THE EFFECT OF KENAF LOADING AND HYBRIDIZATION OF KENAF WITH EMPTY

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THE EFFECT OF KENAF LOADING AND HYBRIDIZATION OF KENAF WITH EMPTY

FRUIT BUNCH FIBERS OR HALLOYSITE NANOTUBE ON PROPERTIES OF NATURAL

RUBBER LATEX FOAM

SITI NURUL IZZATI BINTI KUDORI

UNIVERSITI SAINS MALAYSIA

2020

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THE EFFECT OF KENAF LOADING AND HYBRIDIZATION OF KENAF WITH EMPTY

FRUIT BUNCH FIBERS OR HALLOYSITE NANOTUBE ON PROPERTIES ON NATURAL

RUBBER LATEX FOAM

by

SITI NURUL IZZATI BINTI KUDORI

Thesis submitted in fulfilment of the requirements for the degree of

Master of Science

January 2020

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ACKNOWLEDGEMENT

First and foremost praise to Allah S.W.T for His love and strength that He given to me to finish my master degree. My sincere appreciation is dedicated to my supervisor, Prof Hanafi Ismail, who in spite of being extraordinary busy with his duty, took time to hear, guide and keep me on the correct path and allowing me to carry out research under his supervision. I cannot imagine how hard it would have been for me to successfully complete my work without his guidance. I also express my gratitude to my co-supervisor, Dr Raa Khimi Shuib, for helping me in writing paper and thesis. Thank you very much for both of you for generous help throughout my research.

I would like to express my thanks to my seniors, and all my fellow friends for their immense help during my research work, writing thesis and for spreading a good vibes to surrounding. My utmost appreciation goes to lab technician to helping me operate the instrument. Not forgetting to thank USM cycling team to make me a part of them and brought me out of my research world in order to enhance my communication skills with the community.

My special thanks go to my beloved parents and family that always being part of my life to encourage me in all my pursuits and inspire me to follow my dreams.

This achievement would not have been possible without your support, both emotional and financial. Thank you so much for believing in me.

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TABLE OF CONTENTS

ACKNOWLEDGEMENT ... ii

TABLE OF CONTENTS ... iii

LIST OF FIGURES ... viii

LIST OF SYMBOLS ... xiii

LIST OF ABBREVIATIONS ... xiv

ABSTRAK ... xvi

ABSTRACT ... xviii

CHAPTER 1 INTRODUCTION ... 1

1.1 Background ... 1

1.2 Problem Statement ... 3

1.3 Research Objectives ... 5

CHAPTER 2 LITERATURE REVIEW... 6

2.1 Polymeric foam ... 6

2.1.1 Classification of polymeric foam ... 8

2.2 Method for synthetic foam ... 8

2.3 Natural Rubber Latex Foam (NRLF) ... 9

2.3.1 Background of Natural Rubber Latex (NRL) ... 9

2.3.2 Introduction of Natural Rubber Latex Foam (NRLF) ... 11

2.3.3 Method for NRLF ... 12

2.3.4 Dunlop method ... 12

2.3.4(a) Preparation of dispersion ... 12

2.3.4(b) Compounding process ... 13

2.3.4(c) Foaming and gelling ... 14

2.4 Fillers ... 14

2.4.1 Natural fiber as a filler ... 16

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2.4.2 Component in natural fiber ... 18

