mechanical properties of styrene butadiene rubber with oil palm trunk

MECHANICAL PROPERTIES OF STYRENE BUTADIENE RUBBER WITH OIL

PALM TRUNK FIBER AS FILLER

MOHD HAZIZUL BIN HAMZAH

UNIVERSITI MALAYSIA PAHANG

UUNNIIVVEERRSSIITTII MMAALLAAYYSSIIAA PPAAHHAANNGG

BBOORRAANNGG PPEENNGGEESSAAHHAANN SSTTAATTUUSS TTEESSIISS

JUDUL : MECHANICAL PROPERTIES OF STYRENE BUTADIENE RUBBER

WITH OIL PALM TRUNK FIBER AS FILLER

SESI PENGAJIAN : 2010/2011

Saya MOHD HAZIZUL BIN HAMZAH

(HURUF BESAR) mengaku membenarkan tesis (PSM/Sarjana/Doktor Falsafah)* ini disimpan di Perpustakaan Universiti

Malaysia Pahang dengan syarat-syarat kegunaan seperti berikut :

1. Tesis adalah hakmilik Universiti Malaysia Pahang

2. Perpustakaan Universiti Malaysia Pahang dibenarkan membuat salinan untuk tujuan pengajian

sahaja.

3. Perpustakaan dibenarkan membuat salinan tesis ini sebagai bahan pertukaran antara institusi

pengajian tinggi.

4. **Sila tandakan ( √ )

SULIT (Mengandungi maklumat yang berdarjah keselamatan atau

kepentingan Malaysia seperti yang termaktub di dalam

AKTA RAHSIA RASMI 1972)

TERHAD (Mengandungi maklumat TERHAD yang telah ditentukan

oleh organisasi/badan di mana penyelidikan dijalankan)

√ TIDAK TERHAD

Disahkan oleh

(TANDATANGAN PENULIS) (TANDATANGAN PENYELIA)

Alamat Tetap No.12, Jalan PJS 2C/9 Mr. Mohd Bijarimi Mat Piah

Taman Medan, 46000 Nama Penyelia

Petaling Jaya, Selangor

Tarikh : 26 JANUAR1 2007 Tarikh

CATATAN : * Potong yang tidak berkenaan.

** Jika tesis ini SULIT atau TERHAD, sila lampirkan surat daripada pihak berkuasa/organisasiberkenaan dengan menyatakan sekali sebab dan tempoh tesis ini perlu dikelaskan

sebagai SULIT atau TERHAD.

Tesis dimaksudkan sebagai tesis bagi Ijazah Doktor Falsafah dan Sarjana secara

penyelidikan, atau disertasi bagi pengajian secara kerja kursus dan penyelidikan, atau

Lapuran Projek Sarjana Muda (PSM).

MECHANICAL PROPERTIES OF STYRENE BUTADIENE RUBBER WITH

OIL PALM TRUNK FIBER AS FILLER

MOHD HAZIZUL BIN HAMZAH

A thesis submitted in fulfillment of the requirements for the award of the Degree of

Bachelor of Chemical Engineering

Faculty of Chemical & Natural Resources Engineering

Universiti Malaysia Pahang

DECEMBER 2010

ii

“I hereby declare that I have read this thesis and in my opinion this thesis has

fulfilled the qualities and requirements for the award of Degree of Bachelor of

Chemical Engineering (Chemical/Biotechnology/Gas Technology)”

Signature : …………………………

Name of Supervisor I : Mohd Bijarimi Bin Mat Piah

Date : …………………………

iii

I declare that this thesis entitled “Mechanical Properties of Styrene Butadiene

Rubber with Oil Palm Trunk Fiber as Filler” is the result of my own research except

as cited in references. The thesis has not been accepted for any degree and is not

concurrently submitted in candidature of any other degree.”

Signature : ………………………………

Name : Mohd Hazizul Bin Hamzah

Date : 3 December 2010

iv

For my beloved father and mother for always stood by my back in joy and sorrow.

Tomorrow is there for us even if we fall down. Success will always stay by our side if we

stand up and face forward. Thanks father, mother for your unlimited support and

inspiration. I love both of you. Always!

v

ACKNOWLEDGEMENT

With the name of HIM, our Creator, The Almighty, with HIS help and guidance, I

was able to complete this Undergraduate Research Project.

I would like to take this opportunity to extend our gratitude to all parties that

involved in this research especially my supervisor, En. Mohd Bijarimi Bin Mat Piah.

With his help, I acquired more knowledge that cannot be obtained during class.

I hope that this thesis report will be a help to all reader in the future for more

knowledge and improvement later. This research – “Mechanical Properties of Styrene

Butadiene Rubber with Oil Palm Trunk Fiber as Filler” will hopefully give some ideas

for later reading or study.

Last but not least, to all my friends who have landed me help regarding

information and knowledge, there is no words can describe how much I owe and thank

you.

vi

ABSTRACT

Synthetic rubber on the other hand is a rubber which is synthesized chemically.

Styrene-butadiene rubber is one of them. The synthetic rubber gives different properties

from natural rubber in every aspect. The objectives of this research are to investigate the

mechanical properties changes in styrene butadiene rubber (SBR) filled with oil palm

trunks as fillers and to check the differences in properties between the amounts of fillers

used. The purpose of this research is to investigate the properties of styrene butadiene

rubber blending with oil palm trunk fiber as filler. The research is based on experimental

lab research. The contribution of oil palm trunk as a filler in rubber compound will

decrease the burning activities and reducing environmental issues. Many researches have

been done in rubber/natural filler blending in order to improve the properties of rubber

with economically. The methods in this research are divided into three sections; mixing,

molding, and testing. Mixing required two roll mills as a device blending rubber with

filler, accelerator and vulcanizing agent. Molding required hot and cold press molding to

form a sheet of product before testing. Testing required a universal testing machine to test

the tensile properties of the rubber blend. Two chemical used in this swelling test;

kerosene and diesel. The samples were put into two different bottles with kerosene inside

one bottle and diesel inside another bottle. The time taken to complete the test was 24

hours – exactly one day. The result from testing showed that increasing amount of fillers

will actually decrease the tensile strength, increase the tensile modulus and increase

swelling behavior of the rubber blend. As conclusion, most of mechanical properties

decrease with increasing of filler content. As recommendation, increasing the filler

content might give the better result, and giving more information about capability of

styrene butadiene rubber to consume more filler.

vii

ABSTRAK

Getah sintetik di sisi lain adalah getah yang merupakan hasil campuran bahan

kimia. Getah stirena butadiena adalah salah satunya. Getah sintetik memberikan sifat

yang berbeza dari getah asli dalam setiap aspek. Tujuan kajian ini adalah untuk

mengetahui perubahan sifat mekanik dalam getah stirena butadiena (SBR) yang diisi

dengan batang kelapa sawit sebagai suapan dan untuk menyemak perbezaan sifat antara

jumlah suapan digunakan. Tujuan dari penelitian ini adalah untuk mengetahui sifat-sifat

campuran getah stirena butadiena dengan serat batang kelapa sawit sebagai suapan.

Penelitian ini berdasarkan pada penelitian ujikaji makmal. Sumbangan batang kelapa

sawit sebagai isian dalam campuran getah akan menurunkan kegiatan pembakaran dan

mengurangkan masalah alam sekitar. Banyak kajian telah dilakukan dalam

getah/pencampuran isian asli meningkatkan sifat getah dengan ekonomi. Kaedah dalam

kajian ini dibahagikan kepada tiga bahagian; pencampuran, pencetakan, dan ujian.

