint Fai lure in Edgewise S tatic Bending of Finger- j ointed LVL of Mangium and Rubberwood . . . . . . . . 1 1 0

1 0 Tens ile Failure i n Fl atwi s e Static Bending o f Finger- j ointed LVL . . . . . . . . 1 1 0

1 1 End-j ointed ( 1 : 3 S carf Joint ) 8 - f t Long Dry Rubberwood Veneers . . . . . . . . . . . . . . . 1 1 9

1 2 Uneven Scarf Joint Surface i n Wavy Rubberwood Veneer

13 Delamination Spec imens of MUF Bonded Reinforced LVL after Boil ing

1 2 0

Water S oak Tes t . . . . . . . . . . . . . . . . . . . . . . 1 2 0

xi i

ATTC CV FRIM f t hr LVL MC MOE MOR MT IB MUF NaPCP OD PF PRF SD TS UF USDA WA

LIST OF ABBREVIATIONS

ASEAN Timber Technol ogy Centre coe f f icient o f vari at ion Forest Research Ins t i tute o f Malaysia f oot hour l aminated veneer lumber mois ture content modulus of elast icity modulus o f rupture The Mal ays ian Timber I ndu s t ry Board me l amine urea f ormaldehyde s odium pentachl orophenat e oven dry phenol formaldehyde phenol res orcinol f ormaldehyde s t andard deviation thickne s s swe l l ing urea f ormaldehyde U . S . Department of Agricul ture water absorp t i on

xi i i

Abstract of thesis submitted to the Senate of

Universiti Pertanian Malaysia in fulfilment of the

requirements for the degree of Master of Science.

PROPERTIES OF LAMINATED VENEER LUMBER MANUFACTURED

FROM Acacia mangium THINNINGS AND

RUBBERWOOD (Hevea brasiliensis) .

By

WONG EE DING

DECEMBER 1 9 9 4

Chairman Associate Professor Mohd. Zin Jusoh

Faculty Faculty of Forestry

This study attempts to assess the properties of

structural laminated veneer lumber (LVL) made from low

grade raw materials and produced on commercial plywood

and LVL lines. Ten-year old Acacia mangium (Mangium)

thinnings and old-growth Hevea brasiliensis (Rubberwood)

were peeled to 3.6 mm thick veneers and processed into

IS-ply LVL. Two different veneer configurations were

used in the LVL fabrication, with melamine urea

formaldehyde (MUF) , phenol formaldehyde (PF) and urea

formaldehyde (UF) as binders. The LVL were subsequently

finger-jointed and the bending strength evaluated. The

properties of LVL with different proportions of Mangium

and Rubberwood were also evaluated. Total green veneer

recoveries of about 70% were recorded for both Mangium

and Rubberwood, using a 4-ft Meinan Aristo-lathe. In

xiv

general, Rubberwood demonstrated good compatibility with

UF resin, whilst MUF performed better than PF. Veneer

configuration did not have significant (P�0.05) effect on

the mechanical properties of the LVL. Evaluation of the

LVL based on the Japanese Agricultural Standard for

Structural LVL (1993) showed that besides having

negligible delamination and fulfilling the shear

requirements for various LVL grades, MUF and PF bonded

Rubberwood LVL met the 80E Special Grade, whilst

Rubberwood LVL with UF, and all of the Mangium LVL met

the minimum modulus of elasticity (MOE) requirement for

120E Special Grade Structural LVL. The modulus of

rupture (MOR) were exceedingly high in all cases. The

laminating process resulted in about 30% reduction in

MOR, but a pronounced improvement in MOE by up to 86%,

compared to small clear solid wood. Finger-jointing

resulted in 79 to 88% joint efficiency in terms of MOR,

with no reduction in MOE. Combination of 10 Mangium

plies with five Rubberwood plies (core) passed the 100E

Special Grade, whereas pure Rubberwood and combination of

six Mangium plies with nine Rubberwood plies (core) only

met the requirements for aOE Special Grade. Both

physical and mechanical properties of the LVL evaluated

showed high uniformity as indicated by their low

coefficient of variation « 10%). The results obtained

are positive indications for both Mangium thinnings and

Rubberwood to be upgraded for structural uses through

processing into LVL.

xv

Ab st rak te si s dikemukakan kepada Senat Unive rsiti

Pe rtanian Malay sia untuk memenuhi keperluan Ijazah Ma ster Sain s .