2.5 Kenaf ... 20

2.6 Empty fruit bunch ... 22

2.7 Nanofiller in foam ... 24

2.7.1 Halloysite nanotube... 24

2.8 Factors influencing physical properties of foam ... 26

2.8.1 Structure of foam ... 26

2.8.2 Hybridization of natural fiber filler ... 27

CHAPTER 3 METHODOLOGY... 29

3.1 Introduction ... 29

3.2 Materials ... 30

3.2.1 Kenaf ... 31

3.2.2 Empty fruit bunch ... 31

3.2.3 Preparation of potassium oleate ... 31

3.2.4 Preparation of sodium silicofluoride (SSF) ... 32

3.3 Characterization of natural rubber latex ... 33

3.3.1 Dry rubber content (ASTM 1076-02: Section 9) ... 33

3.3.2 Total solid content (ASTM 1076-02: Section 8) ... 33

3.3.3 Mechanical stability time (ASTM 1076-02: Section 16) ... 33

3.3.4 pH (ASTM D1076-02: Section 15) ... 34

3.4 Equipment ... 34

3.5 Formulation ... 35

3.6 Preparation of kenaf filled NRLF ... 36

3.7 Testing and characterization ... 37

3.7.1 Tensile properties ... 37

3.7.2 Morphology ... 37

3.7.3 Foam density ... 37

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3.7.4 Compressive strength ... 38

3.7.5 Hardness ... 38

3.7.6 Swelling ... 39

3.7.7 Compression set ... 39

3.7.8 Accelerated aging ... 39

CHAPTER 4 RESULTS AND DISCUSSION ... 41

4.1 Introduction ... 41

4.2 Characterization of Natural Rubber Latex ... 42

4.3 Characterization of Kenaf ... 43

4.3.1 Particle size analysis ... 43

4.4 Comparison of kenaf core and bast loading on properties of natural rubber latex foam (NRLF) ... 45

4.4.5 Hardness ... 54

4.4.6 Swelling ... 55

4.5 The effect of different particle sizes of kenaf bast loading on the properties of natural rubber latex foam. ... 60

4.5.5 Hardness ... 67

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4.5.6 Swelling ... 68

4.6 Effect of partially or complete replacement of kenaf by empty fruit bunch (EFB) on the properties of natural rubber latex foam (NRLF) ... 70

4.6.5 Hardness ... 78

4.6.6 Swelling ... 79

4.7 Effect of partially or complete replacement of kenaf by halloysite nanotube (HNT) on the properties of natural rubber latex foam (NRLF) ... 84

4.7.5 Hardness ... 91

4.7.6 Swelling ... 92

CHAPTER 5 CONCLUSION AND FUTURE RECOMMENDATIONS ... 96

5.1 Conclusions ... 96

5.2 Recommendations for Future Work ... 97

REFERENCES ... 98 LIST OF PUBLICATIONS

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LIST OF TABLES

Page

Table ‎2.1 Composition of fresh natural latex ... 9

Table ‎2.2 Types of preserative system used in centrifuged NR latex concentrate ... 11

Table ‎2.3 Typical formulation of natural rubber latex foam ... 13

Table ‎2.4 Classification of fillers based on sources ... 16

Table ‎2.5 Compositions of kenaf fibers ... 22

Table ‎2.6 Chemical composition of EFB ... 23

Table ‎3.1 List of materials... 30

Table ‎3.2 Formulation for potassium oleate ... 32

Table ‎3.3 Formulation of SSF dispersion... 32

Table ‎3.4 List of equipment involved ... 34

Table ‎3.5 Formulation of different loading and sizes of kenaf, partial or complete replacement of NRLF ... 35

Table ‎3.6 Foam and sponge rubber durometer 302 SL value range ... 38

Table ‎4.1 Results of DRC, TSC, MST and pH of the natural rubber latex ... 42

Table ‎4.2 Average length and diameter of kenaf core and bast ... 45

Table ‎4.3 Average cell diameter ... 48

Table ‎4.4 Average cell diameter of various size of kenaf filled NRLF ... 64

Table ‎4.5 Chemical composition of kenaf and EFB ... 72

Table ‎4.6 Average cell diameter of kenaf/EFB filled NRLF ... 75

Table ‎4.7 Average cell diameter of kenaf/HNT filled NRLF ... 89

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LIST OF FIGURES

Page

Figure 2‎.1 Structure of the foam: a) open cell, b) closed cell... 7

Figure 2‎.2 Microstructure of foam ... 7

Figure 2‎.3 Separation of fresh latex on ultracentrifugation ... 10

Figure 2‎.4 Functions of filler in polymers ... 15

Figure 2‎.5 Classification of natural fibers ... 17

Figure 2‎.6 Microstructure of natural fiber ... 19

Figure 2‎.7 Chemical structure of (a) cellulose (b) hemicellulose (c) lignin ... 20