Mencampur memerlukan “two roll mill” sebagai campuran getah peranti dengan isian,

pencepat dan agen vulcanizing. Pencetakan memerlukan “hot and cold molding press”

untuk membentuk sehelai produk sebelum ujian. Ujian memerlukan mesin uji universal

untuk menguji sifat tarik dari getah campuran. Dua kimia yang digunakan dalam ujian

pembengkakan ialah minyak tanah dan diesel. Bahan uji dimasukkan ke dalam dua botol

yang berbeza dengan minyak tanah dalam satu botol dan diesel dalam botol lain. Waktu

yang diperlukan untuk menyelesaikan ujian adalah 24 jam - persis satu hari. Hasil dari

ujian menunjukkan bahawa peningkatan jumlah suapan benar-benar akan menurunkan

kekuatan tarik, meningkatkan modulus tarik dan meningkatkan perilaku pembengkakan

getah campuran. Sebagai kesimpulan, sebahagian besar sifat mekanik menurun dengan

peningkatan kadar isian. Sebagai cadangan, meningkatkan kadar isian dapat memberikan

hasil yang lebih baik, dan memberikan maklumat lebih lanjut tentang kemampuan getah

stirena butadiena untuk mengambil lebih banyak isian.

viii

TABLE OF CONTENTS

CHAPTER TITLE PAGE

DECLARATION ii

DEDICATION iv

ACKNOWLEDGEMENT v

ABSTRACT vi

ABSTRAK vii

TABLE OF CONTENTS viii

LIST OF TABLES xi

LIST OF FIGURES xii

LIST OF APPENDICES xiv

LIST OF ABBREVIATIONS xv

1 INTRODUCTION

1.1 Background of Study 1

1.2 Problem Statements 2

1.3 Objectives of the Research 3

1.4 Scope of Study 3

1.5 Rationale and Significance 4

2 LITERATURE REVIEW

2.1 Styrene Butadiene Rubber 5

ix

2.2 Natural Filler 6

2.3 Oil Palm Trunk Fiber 6

2.4 Crosslink 7

2.5 Vulcanization 7

2.6 Mechanical Properties 8

2.6.1 Tensile Strength 8

2.6.2 Tensile Modulus 10

2.6.3 Swelling 12

2.6.4 Elongation 13

2.7 Recycled Elastomer 14

2.8 Carbon Black Filler 16

2.9 Organoclay 19

3 METHODOLOGY

3.1 Chemical and Apparatus 20

3.2 Rubber Formulation 21

3.3 Sieving 22

3.4 Blending 23

3.5 Molding 24

3.6 Tensile Test 25

3.7 Swelling Test 26

3.8 Precaution Steps 27

4 RESULTS AND DISCUSSIONS

4.1 Result 28

4.1.1 Tensile Test 28

4.1.2 Swelling Test 29

4.2 Discussion 30

4.2.1 Time to Break 30

4.2.2 Tensile Strength 31

4.2.3 Extension at Break 32

x

4.2.4 Stress-Strain Relationship 35

4.2.5 Tensile Modulus 39

4.2.6 Swelling 41

5 CONCLUSION AND RECOMMENDATION

5.1 Conclusion 44

5.2 Recommendation 45

REFERENCES 46

APPENDICES 49

xi

LIST OF TABLES

TABLE TITLE PAGE

3.1 Part per hundred Rubber Formulations 21

3.2 Ingredient weight value based on 250 grams per sample 22

3.3 Rubber Stages during Blending 23

3.4 Result available for rubber tensile test at Universal Tensile Machine 25

4.1 Result in tensile test 28

4.2 Result in swelling test 29

xii

LIST OF FIGURES

FIGURE TITLE PAGE

2.1 Oil palm trunk fiber 6

2.2 Tensile strength-rice husk content relationship (A.I. Khalf et al.,

2010) 8

2.3 Tensile strength of natural rubber reinforced with various fillers (N.

Rattanasom et al., 2009) 9

2.4 Tensile strength of rubber-filler content relationship (Hanafi Ismail

et al., 1996) 10

2.5

Tensile modulus of white rice husk ash loading in natural

rubber/linear low density polyethylene blends (Hanafi Ismail et al.,

2000)

11

2.6 Modulus at 100% elongation according to fiber loading (Hanafi

Ismail et al., 1999) 12

2.7 Swelling behavior of recycled rubber powder filler on natural rubber

(Hanafi Ismail et al., 2001) 13

2.8 Elongation at break versus fiber loading in sisal/oil palm hybrid

fiber reinforced natural rubber (Maya Jacob et al., 2003) 14

2.9

Horizontal profile of liquid axial velocity in downcomer for three

The tensile strength of SBR/NBRr with/without ENR-50 (Noriman

et al., 2009)

15

2.10 The tensile modulus of SBR/NBRr with/without ENR-50 (Noriman

et al., 2009) 15

2.11 Swelling behavior of natural rubber filled silica/carbon black (N.


xiii

2.12 100% modulus in silica content (N. Rattanasom et al., 2007) 17

2.13 Tensile strength of rubber-silica/carbon black relationship (N.


2.14

Modulus at 100% elongation versus filler content in natural

rubber/carbon black/calcium carbonate (Saowaroj Chuayjuljit et al.,

2002)

18

2.15 Tensile strength and elongation at break of natural

rubber/organoclay nanocomposite (P. L. Teh et al., 2003) 19

3.1 Two rolls mill 23

3.2 25-ton hot and cold molding press 24

3.3 50kN universal testing machine 26

4.1 Graph of time to break (sec) versus filler content (PHR) 30

4.2 Graph of highest tensile strength (MPa) versus filler content (PHR) 31

4.3 Tensile strength versus loading (PHR) of rice husk/ENR (Z. A. M.

Ishak et al., 1994) 32

4.4 Graph of extension (mm) versus filler content (PHR) 33

4.5 Elongation result from various contents of filler (Siti Salina Sarkawi

et al., 2003) 34

4.6 Stress-Strain relationship of 0 parts filler in SBR 35





4.11 Graph of tensile modulus (MPa) versus filler content (PHR) 40

4.12 Tensile modulus versus filler loading in oil palm wood flour/natural

rubber blend (Hanafi Ismail et al., 1999) 41

4.13 Graph of swelling (%) versus filler content (PHR) 42

4.14 Effect on swelling index in various filler (P.L. Teh et al., 2004) 43

xiv

LIST OF APPENDICES

APPENDIX TITLE PAGE

A Stress-Strain Result 49

B Technical Report 50

xv

LIST OF ABBREVIATIONS

SBR Styrene Butadiene Rubber

NR Natural Rubber

SMR Standard Malaysia Rubber

kN Kilo Newton

mm Millimetre

Sec Second

MPa Mega Pascal

PHR Part per hundred Rubber

CB Carbon Black

ENR Epoxidized Natural Rubber

6-PPD N-(1,3-dimethylbutyl)-N'-phenyl-p-phenylene-diamine)

CBS N-cyclohexyl-2-benzothiazyl sulphenamide

W Weight

μ Micro

°C Degree Celsius

N/cm2

Newton per Centimetre Square

g/cm3 Gram per Centimetre Cube

1

CHAPTER 1

INTRODUCTION

1.1 BACKGROUND OF STUDY

Rubber can be categorizes into two; natural rubber and synthetic rubber. Natural

rubber can be found in the form of latex, which is milky in color. The latex can be found

in typical rubber trees originally from South Africa. Rubber has the ability to undergo

plastic deformation and still can return to its previous form. This ability gives the rubber

advantages to be selected in many manufacturing product such as tire etc.



from natural rubber in every aspect. Styrene-butadiene rubber has low elasticity

properties; it is easy to cut and press compared to Standard Malaysian Rubber (SMR) –

natural rubber type of rubber.

Styrene-butadiene Rubber (SBR) is a polymer which combines copolymer of

styrene and butadiene to form whether 1,2-, cis-1,4-, or trans-1,4-unit components (Sung-

Seen Choi, 2001). Sung-Seen Choi also stated that styrene-butadiene rubber depend on

the component form, 1,2-, cis-1,4-, or trans-1,4-units to produce different microstructure.

Styrene-butadiene rubber is commonly used in tire compounds.

2

Oil palm trunk fiber can be found in oil palm tree that commonly plant in

Malaysia. Oil palm was brought into Malaysia from Botanical Garden, Singapore in 1870

(K. O. Lim et al., 1996). Oil palm trunk fiber can be use as a natural filler to produce

different properties to rubber.

1.2 PROBLEM STATEMENTS

Rubber is a special polymer with high tensile strength and low hardness. Rubber

take place in marketable as a good product such as tire, medical glove, slipper etc.

Different type of products needs different type of tensile strength as well as hardness.

Therefore, to reduce tensile strength and increase hardness, fillers are needed. Findik et

al., (2004) stated that fillers are reinforced into rubber mixture for better performance and

reducing cost.

Oil palm trees are trees with specialty to produce oil – usually to produce cooking

oil. The trees produce yields that decreasing every year, which leads to the tree being

replanted 25 – 30 years later after planting (K. O. Lim et al., 1996). The oil palm trunk

was treated as a waste and usually was burnt at plant location (H. Yamada et al., 2010).