SIFAT PAPAN VENIR BERLAMINA (LVL) YANG DIPERBUAT

DARIPADA KAYU PENJARANGAN Acacia mangium DAN

KAYU GETAH (Hevea brasiliensis) .

Oleh

WONG EE DING

DISEMBER 1994

Penge ru si P rofe sor Madya Mohd. Zin Ju soh

Faku lti Fakulti Pe rhutanan

Kajian ini bertujuan menilai mutu papan veni r berlamina

(LVL) yang dipe rbuat da ripada ba han bermutu rendah ,

dengan menggunakan kemudahan-kemudahan sedia ada di

ki lang papan lapi s dan kilang LVL. Bahan penj a rangan

da ri hutan ladang Aka sia (Acacia mangium) (umu r 10 tahun)

dan Kayu Getah (Hevea brasiliensis) dikupas menjadi veni r

(3.6 mm teba l) , dan dip ro se s menjadi LVL (15 lapi san)

dengan men ggunakan melamin urea formaldehid (MUF), fenol

formaldehid (PF) dan u rea fo rma ldehid (UF) sebagai

pe rekat . Kedua-duanya , iaitu Akasia dan Kayu Getah

mencatat pUlangan venir setinggi 70% dengan menggunakan

"Meinan A ri sto- lathe" sepanjang 4 -kaki . Walaupun

Aka sia didapati ku rang se ra si dengan U F , tetapi Kayu

Getah mengha silkan ikatan yang kuat dengan UFo Pada

xvi

keseluruhannya , ikatan MUF adalah lebih baik dari PF .

Kekuatan LVL didapati t idak dipengaruhi oleh Corak

susunan veni r . Kesan tanggam j ej ari ( f inger j oint )

yang dikaj i mel alui uj ian l entur mencatatkan 7 9

hingga 8 8 % keberkesanan sarnbungan bagi modulus patah

(modulus of rupture - MOR) , tanpa mengurangkan modulus

kekenyal an (modulus of el asticity MOE ) . Penilaian

berasaskan Japanese Agricul tural S tandard ( JAS ) LVL untuk

Kegunaan Struktur ( 1 9 9 3 ) menunj ukkan bahawa , selain

daripada mencatat kadar delaminas i yang rendah , LVL yang

dihasilkan mencapai gred- gred kekuatan ricih yang

berl ainan . LVL Kayu Getah yang di rekat dengan MUF dan PF

mencapai Gred Khas 8 0 E , manakala LVL Kayu Get ah dengan

UF , dan kesemua LVL Akas ia mencapai Gred Khas 1 2 0E . MOR

kayu pej al telah menurun sebanyak 3 0 % dengan penghas i l an

LVL , tetapi nilai MOE telah meningkat s ebanyak 8 6 % .

Kornbinas i spe s i s venir dengan menggunakan 1 0 l apisan

Akasia di perrnukaan dan l ima l apisan Kayu Getah di

bahagian tengah mencapai Gred Khas 1 0 0 E , manakal a LVL

Kayu Getah dan enam l apisan Akasia campur dengan sernbi l an

l ap i s an Kayu Getah hanya mencapai Gred Kha s 80E. Dal am

semua kes , keseragaman kekuatan LVL adal ah amat t inggi ,

dengan varias i koef i s ien yang kurang daripada 1 0 % .

Keputusan kaj ian menunj ukkan Akasia dan Kayu Getah

mempunyai potensi yang baik untuk diproses menj adi LVL

bagi kegunaan struktur .

xvi i

CHAPTER I

INTRODUCTION

Background

Over the decades , forestry and forest - based industry have

been playing a s igni f icant role in the Malays ian e conomy .

The export revenue f rom timber and t imber products has

general ly been on the rise . In 1 9 9 2 , i t contributed

approximately RM 1 0 . 5 bill ion represent ing about 3 1 . 3 % of

the total nat ional commodity export earnings , ranking

second only to petroleum and petrol eum products ( MTIB ,

1 9 9 4 ) . Besides , this sector al so provided empl oyment to

about 2 3 5 , 0 0 0 people or 3% of the country ' s l abour force

( I smail , 1 9 9 3 ) .