The burning activities will led to environmental issues such as green house effect and

acid rain.

The purpose of this research is to investigate the properties of styrene butadiene

rubber blending with oil palm trunk fiber as filler. This research also carried out in order

to check significant of different parts of oil palm trunk fiber acting as filler used to

styrene butadiene rubber.

3

1.3 OBJECTIVES OF THE RESEARCH

There are two objectives that were carried out during this research after

considering the method and raw materials used.

To investigate the mechanical properties changes in styrene butadiene rubber

(SBR) filled with oil palm trunks as fillers.

To check the differences in properties between the amounts of fillers used.

1.4 SCOPE OF STUDY

The research is based on experimental lab research. Styrene butadiene rubber, oil

palm trunk fiber and other chemicals were ordered through chemical engineering

laboratory. The parts of oil palm trunk fiber that is going to be used are 0 parts, 15 parts,

30 parts, 40 parts and 50 parts. The blending was carried out at typical two rolls mill

located inside chemical engineering laboratory with speed 12 rotations per minute,

maximum temperature of 90 °C and minimum temperature 70°C. The molding process

was done using 25 ton hot and cold molding press located at chemical engineering

laboratory with maximum temperature of 165 °C and minimum temperature 155 °C.

The mechanical properties that being tests are tensile and swelling test. The

tensile test was done using 50 kN universal testing machine located at manufacturing

engineering laboratory. The parameter used in this test are Tensile strain at Break

(Standard) (mm/mm), Load at Break (Standard) (N), Extension at Break (Standard)

(mm), Tensile extension at Break (Standard) (mm), Time at Break (Standard) (sec), and

Modulus (Automatic) (MPa). Swelling test was done in chemical engineering laboratory

with only two chemical test; kerosene and diesel. The diesel that is being used is a typical

diesel that can be bought at petrol station.

4

1.5 RATIONALE AND SIGNIFICANCE

Different type of products needs different type of tensile strength as well as

hardness. Therefore, to reduce tensile strength and increase hardness, fillers are needed.

The compatibility of styrene butadiene rubber with oil palm trunk fiber was test to

determine the properties in them.

The oil palm trees produce yields that decreasing every year, which leads to the

tree being replanted 25 – 30 years later after planting (K. O. Lim et al., 1996). The oil

palm trunk was treated as a waste and usually was burnt at plant location (H. Yamada et

al., 2010). The contribution of oil palm trunk as a filler in rubber compound will decrease

the burning activities and reducing environmental issues.

5

CHAPTER 2

LITERATURE REVIEW

2.1 STYRENE BUTADIENE RUBBER



from natural rubber in every aspect. Styrene-butadiene rubber has low elasticity

properties; it is easy to cut and press compared to Standard Malaysian Rubber (SMR) –

natural rubber type of rubber.

Styrene-butadiene Rubber (SBR) is a polymer which combines copolymer of

styrene and butadiene to form whether 1,2-, cis-1,4-, or trans-1,4-unit components (Sung-

Seen Choi, 2001). Sung-Seen Choi also stated that styrene-butadiene rubber depend on

the component form, 1,2-, cis-1,4-, or trans-1,4-units to produce different microstructure.

Styrene-butadiene rubber is commonly used in tire compounds.

M.T. Ramesan et al., (2004) reported that blending of natural rubber/styrene

butadiene rubber gives better abrasion resistance properties. This is proven that styrene

butadiene rubber give boost to natural rubber in term of properties and good.

6

2.2 NATURAL FILLER

Many researches have been done in rubber/natural filler blending in order to

improve the properties of rubber with economically. Natural filler that usually being used

in research are rise husk, oil palm fiber and coconut fiber. The differences in properties of

rubber product can be obtained from different filler.

2.3 OIL PALM TRUNK FIBER

Oil palm trunk fiber can be found in oil palm tree that commonly plant in

Malaysia. Oil palm was brought into Malaysia from Botanical Garden, Singapore in 1870

(K. O. Lim et al., 1996). Oil palm trunk fiber can be use as a natural filler to produce

different properties to rubber.

Figure 2.1: Oil palm trunk fiber.

7

RunCang Sun et al., (2001) reported that the oil palm trunk fiber enhance sulphate

pulp properties into fair strength. Oil palm trunk fiber can be potential in increasing

properties of rubber as filler. The cooperation of oil palm trunk fiber and styrene

butadiene rubber might enhance the rubber properties.

2.4 CROSSLINK

Rubber processing is a must to mix rubber and filler into one, solid rubber

product. Vulcanizing agent is a part of crosslink between rubber bonds. Fillers is

reinforced into rubber mixture for better performance and reducing cost (Findik et al.,

2004). Findik et al., (2004) also stated that, sulphur and peroxide are two common

vulcanizing agents that used activation energy which increase the mechanical properties

of rubber product at higher temperature.

2.5 VULCANIZATION

Vulcanization is a process where the rubber matrix is being crosslink with help

from vulcanizing agents. After being vulcanized, the rubber compound became cured;

with no more reaction happen causing the rubber became stable. The curing happens at

high temperature within 150 – 170 °C according to their rubber properties respectively.

Popular vulcanizing agents used are sulphur and peroxide.

8

2.6 MECHANICAL PROPERTIES

2.6.1 TENSILE STRENGTH

Many researches have been done in order to investigate the mechanical properties

of rubber and natural fillers before. A.I. Khalf et al., (2010) have investigated the effect

of rice husk filler in styrene butadiene rubber with the presence of maleic anhydride. The

tensile strength of rubber sample increase until 25 PHR of filler content, before it start to

decrease at 30 PHR. This is because of the high content of filler that may cause the poor

bonding in rubber matrix causing the tensile strength to drop.

Figure 2.2: Tensile strength-rice husk content relationship (A.I. Khalf et al., 2010).

9

N. Rattanasom et al., (2009) on the other hand have investigated the mechanical

properties of natural rubber reinforced with various fillers. Gum is virgin rubber, C6 is

addition of 6 PHR of clay, CB6 is addition of 6 PHR of carbon black, CB14 is addition of

14 PHR of carbon black, S6 is addition of 6 PHR of silica and S35 is addition of 35 PHR

of silica. Clay in 6 PHR quantity show promising aspect in tensile strength than the other.

Figure 2.3: Tensile strength of natural rubber reinforced with various fillers (N.

Rattanasom et al., 2009).

Hanafi Ismail et al., (1996) also have investigated the mechanical properties of

ENR/oil palm wood flour. The tensile strength of rubber decreases with increasing of

filler content and filler size.

10

Figure 2.4: Tensile strength of rubber-filler content relationship (Hanafi Ismail et al.,

1996)

2.6.2 TENSILE MODULUS

Many researches have been done to determine the tensile modulus of rubber

compound. In order to check the compatibility of rubber composite, the modulus is

defined in the stress-strain relationship. Hanafi Ismail et al., (2000) have determined the

tensile modulus of white rice husk ash loading in natural rubber/linear low density

polyethylene blends with proportional to filler content. The additions of natural filler

basically increase tensile modulus of the rubber compound.

11

Figure 2.5: Tensile modulus of white rice husk ash loading in natural rubber/linear low

density polyethylene blends (Hanafi Ismail et al., 2000).

Hanafi Ismail et al., (1999) have investigated the mechanical properties of rubber

reinforced short oil palm fiber. The tensile modulus for treated rubber compound is much

better than the untreated one. This is because of vulcanization process enhance the rubber

properties causing the tensile modulus to increase more than untreated one.

12

Figure 2.6: Modulus at 100% elongation according to fiber loading (Hanafi Ismail et al.,

1999).

2.6.3 SWELLING

Swelling behavior is the ability of the rubber product to absorb chemical.

Swelling test was done in order to check chemical resistance in rubber sample. Many

researches have been done according to swelling behavior. Hanafi Ismail et al., (2001)

have investigated the swelling behavior of recycled rubber powder filler on natural

rubber. The more filler give more chemical resistance. As the natural rubber was filled,

the rubber became more stable and increase chemical resistance ability and less chemical

can be absorb.

13

Figure 2.7: Swelling behavior of recycled rubber powder filler on natural rubber (Hanafi

Ismail et al., 2001).

2.6.4 ELONGATION

Elongation before break is determined to check the ability of rubber to extend

their length before break. Many researches have been done in order to determine this

property. Maya Jacob et al., (2003) have investigated the mechanical properties of sisal

and oil palm hybrid fiber reinforced with natural rubber. The elongation became shorter

as the filler content increase. This is because of brittleness of rubber sample increase with

increasing of filler loading.

14

Figure 2.8: Elongation at break versus fiber loading in sisal/oil palm hybrid fiber

reinforced natural rubber (Maya Jacob et al., 2003).

2.7 RECYCLED ELASTOMER

Recycling elastomer and converted it to reinforce with rubber proven economical

as the filler is already in the recycled elastomer. Various researches have been done in

order to determine recycled elastomer as filler properties. Noriman et al., (2009) has

investigated the mechanical properties of styrene butadiene rubber (SBR) reinforced with

recycled acrylonitrile-butadiene rubber (NBRr) assisted by epoxidized natural rubber

(ENR-50). The tensile strength has increased with decreasing of NBRr composition but

the existence of ENR-50 improved the property.

15

Figure 2.9: The tensile strength of SBR/NBRr with/without ENR-50 (Noriman et al.,

2009).

Figure 2.10: The tensile modulus of SBR/NBRr with/without ENR-50 (Noriman et al.,

2009).

16

2.8 CARBON BLACK FILLER

Carbon black is one of the fillers that often being used in tire production. Many

researches has been done in order to improve rubber properties by using carbon black,

although it has been proven in tire-strength and hardness increase to support vehicle. N.

Rattanasom et al., (2007) has investigated the mechanical properties of silica/carbon

black dual filler in natural rubber. The swelling ratio increase a little with increasing of

filler content. This is because of silica is not a good filler as it increase chemical

absorption ability in rubber compound.

Figure 2.11: Swelling behavior of natural rubber filled silica/carbon black (N.

Rattanasom et al., 2007)

As for tensile and modulus, the silica/carbon black fillers increase tensile strength

while reduces the modulus. This is because of reducing in crosslink density when silica

content is high in the rubber compound.

17

Figure 2.12: 100% modulus in silica content (N. Rattanasom et al., 2007).

Figure 2.13: Tensile strength of rubber-silica/carbon black relationship (N. Rattanasom et

al., 2007).

18

Saowaroj Chuayjuljit et al., (2002) on the other hand have investigated the natural

rubber filled with carbon black and calcium carbonate. The modulus at 100% elongation

increase as the filler content increase because of chain in rubber compound has became

tighten with existence of carbon black.

Figure 2.14: Modulus at 100% elongation versus filler content in natural rubber/carbon

black/calcium carbonate (Saowaroj Chuayjuljit et al., 2002).

19

2.9 ORGANOCLAY

P. L. Teh et al., (2003) has investigated the natural rubber filled with organoclay

nanocomposite. The tensile strength and elongation at break increase until 2 PHR of filler

content, before dropping until 10 PHR. This is showed that the filler content until 2 PHR

increase the properties of rubber compound but increasing filler content any further will

resulting in low properties of rubber compound.

Figure 2.15: Tensile strength and elongation at break of natural rubber/organoclay

nanocomposite (P. L. Teh et al., 2003).

20

CHAPTER 3

METHODOLOGY

3.1 CHEMICAL AND APPARATUS

CHEMICAL APPARATUS

Styrene Butadiene Rubber Two Rolls Mill

Stearic Acid Hot and Cold Molding Press

Zinc Oxide Universal Testing Machine

6-PPD

CBS

Sulphur

Oil Palm Trunks Fiber

Diesel

Kerosene

21

3.2 RUBBER FORMULATION

Rubber compounding depends on part per hundred rubber formulations by taking

rubber as 100 parts. The rubber formulations taking into consider is shown in Table 3.1

below, with filler – Oil Palm Trunk Fiber as variables raw material.

Table 3.1: Part per hundred Rubber Formulations.

Ingredient Formulation (Part per hundred)

1 2 3 4 5

SBR 100 100 100 100 100

Stearic Acid 2 2 2 2 2

Zinc Oxide 5 5 5 5 5

6-PPDa 1 1 1 1 1

CBSb 0.5 0.5 0.5 0.5 0.5

Sulphur 2.5 2.5 2.5 2.5 2.5

Fillerc 0 15 30 40 50

Total 111 126 141 151 161

a N-(1,3-dimethylbutyl)-N'-phenyl-p-phenylene-diamine)

b N-cyclohexyl-2-benzothiazyl sulphenamide

c Oil Palm Trunk Fiber

After figuring part per hundred rubbers compounding that are going to be blend,

the exact value of weight are calculated based on 250 grams per sample produced. The

data calculated are tabulate in Table 3.2 below. As filler parts increase, the weights of the

filler also increase causing the weight of SBR decrease.

22

𝑊 =𝑃𝐻𝑅

𝑇𝑜𝑡𝑎𝑙 𝑃𝐻𝑅× 250

Where;

W = Weight of chemical in 250 grams rubber sample

PHR = Parts per hundred rubber formulation

Table 3.2: Ingredient weight value based on 250 grams per sample.

Ingredient Weight (grams)

1 2 3 4 5

SBR 225.23 198.41 177.30 165.56 155.28

Stearic Acid 4.50 3.97 3.55 3.31 3.11

Zinc Oxide 11.26 9.92 8.87 8.28 7.76

6-PPDa 2.25 1.98 1.77 1.66 1.55

CBSb 1.13 0.99 0.89 0.83 0.78

Sulphur 5.63 4.96 4.43 4.14 3.88

Fillerc 0.00 29.76 53.19 66.23 77.64

Total 250.00 250.00 250.00 250.00 250.00

a N-(1,3-dimethylbutyl)-N'-phenyl-p-phenylene-diamine)

b N-cyclohexyl-2-benzothiazyl sulphenamide

c Oil Palm Trunk Fiber

3.3 SIEVING

The oil palm trunk fiber came in the form of clog. The powder resides inside the

clog is needed in order to proceed into next stage-blending. Therefore, it is a must to

sieve the clog before weighing it and blend. The sieving work was done manually by

using 400μ sieve to recover oil palm trunk powder.

23

3.4 BLENDING

Two rolls mill is used as an equipment to blend. The SBR were blend in three

stages; filler addition, activator addition and vulcanizing agent/accelerator addition.

Table 3.3: Rubber Stages during Blending.

Stage 1 Stage 2 Stage 3

Filler Zinc oxide Sulphur

- Stearic acid CBS

- 6-PPD -

The rubber is blend slowly to make sure the blending is well homogenous. During

rubber blending, the heater was switched on to enhance the rubber blending, as SBR

became much easier to form as sheet during heating. The temperature was set to 80 °C

and the speed that being used is only 12 rotations per minute. Stage 1 required filler – Oil

Palm Trunk Fiber to blend. As the filler parts increase, SBR parts decrease due to fixed

value of rubber formulation which is 250 grams per sample.

Figure 3.1: Two rolls mill.

24

Stage 3 was a little different than other stages. This is because the sample with

activator addition needs to be left to cold down before adding vulcanizing agent and

accelerator. Vulcanizing agent is blend in this stage as the vulcanization will cure the

rubber compound and the rubber is no longer can be blend afterwards.

3.5 MOLDING

As the rubber blending process finish, the process continue to molding in 25 ton

hot and cold molding press to form a fixed sheet of rubber compound. The sample were

cut into half and pressed in hot and cold molding press. The temperature of hot and cold

molding press is set at 160 °C for each plate. The sample were then left for 15 minutes as

SBR burn easily to be left under long period.

Figure 3.2: 25-Ton hot and cold molding press.

25

3.6 TENSILE TEST

Tensile test was done in order to check the improvement of sample from 0 parts

until 50 parts oil palm trunk fiber. 50 kN universal tensile machine was used during the

test.

Table 3.4: Result available for rubber tensile test at Universal Tensile Machine

No. Result Available

1. Tensile strain at Break (Standard) (mm/mm)

2. Load at Break (Standard) (N)

3. Extension at Break (Standard) (mm)

4. Tensile extension at Break (Standard) (mm)

5. Time at Break (Standard) (sec)

6. Modulus (Automatic) (MPa)

The results available for rubber testing were shown in Table 3.4 above. Tensile

test results were carried out in computer next to universal tensile machine.