In recent years , the Malays ian wood- based industry

experienced phenomenal growth , standing with a total of

1 , 1 5 0 sawmi l l s , 1 2 0 veneer/plywood mil l s , 97 wood

moulding and 3 0 0 furni ture plants ( export oriented wooden

furniture f actories only) in 1 9 9 2 ( Ministry of Primary

Indus tries , 1 9 9 3 ) . In

of industrial isat ion ,

l ine with the Government ' s pol i cy

i t is anticipated that the

1

2

industry will cont inue to grow , e special ly towards

downstream proces s ing of high value product s . By far , it

cannot be denied that the avai l abil i ty of cheap and

good qual i ty raw material s , i . e . , l ogs and cellulosic

material s of suitable forms , i s one of the key factors

respons ible for the development of the Malaysian fore s t ­

based industry . The increas ing demand of raw material

input for the industries , coupled with agri - convers ion

and cl earing of forested- areas for development have

however , resulted in accelerated rate of harvest ing .

Thi s in turn threatens the sustainabil i ty of t imber yield

from the natural forests . The total forested area in

Peninsular Malaysia has dropped f rom 6 . 45 mi l l i on ha ( 4 9 %

o f the total l and area ) i n 1 9 7 9 t o 5 . 9 6 mi l l ion ha in

1 9 9 2 , with only 2 . 8 3 - mil l ion ha of product ive fores t .

Based on the se f igures , i t can be deduced that about

3 7 . 6 9 thousand ha of forests were lost each year due to

the above ment ioned act ivities during the said period

( I smail , 1 9 9 3 ) .

A comparison of the annual l og supply and demand pattern

revealed that Malaysia on the whol e , wil l face log

def i c i t s after the year 2 0 0 0 . One of the alternat ive s t o

guarantee sustainable supply of t imber raw material s i s

through cul t ivat ion of plantat ion t imber c rops . Whi l s t

many temperate countries are al ready way ahead into

3

forest plantation , Mal aysia only started sma l l scale teak

pl ant ation in 1 95 7 . Between 1 960s and 1 970s , about

5 , 500 ha o f tropical conifers (pines and Araucaria) were

established. In 1 982, Compensat ory Forest Plantation

Programme was initiated with the object of supplying

general utility timber to the wood-based industries.

Among the many f ast growing tree species promo ted in

Mal aysia , Acacia mangium (Mangium) is one of the

most dominant species at the moment. Mangium covers

some 80% o f the total plantation area (51, 745 ha)

es tablished in Peninsular Malaysia (Hashim et. al. ,

1 9 9 0). Compared to the forest plantation trees which are

yet to mature , Hevea brasiliensis (Rubberwood) is already

widely in use commercial l y , especial ly in furniture

manufac turing . Utilisation of Rubberwood has been

reported t o increase from about 1 0 0,0 0 0 m3 in 1 980 t o

1 . 84 mil lion m3 i n 1 9 9 2 (Ismail, 1 9 9 3 ) .

Despite having the advant age of being fast growing , the

logs of the above-mentioned species, however , have

smaller diameters with lower density and higher growth

defects ( knotty , high growth stress and high percentage

of juvenile wood) , compared to that from the natural

forests. Nonetheless , most of the l ocal industries are

al ready adapting wel l t o the technol ogy o f smal l l og

processing, where appropriate skil ls and machinery have

been brought in to optimise recoveries. To this end , the

4

main focus of process ing has been on the manuf acture of

wood-based compos ite product s , as it is the only

al ternat ive to recover l arge dimens ion timber f rom smal l ­

s i z ed l ogs ; be i t i n the form o f glue l aminat ion

(veneer and solid wood) , or reconst i tution of

part icles or f ibres . These manufacturing proces ses make

it pos s ible to produce compos ites of tai lored des irable

properties for various end-uses , whi ch in this c ase is

achieved either through appropriat e manipul at i on of raw

material inputs and/or proce s s variables .