26

Figure 3.3: 50 kN Universal testing machine.

3.7 SWELLING TEST

Two chemical used in this swelling test; kerosene and diesel. The samples were

cut into 2 pieces each and their weight was taken and recorded. After that, the samples

were put into two different bottles with kerosene inside one bottle and diesel inside

another bottle. The time taken to complete the test was 24 hours – exactly one day. The

samples were taken out and dry then at room temperature before weighing again.

27

3.8 PRECAUTION STEPS

Rubber processing used a lot of heating process and dangerous equipments. Two

rolls mill used heating process up to 80 °C and the temperature is not stable at one time.

The temperature can rise up to 100 °C unconsciously. Therefore, the temperature switch

needs to be turned off after reaching 80 °C and turned on back after drop to 75 °C. Two

rolls mill consist of two rollers rolling into each other and can crash finger if not carefully

blending samples. Therefore, no gloves are required to perform this process as the glove

can stuck inside rollers.

Hot and cold molding on the other hand needs heating up until 160 °C. There is

no way human can survive that temperature. Therefore, glove is a must wear safety

equipment as temperature resistance to skin.

28

CHAPTER 4

RESULT AND DISCUSSION

4.1 RESULT

4.1.1 TENSILE TEST

Table 4.1: Result in tensile test.

Filler Content

(PHR)

Time to break

(Sec)

Highest Tensile Strain

(MPa)

Extension

(mm)

0 132.93 0.58 44.31

15 103.00 0.84 34.36

30 67.34 0.77 22.45

40 40.50 0.71 13.52

50 33.55 0.65 10.48

𝐸𝑥𝑡𝑒𝑛𝑠𝑖𝑜𝑛 = 𝐿𝑜𝑛𝑔𝑒𝑠𝑡 − 𝑆𝑕𝑜𝑟𝑡𝑒𝑠𝑡

29

4.1.2 SWELLING TEST

Table 4.2: Result in swelling test.

Filler Content

(PHR)

Kerosene Diesel

Before

(gram)

After

(gram)

Swelling

(%)

Before

(gram)

After

(gram)

Swelling

(%)

0 0.63 1.54 144.44 0.73 1.64 124.66

15 0.47 1.33 182.98 0.52 0.94 80.77

30 0.41 1.10 168.29 0.34 0.94 176.47

40 1.22 2.75 125.41 1.22 2.06 68.85

50 0.57 1.62 184.21 0.52 1.13 117.31

𝑆𝑤𝑒𝑙𝑙𝑖𝑛𝑔 =𝐴𝑓𝑡𝑒𝑟 − 𝐵𝑒𝑓𝑜𝑟𝑒

𝐵𝑒𝑓𝑜𝑟𝑒× 100%

30

4.2 DISCUSSION

4.2.1 TIME TO BREAK

Figure 4.1 below shows the relationship of time take to break the rubber sample

into two against filler content. Increasing of filler quantities affect the time to break as the

time show decreasing value, showing that the sample became more brittle with addition

of fillers. This is because, increasing of filler content into rubber reduce its plasticity in

chain (Hanafi Ismail et al., 1998). The plasticity of rubber chain decrease because of the

SBR is force to receive high quantity of filler, despite of their small quantity in number.

Figure 4.1: Graph of time to break (sec) versus filler content (PHR).

0

20

40

60

80

100

120

140

0 10 20 30 40 50 60

Tim

e t

o B

rea

k (

Sec)

Filler Content (PHR)

31

4.2.2 TENSILE STRENGTH

Figure 4.2 below shows that the highest value tensile strength (MPa) against the

filler content. From 0 parts to 15 parts, the value of tensile strength increases and

decreases after 15 parts onwards. This is show that the best tensile strength values lay on

15 parts of filler content, and any filler addition afterward will reduce its tensile

properties.

Figure 4.2: Graph of highest tensile strength (MPa) versus filler content (PHR).

Z. A. M. Ishak et al., (1994) have investigated the mechanical properties of rice

husk filler in epoxidized natural rubber (ENR). In overall, the tensile strength decreases,

with the increasing of filler content. The best tensile strength will be at 20 PHR filler

content, which mean the limit of ENR exceed after adding filler more than 20 PHR,

resulting in poor tensile strength properties.

0

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8

0.9

0 10 20 30 40 50 60

Hig

hes

t T

ensi

le S

tren

gth

(M

Pa

)


32

Figure 4.3: Tensile strength versus loading (PHR) of rice husk/ENR (Z. A. M. Ishak et

al., 1994).

Comparing the result in this research with previous study, the tensile properties of

rubber reinforced with natural filler did increase the tensile strength at some point, before

dropping again. This is explained why the tensile strength of styrene butadiene rubber

filled with oil palm trunk fiber increase at 15 PHR of filler content but decrease

afterwards until 50 PHR of filler content.

4.2.3 EXTENSION AT BREAK

Figure 4.4 below show the relationship of extension of rubber sample before

break against the filler content. The extension became shorter after adding more filler

content. The additions of filler remove rubber elasticity and increase brittleness of rubber

product.

33

Figure 4.4: Graph of extension (mm) versus filler content (PHR).

This is expected as the filling of filler in rubber matrix causing the plasticity of

rubber chain decrease, increasing the brittleness of rubber product as well as decreasing

their elasticity. The gap in rubber matrix is filled with non-elastic filler; reduce its

elasticity more with addition more of filler content.

Siti Salina Sarkawi et al., (2003) have investigated ground rice husk in rubber

compounding. From the result, elongation of rubber compound has increase at 10 PHR

rice husk as filler content but decrease after adding more filler content inside. This is

happened because of blending error; the filler might not disperse well during blend.

0

5

10

15

20

25

30

35

40

45

50

0 10 20 30 40 50 60

Exte

nsi

on

(m

m)


34

Figure 4.5: Elongation result from various contents of filler (Siti Salina Sarkawi et al.,

2003).

From both results, this research and previous study, the elongation at break is

cause by filler loading. The more filler is put inside; the rubber became more brittle and

easy to break. This is due to the tight bonding of rubber compound, making it more brittle

for each addition of filler contents.

35

4.2.4 STRESS-STRAIN RELATIONSHIP

Figure 4.6 shows the stress-strain relationship in rubber product consist of 0 parts

of filler – no filler inside. The virgin SBR is reinforced with chemical only, and SBR

quantity is 225.23 gram per 250 gram sample.

Figure 4.6: Stress-Strain relationship of 0 parts filler in SBR.

The maximum stress is about 30 N/cm2 at strain is about 0.65. The straight line

graph was plotted inside the graph to determine the value of gradient – tensile modulus.

The straight line intercept at stress = 14.194 N/cm2 and gradient = 13.137.

y = 13.13x + 14.19

-15

-10

-5

0

5

10

15

20

25

30

35

0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8

Str

ess

(N/c

m2

)

Strain

36

Figure 4.7 shows the stress-strain relationship in rubber product consist of 15

parts of filler – oil palm trunk fiber. The SBR quantity is 198.41 gram per 250 gram

sample and the quantity of filler is 29.76 gram per 250 gram sample.


The maximum stress is about 60 N/cm2 at strain is about 0.2 - 0.3. The straight

line graph was plotted inside the graph to determine the value of gradient – tensile

modulus. The straight line intercept at stress = 42.75 N/cm2 and gradient = 13.357.

y = 13.35x + 42.75

-10

0

10

20

30

40

50

60

70

0 0.1 0.2 0.3 0.4 0.5 0.6

Str

ess

(N/c

m2

)

Strain

37








y = 7.300x + 49.04

-10

0

10

20

30

40

50

60

70

80

0 0.05 0.1 0.15 0.2 0.25 0.3 0.35 0.4

Str

ess

(N/c

m2

)

Strain

38







The straight line intercept at stress = 53.521 N/cm2 and gradient = -33.623.

y = -33.62x + 53.52

-10

0

10

20

30

40

50

60

70

80

0 0.05 0.1 0.15 0.2 0.25

Str

ess

(N/c

m2

)

Strain

39








4.2.5 TENSILE MODULUS

Figure 4.11 show the relationship of tensile modulus (MPa) against filler content.

The value of tensile modulus was determined from graph stress-strain relationship by

drawing straight line and gradient calculate from it.

y = 57.89x + 40.75

-10

0

10

20

30

40

50

60

70

0 0.05 0.1 0.15 0.2

Str

ess

(N/c

m2

)

Strain

40

Figure 4.11: Graph of tensile modulus (MPa) versus filler content (PHR).

The values of tensile modulus increase from 0 parts until 15 parts and drop at 30

parts. The values then rapidly drop at 40 parts before increase rapidly at 50 parts. The

value of tensile modulus decrease rapidly must be because of an error during test. The

sample might have crack earlier than expected after load was applied causing the value of

load decrease rapidly after that.

Hanafi Ismail et al., (1999) have investigated the mechanical properties of natural

rubber/oil palm wood flour composites. The tensile modulus increases with the increasing

of filler loading in rubber composites. This is because the increasing of stress over strains

which resulting in high tensile modulus result.

-40

-20

0

20

40

60

80

0 10 20 30 40 50 60Ten

sile

Mo

du

lus

(MP

a)


41

Figure 4.12: Tensile modulus versus filler loading in oil palm wood flour/natural rubber

blend (Hanafi Ismail et al., 1999).

Comparing the result obtained in this research and previous study, the tensile

modulus is totally different. Perhaps it is cause by different rubber – which led to

different properties.

4.2.6 SWELLING

Figure 4.13 show the relationship of chemical absorption in sample. The graph

was plot in two series; kerosene and diesel.

42

Figure 4.13: Graph of swelling (%) versus filler content (PHR).

The maximum absorption of kerosene in rubber sample is at 50 parts of filler

content. This is because the filler is hydrophilic – ability to absorb. The more filler

content mean the more hydrophilic area – which is why high quantity of kerosene can be

absorb at high quantity of filler.

The maximum absorption of diesel in rubber sample is at 30 parts of filler

content. The value seems to vary and high at middle point because of the error while

preparing the sample. Rubber sample area must be large at 30 parts, causing it to absorb

more diesel than the others.

In overall, rubber sample absorb kerosene much better than diesel. This is because

of low density of kerosene - 0.78–0.81 g/cm3 compared to diesel – 0.832 g/cm

3.

P.L. Teh et al., (2004) have investigated the organoclay/(carbon black/silica)

addition in epoxidized natural rubber/natural rubber vulcanized. From the result, virgin

rubber vulcanized has more tendencies to absorb more chemical than rubber reinforced

filler. The addition of filler increase chemical resistance property of rubber compound.

0

20

40

60

80

100

120

140

160

180

200

0 10 20 30 40 50 60

Sw

elli

ng

(%

)


Kerosene

Diesel

43

Figure 4.14: Effect on swelling index in various filler (P.L. Teh et al., 2004).

By comparing this research and previous study, this research provides result with

many errors. The addition of filler should provide more chemical resistance. This result

perhaps comes from error in blending – the filler is not fully dispersed.

44

CHAPTER 5

CONCLUSION AND RECOMMENDATION

5.1 CONCLUSION

From the result obtained, time to break, tensile strength and extension decrease as

the filler content decrease. This is because of the stiffness and brittleness of rubber

sample increase with increasing of filler content. The young modulus also increases with

increasing of filler content, as the load over area increase and the elongation decrease.

The swelling test indicated that kerosene is being absorbed much better in rubber

sample than diesel. This is because of low density of kerosene, compared to diesel.

The comparison of various studies has showed that, the result obtained from this

research has many errors. This is maybe causing from improper way of processing or

handling which cause the result to unexpectedly do not show similarity to previous study.

From result, the tensile strength decrease with increasing of filler content. The

tensile modulus increase as well as the chemical absorption increase with increasing of

filler content.

45

5.2 RECOMMENDATION

The result obtained is not well enough. This is because of the machinery problem

as well as the filler content. The equipment used in this research is time consuming

machinery – one sample take a long time to finish blending. The filler content is different

for every sample – causing it to take long time as the filler content increase.

The equipments need to be change into something that can blend faster, and

reducing time to prepare one sample.

The result obtained from five samples is not enough to make sure that the

properties does change. Increasing the filler content might give the better result, and

giving more information about capability of styrene butadiene rubber to consume more

filler.

46

REFERENCES

A.I. Khalf, & A.A. Ward (2010). Use of rice husks as potential filler in styrene butadiene

rubber/linear low density polyethylene blends in the presence of maleic

anhydride, Materials and Design, 31, 2414–2421

F. Findik, R. Yilmaz, & T. Köksal (2004). Investigation of mechanical and physical

properties of several industrial rubbers, Material and Design, 25, 269-276

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swelling behaviour of recycled rubber powder-filled natural rubber compounds,

Polymer Testing, 21, 565–569

H. Yamada, R. Tanaka, O. Sulaiman, R. Hashim, Z.A.A. Hamid, M.K.A. Yahya, A.

Kosugi, T. Arai, Y. Murata, S. Nirasawa, K. Yamamoto, S. Ohara, Mohd Nor

Mohd Yusof, Wan Asma Ibrahim, & Y. Mori (2010). Old oil palm trunk: A

promising source of sugars for bioethanol production, Biomass and Bioenergy,

34, 1608-1613

Hanafi Ismail, H. D. Rozman, R. M. Jaffri, & Z. A. Mohd Ishak (1997). Oil palm wood

flour reinforced epoxidized natural rubber composites: the effect of filler content

and size, Eur. Polym. 1. Vol. 33, No. 10-12, pp. 1627-1632

Hanafi Ismail, J.M. Nizam, & H.P.S. Abdul Khalil (2001). The effect of a compatibilizer

on the mechanical properties and mass swell of white rice husk ash filled natural

rubber/linear low density polyethylene blends, Polymer Testing, 20, 125–133

Hanafi Ismail, N. Rosnah & H. D. Rozman (1997). Curing characteristics and

mechanical properties of short oil palm fibre reinforced rubber composites,

Polymer Vol. 38 No. 16, PP. 4059-4064

47

Hanafi Ismail, & R.M. Jaffri (1999). Physico-mechanical properties of oil palm wood

flour filled natural rubber composites, Polymer Testing, 18, 381-388

K. O. Lim, Faridah Hanum Ahmaddin, & S. Malar Vizhi (1997). A note on the

conversion of oil-palm trunks to glucose via acid hydrolysis, Bioresource

Technology, 59, 33-35

Maya Jacob, Sabu Thomas, & K.T. Varughese (2004). Mechanical properties of sisal/oil

palm hybrid fiber reinforced natural rubber composites, Composites Science and

Technology, 64, 955–965

M.T. Ramesan, Rosamma Alex, & N.V. Khanh (2005). Studies on the cure and

mechanical properties of blends of natural rubber with dichlorocarbene modified

styrene–butadiene rubber and chloroprene rubber, Reactive & Functional

Polymers, 62, 41–50

N. Rattanasom, S. Prasertsri, & T. Ruangritnumchai (2009). Comparison of the

mechanical properties at similar hardness level of natural rubber filled with

various reinforcing-fillers, Polymer Testing, 28, 8–12

N. Rattanasom, T. Saowapark, & C. Deeprasertkul (2007). Reinforcement of natural

rubber with silica/carbon black hybrid filler, Polymer Testing, 26, 369–377

N.Z. Noriman, H. Ismail, & A.A. Rashid (2010). Characterization of styrene butadiene

rubber/recycled acrylonitrile-butadiene rubber (SBR/NBRr) blends: The effects of

epoxidized natural rubber (ENR-50) as a compatibilizer, Polymer Testing, 29,

200–208

RunCang Sun, & J. Tomkinson (2001). Fractional separation and physico-chemical

analysis of lignins from the black liquor of oil palm trunk fibre pulping,

Separation and Purification Technology, 24, 529–539

P. L. Teh, Z. A. Mohd Ishak, A. S. Hashim, J. Karger-Kocsis, & U. S. Ishiaku (2004). On

the potential of organoclay with respect to conventional fillers (carbon black,

48

silica) for epoxidized natural rubber compatibilized natural rubber vulcanizates,

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characteristics and mechanical properties of natural rubber/organoclay

nanocomposites, Jurnal Teknologi, 39(A) Keluaran Khas. Dis. 2003: 1–10

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(2002). Effects of Particle Size and Amount of Carbon Black and Calcium

Carbonate on Curing Characteristics and Dynamic Mechanical Properties of

Natural Rubber, Journal of Metals, Materials and Minerals. Vol. 12 No. 1 pp. 51-

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compounding, Jurnal Teknologi, 39(A) Keluaran Khas. Dis. 2003: 135–148

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rubbers with differing microstructures, Journal of Analytical and Applied

Pyrolysis, 62, 319–330

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as fillers for epoxidized natural rubber (ENR), Eur. Pol~nt. J. Vol. 31, No. 3, pp.