Jus t i f i cat ion for the S tudy

In Mal ays i a, in 1 9 9 1 alone , the construction sector

accounted for about 6 0 % of the total s awn t imber

consumption , i . e . , some 1 , 6 1 0 , 6 0 0 m3 out of a total of

2 , 6 7 9 , 8 0 0 m3 avail able for consumption ( Lockman and Poh ,

1 9 9 2 ) . In l ight of the expected growth of the

hous ing/ cons truction s ector in the country , at l eas t for

the next few years , the demand for structural wood

products is expected to increase further . However , with

the diminishing supply of l arge - s i zed logs from natural

fores t s , there would s oon be l imited solid - s awn timber of

suf ficiently l arge dimens ion for structural uses ; or

solid t imber might then become an unaf fordable

construct ion opt ion . There i s therefore a need to

5

devel op new engineered product s from our new future wood

resource fast growing smal l diameter l ogs to be

used as substitutes for dimensional sol id - sawn timber .

In the Mangium plantat ion , thinning operat ions are being

carried out at the ages of two to four and eight to

nine . The resul tant thinning material s are of sma l l s i ze

and l ow dens i ty , and could either be processed into

charcoal or composite products such as part icleboard or

f ibreboard . Nevertheles s , it has been shown that

8 - 9 years old thinnings wi th minimum diameters of

about 18 cm are peelable using the exi s t ing small l og

peel ing technology ( Chai , 1 9 8 9 ; Sas aki et al . , 1 9 9 0 ;

Wang e t al . , 1 9 9 0 ; Sal im , 1 9 9 2 ; Louko , 1 9 9 3 ) . The

veneers were reported to be suitable only f or plywood

core material s , mainly due to the presence of knot hole s

and s trong colour contrast between sapwood and heartwood .

Ins tead of us ing these material s as l ow - cost plywood

core - s tock as sugges ted ( Gregor , 1 9 9 3 ; Louko , 1 9 9 3 ) , it

would however , be far more economical to process them

into laminated veneer l umber ( LVL ) for structural uses ,

where appearance is not of critical importance , so l ong

as the end product has acceptabl e dimensional and

mechanical propert ies .

Despite being . wel l es tabli shed for the manufacture of

numerous product s , u t i l i sat ion of Rubberwood has in

f ac t , yet to be ful ly opt imi sed . In view o f the

6

compet it ive demand f or Rubberwood , i t i s deemed

important to further invest igate and broaden the

other pos s ible end -produc t s , in upgrading its

ut i l i sation s tatus and fetching the highes t p os s ible

value . Bes ides produc ing s ingl e - species LVL ,

c ombinat i on of Mangium and Rubberwood will al s o

resul t i n generat i on of a new product with spec i f i c

properties f or certain appl icat i ons .

This study was c onducted t o inves t igate the e f fects of

sel ected proce s s ing variabl es on the propert ies of

interior and exteri or grade LVL f r om the l ow - grade 1 0 -

year old Mangium thinnings and old - growth ( 2 5 - 3 0 years

old) Rubberwood.

Object ives o f the S tudy

Thi s s tudy aims to invest igate the e f fects of s ome

selected proce s s ing variabl es on the propert ies of LVL

made f rom 1 0 - year old Mangium thinnings and 2 5 - 3 0 years

old Rubberwood :

a . mechani cal propert ies of small clear s ol id wood

specimens of Mangium and Rubberwood i

b . green end veneer recoveries f or small diameter l ogs

i . e . , Mangium thinnings and Rubberwood i

c .

d .

7

properties of IS -ply mono - species LVL made from

3 . 6 mm thick Mangium and Rubberwood veneers bonded

with melamine urea formaldehyde (MUF ) , phenol

formaldehyde ( PF ) and urea f ormaldehyde ( UF ) res in

adhes ives j

the effects of veneer conf igurat ion ( symmetrical /non-

symmetri cal ) on phys ical and mechani cal propert ies of

Mangium and Rubberwood LVL ;

e . the bending s trengths of f inger - j ointed 2 4 3 8 mm

(8 - ft ) long Mangium and Rubberwood LVL j

f . the ef fects of Rubberwood LVL reinforcement us ing 3

and S plies of Mangium veneers in the tens ion ­

compres s ion z one s ; and

g . to compare the propert ies of LVL manufactured with the

requirement s s t ipulated in Japanese Agri cul tural

S tandard ( JAS ) for S tructural LVL ( 1 9 9 3 ) .