259-26

49

APPENDIX

A. STRESS-STRAIN RESULT

50

B. TECHNICAL REPORT

Mechanical Properties of Styrene Butadiene Rubber with Oil Palm Trunk Fiber as

Filler

Mohd Hazizul, Mohd Bijarimi*

Faculty of Chemical Engineering and Natural Resources

*Contact: [email protected]

Abstract

The objectives of this research are to investigate the mechanical properties changes in styrene butadiene rubber (SBR) filled with oil palm trunks as fillers and to check the differences in properties between the amounts of fillers used. The purpose of this research is

to investigate the properties of styrene butadiene rubber blending with oil palm trunk fiber as filler. The research is based on

experimental lab research. The result from testing showed that increasing amount of fillers will actually decrease the tensile strength, increase the tensile modulus and increase swelling behavior of the rubber blend.

Keywords: Styrene butadiene rubber, oil palm trunk fiber, tensile strength, tensile modulus, swelling behavior

Abstrak

Tujuan kajian ini adalah untuk mengetahui perubahan sifat mekanik dalam getah stirena butadiena (SBR) yang diisi dengan

batang kelapa sawit sebagai suapan dan untuk menyemak perbezaan sifat antara jumlah suapan digunakan. Tujuan dari penelitian ini

adalah untuk mengetahui sifat-sifat campuran getah stirena butadiena dengan serat batang kelapa sawit sebagai suapan. Penelitian ini

berdasarkan pada penelitian ujikaji makmal. Hasil dari ujian menunjukkan bahawa peningkatan jumlah suapan benar-benar akan

menurunkan kekuatan tarik, meningkatkan modulus tarik dan meningkatkan perilaku pembengkakan getah campuran.

Kata kunci: Getah stirena butadiena, serat batang kelapa sawit, kekuatan tarik, modulus tarik, perilaku bengkak

1.0 Introduction

Styrene-butadiene Rubber (SBR) is a

polymer which combines copolymer of styrene

and butadiene to form whether 1,2-, cis-1,4-, or

trans-1,4-unit components (Sung-Seen Choi,

2002). Sung-Seen Choi also stated that styrene-

butadiene rubber depend on the component form,

1,2-, cis-1,4-, or trans-1,4-units to produce

different microstructure. Styrene-butadiene

rubber is commonly used in tire compounds.

Oil palm trunk fiber can be found in oil

palm tree that commonly plant in Malaysia. Oil

palm was brought into Malaysia from Botanical

Garden, Singapore in 1870 (K. O. Lim et al.,

1997). Oil palm trunk fiber can be use as a

natural filler to produce different properties to

rubber.

The purpose of this research is to investigate

the properties of styrene butadiene rubber

blending with oil palm trunk fiber as filler. This

research also carried out in order to check

significant of different parts of oil palm trunk

fiber acting as filler used to styrene butadiene

rubber.

There are two objectives that were carried

out during this research after considering the

method and raw materials used.

To investigate the mechanical

properties changes in styrene butadiene

rubber (SBR) filled with oil palm trunks

as fillers.

To check the differences in properties

between the amounts of fillers used.

The oil palm trees produce yields that

decreasing every year, which leads to the tree

being replanted 25 – 30 years later after planting

(K. O. Lim et al., 1997). The oil palm trunk was

treated as a waste and usually was burnt at plant

location (H. Yamada et al., 2010). The

contribution of oil palm trunk as a filler in rubber

51

compound will decrease the burning activities

and reducing environmental issues.

RunCang Sun et al., (2001) reported that the

oil palm trunk fiber enhance sulphate pulp

properties into fair strength. Oil palm trunk fiber

can be potential in increasing properties of

rubber as filler.

Fillers are reinforced into rubber mixture for

better performance and reducing cost (Findik et

al., 2004). Findik et al., (2004) also stated that,

sulphur and peroxide are two common

vulcanizing agents that used activation energy

which increase the mechanical properties of

rubber product at higher temperature.

A.I. Khalf et al., (2010) have investigated

the effect of rice husk filler in styrene butadiene

rubber with the presence of maleic anhydride.

The tensile strength of rubber sample increase

until 25 PHR of filler content, before it start to

decrease at 30 PHR. This is because of the high

content of filler that may cause the poor bonding

in rubber matrix causing the tensile strength to

drop.

N. Rattanasom et al., (2009) on the other

hand have investigated the mechanical properties

of natural rubber reinforced with various fillers.

Gum is virgin rubber, C6 is addition of 6 PHR of

clay, CB6 is addition of 6 PHR of carbon black,

CB14 is addition of 14 PHR of carbon black, S6

is addition of 6 PHR of silica and S35 is addition

of 35 PHR of silica. Clay in 6 PHR quantity

show promising aspect in tensile strength than

the other.

Hanafi Ismail et al., (1997) have investigated the

mechanical properties of ENR/oil palm wood

flour. The tensile strength of rubber decreases

with increasing of filler content and filler size.

Hanafi Ismail et al., (2001) also have

determined the tensile modulus of white rice

husk ash loading in natural rubber/linear low

density polyethylene blends with proportional to

filler content. The additions of natural filler

basically increase tensile modulus of the rubber

compound.

Hanafi Ismail et al., (1997) have

investigated the mechanical properties of rubber

reinforced short oil palm fiber. The tensile

modulus for treated rubber compound is much

better than the untreated one. This is because of

vulcanization process enhance the rubber

properties causing the tensile modulus to

increase more than untreated one.

H. Ismail et al., (2002) have investigated the

swelling behavior of recycled rubber powder

filler on natural rubber. The more filler give

more chemical resistance. As the natural rubber

was filled, the rubber became more stable and

increase chemical resistance ability and less

chemical can be absorb.

Maya Jacob et al., (2004) have investigated

the mechanical properties of sisal and oil palm

hybrid fiber reinforced with natural rubber. The

elongation became shorter as the filler content

increase. This is because of brittleness of rubber

sample increase with increasing of filler loading.

2.0 Methodology

2.1. Chemical and equipment

Styrene butadiene rubber, oil palm trunk

fiber and other chemicals were ordered through

chemical engineering laboratory. The blending

was carried out at typical two rolls mill located

inside chemical engineering laboratory with

speed 12 rotations per minute, maximum

temperature of 90 °C and minimum temperature

70°C. The molding process was done using 25

ton hot and cold molding press located at

chemical engineering laboratory with maximum

temperature of 165 °C and minimum temperature

155 °C. The mechanical properties that being

tests are tensile and swelling test. The tensile test

was done using 50 kN universal testing machine

located at manufacturing engineering laboratory.

Swelling test was done in chemical engineering

laboratory with only two chemical test; kerosene

and diesel. The diesel that is being used is a

typical diesel that can be bought at petrol station.

2.2. Rubber Formulation

Ingredient Formulation (Part per

hundred)

1 2 3 4 5

SBR 100 100 100 100 100

Stearic

Acid

2 2 2 2 2

Zinc Oxide 5 5 5 5 5

6-PPDa 1 1 1 1 1

CBSb 0.5 0.5 0.5 0.5 0.5

Sulphur 2.5 2.5 2.5 2.5 2.5

Fillerc 0 15 30 40 50

Total 111 126 141 151 161 a N-(1,3-dimethylbutyl)-N'-phenyl-p-phenylene-

52

diamine) b N-cyclohexyl-2-benzothiazyl sulphenamide c Oil Palm Trunk Fiber

Table 2.1: Part per hundred Rubber Formulations

Ingredien

t

Weight (grams)

1 2 3 4 5

SBR 225.

2

198.

4

177.

3

165.

5

155.

3

Stearic

Acid

4.50 3.97 3.55 3.31 3.11

Zinc

Oxide

11.2

6

9.92 8.87 8.28 7.76

6-PPDa 2.25 1.98 1.77 1.66 1.55

CBSb 1.13 0.99 0.89 0.83 0.78

Sulphur 5.63 4.96 4.43 4.14 3.88

Fillerc 0.00 29.7

6

53.1

9

66.2

3

77.6

4

Total 250.

0

250.

0

250.

0

250.

0

250.

0 a N-(1,3-dimethylbutyl)-N'-phenyl-p-phenylene-

diamine) b N-cyclohexyl-2-benzothiazyl sulphenamide c Oil Palm Trunk Fiber Table 2.2: Ingredient weight value based on 250

grams per sample

2.3. Blending

Two rolls mill is used as an equipment to

blend. The SBR were blend in three stages; filler

addition, activator addition and vulcanizing

agent/accelerator addition.

The rubber is blend slowly to make sure the

blending is well homogenous. During rubber

blending, the heater was switched on to enhance

the rubber blending, as SBR became much easier

to form as sheet during heating. The temperature

was set to 80 °C and the speed that being used is

only 12 rotations per minute.

2.4. Molding

The sample were cut into half and pressed in

hot and cold molding press. The temperature of

hot and cold molding press is set at 160 °C for

each plate. The sample were then left for 15

minutes as SBR burn easily to be left under long

period.

2.5. Testing

Tensile test was done in order to check the

improvement of sample from 0 parts until 50

parts oil palm trunk fiber. 50 kN universal tensile

machine was used during the test.

Two chemical used in swelling test;

kerosene and diesel. The samples were cut into 2

pieces each and their weight was taken and

recorded. After that, the samples were put into

two different bottles with kerosene inside one

bottle and diesel inside another bottle. The time

taken to complete the test was 24 hours – exactly

one day. The samples were taken out and dry

then at room temperature before weighing again.

3.0 Result and discussion

3.1. Tensile test

Filler

Content

(PHR)

Time to

break

(Sec)

Highest

Tensile

Strain

(MPa)

Extens

ion

(mm)

0 132.93 0.58 44.31

15 103.00 0.84 34.36

30 67.34 0.77 22.45

40 40.50 0.71 13.52

50 33.55 0.65 10.48

Figure 3.1 below shows the relationship of

time take to break the rubber sample into two

against filler content. Increasing of filler

quantities affect the time to break as the time

show decreasing value, showing that the sample

became more brittle with addition of fillers. This

is because, increasing of filler content into

rubber reduce its plasticity in chain (Hanafi

Ismail et al., 1999). The plasticity of rubber

chain decrease because of the SBR is force to

receive high quantity of filler, despite of their

small quantity in number.

53

Figure 3.1: Graph of time to break (sec) versus

filler content (PHR).

Figure 3.2 below shows that the highest

value tensile strength (MPa) against the filler

content. From 0 parts to 15 parts, the value of

tensile strength increases and decreases after 15

parts onwards. This is show that the best tensile

strength value lays on 15 parts of filler content,

and any filler addition afterward will reduce its

tensile properties.

Figure 3.2: Graph of highest tensile strength

(MPa) versus filler content (PHR).

Z. A. M. Ishak et al., (1994) have reported

that the mechanical properties of rice husk filler

in epoxidized natural rubber (ENR) tensile

strength decreases, with the increasing of filler

content. The best tensile strength will be at 20

PHR filler content, which mean the limit of ENR

exceed after adding filler more than 20 PHR,

resulting in poor tensile strength properties.

Comparing the result in this research with

previous study, the tensile properties of rubber

reinforced with natural filler did increase the

tensile strength at some point, before dropping

again. This is explained why the tensile strength

of styrene butadiene rubber filled with oil palm

trunk fiber increase at 15 PHR of filler content

but decrease afterwards until 50 PHR of filler

content.

Figure 3.3 below show the relationship of

extension of rubber sample before break against

the filler content. The extension became shorter

after adding more filler content. The additions of

filler remove rubber elasticity and increase

brittleness of rubber product.

Figure 3.3: Graph of extension (mm) versus filler

content (PHR).

This is expected as the filling of filler in

rubber matrix causing the plasticity of rubber

chain decrease, increasing the brittleness of

rubber product as well as decreasing their

elasticity. The gap in rubber matrix is filled with

non-elastic filler; reduce its elasticity more with

addition more of filler content.

From previous research, Siti Salina Sarkawi

et al., (2003) have indicated that ground rice

husk in rubber compounding elongation has

increase at 10 PHR rice husk as filler content but

decrease after adding more filler content inside.

This is happened because of blending error; the

filler might not disperse well during blend.

From both results, this research and previous

study, the elongation at break is cause by filler

loading. The more filler is put inside; the rubber

became more brittle and easy to break. This is

due to the tight bonding of rubber compound,

making it more brittle for each addition of filler

contents.

Figure 3.4 show the relationship of tensile

modulus (MPa) against filler content. The value

of young modulus was determined from graph

stress-strain relationship by drawing straight line

and gradient calculate from it.

0

50

100

150

0 20 40 60Tim

e to

Bre

ak

(S

ec)


0

0.2

0.4

0.6

0.8

1

0 20 40 60

Hig

hes

t T

ensi

le

Str

eng

th (

MP

a)


0

10

20

30

40

50

0 20 40 60

Exte

nsi

on

(m

m)


54

Figure 3.4: Graph of young modulus (MPa)

versus filler content (PHR).

The values of tensile modulus increase from

0 parts until 15 parts and drop at 30 parts. The

values then rapidly drop at 40 parts before

increase rapidly at 50 parts. The value of tensile

modulus decrease rapidly must be because of an

error during test. The sample might have crack

earlier than expected after load was applied

causing the value of load decrease rapidly after

that.

From Hanafi Ismail et al., (1999) previous

report, investigation of the mechanical properties

of natural rubber/oil palm wood flour composites

resulting in increasing of tensile modulus with

the increasing of filler loading in rubber

composites. This is because the increasing of

stress over strains which resulting in high tensile

modulus result.

Comparing the result obtained in this

research and previous study, the tensile modulus

is totally different. Perhaps it is cause by

different rubber – which led to different

properties.

3.2. Swelling test

Figure 3.5 show the relationship of chemical

absorption in sample. The graph was plot in two

series; kerosene and diesel.

Figure 3.5: Graph of swelling (%) versus filler

content (PHR).

The maximum absorption of kerosene in

rubber sample is at 50 parts of filler content. This

is because the filler is hydrophilic – ability to

absorb. The more filler content mean the more

hydrophilic area – which is why high quantity of

kerosene can be absorb at high quantity of filler.

The maximum absorption of diesel in rubber

sample is at 30 parts of filler content. The value

seems to vary and high at middle point because

of the error while preparing the sample. Rubber

sample area must be large at 30 parts, causing it

to absorb more diesel than the others.

In overall, rubber sample absorb kerosene

much better than diesel. This is because of low

density of kerosene - 0.78–0.81 g/cm3 compared

to diesel – 0.832 g/cm3.

P.L. Teh et al., (2004) on the other hands

have investigated the organoclay/(carbon

black/silica) addition in epoxidized natural

rubber/natural rubber vulcanized. From the

result, virgin rubber vulcanized has more

tendencies to absorb more chemical than rubber

reinforced filler. The addition of filler increase

chemical resistance property of rubber

compound.

By comparing this research and previous

study, this research provides result with many

errors. The addition of filler should provide more

chemical resistance. This result perhaps comes

from error in blending – the filler is not fully

dispersed.

5.0 Conclusion and recommendation

From the result obtained, time to break,

tensile strength and extension decrease as the

filler content decrease. This is because of the

stiffness and brittleness of rubber sample

-40

-20

0

20

40

60

80

0 20 40 60Ten

sile

Mo

du

lus

(MP

a)


0

50

100

150

200

0 50 100

Sw

elli

ng

(%

)


Kerosene

Diesel

55

increase with increasing of filler content. The

young modulus also increases with increasing of

filler content, as the load over area increase and

the elongation decrease.

The swelling test indicated that kerosene is

being absorbed much better in rubber sample

than diesel. This is because of low density of

kerosene, compared to diesel.

The result obtained from five samples is not

enough to make sure that the properties does

change. Increasing the filler content might give

the better result, and giving more information

about capability of styrene butadiene rubber to

consume more filler.

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mechanical properties of styrene butadiene rubber with oil palm trunk

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