Figure 2‎.8 Cross section of kenaf stalk ... 22

Figure 2‎.9 Empty fruit bunch waste ... 23

Figure 2‎.10 Structure of Halloysite Nanotube (HNT) ... 25

Figure 2‎.11 EFB fibers ... 28

Figure 3‎.1 Flow chart of the entire research work ... 30

Figure 4‎.1 Particle size distribution of kenaf ... 43

Figure 4‎.2 Micrograph of kenaf core (a) magnification at 35x (b) magnification at 100x ... 44

Figure 4‎.3 Micrograph of kenaf bast (a) magnification at 35x (b) magnification at 100x ... 45

Figure 4‎.4 Micrograph of NRLF surface at magnification of 50x; (a)control NRLF, (b) 1phr of kenaf core filled NRLF, (c) 1 phr kenaf bast filled NRLF, (d) 7 phr kenaf core filled NRLF, (e)7 phr kenaf bast filled NRLF ... 47

Figure 4‎.5 The effect of filler loading on tensile strength of kenaf core or bast filled NRLF ... 49

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Figure 4‎.6 The effect of filler loading on elongation at break of kenaf core or bast filled NRLF ... 50 Figure 4‎.7 The effect of filler loading on modulus 100% elongation (M100) of

kenaf core or bast filled NRLF ... 51 Figure 4‎.8 The effect of filler loading on density of kenaf core or bast filled

NRLF ... 52 Figure 4‎.9 The effect of filler loading on compression strength at 50% strain

of kenaf core or bast filled NRLF ... 53 Figure 4‎.10 The effect of filler loading on compression modulus at 50% strain

of kenaf core or bast filled NRLF ... 53 Figure 4‎.11 The effect of filler loading on hardness of kenaf core or bast filled

NRLF ... 55 Figure 4‎.12 The swelling percentage of kenaf core or bast filled NRLF ... 56 Figure 4‎.13 Constant deflection compression set, Ct of kenaf core or bast

filled NRLF ... 57 Figure 4‎.14 Recovery percentage of kenaf core or bast filled NRLF ... 57 Figure 4‎.15 Effect of filler loading on tensile strength of kenaf core or bast

filled NRLF after the aging process ... 59 Figure 4‎.16 Effect of filler loading on elongation at break of kenaf core or

bast filled NRLF after the aging process ... 59 Figure 4‏.17 Effect of filler loading on M100 of kenaf core or bast filled NRLF

after the aging process ... 60 Figure 4‎.18 The effect on tensile strength of various sized kenaf filled NRLF .... 61 Figure 4‎.19 The effect on elongation at break of various sized kenaf filled

NRLF ... 62 Figure 4‎.20 The effect on modulus at elongation (M100) of various sized kenaf

filled NRLF ... 63 Figure 4‎.21 Surface micrograph at magnification 150 x (a) control NRLF (b)

3 phr of 97 µm (c) 3 phr of 144 µm (d) 3 phr of 200 µm ... 64

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Figure 4‎.22 The effect on foam density of various sized kenaf filled NRLF ... 65 Figure 4‎.23 The effect on compression strength 50% strain of various sized

of kenaf filled NRLF ... 66 Figure 4‎.24 The effect on compressive modulus 50% strain of various sized

of kenaf filled NRLF ... 66 Figure 4‎.25 The effect on hardness of various sized of kenaf filled NRLF ... 67 Figure 4‎.26 The effect on swelling percentage of various sized of kenaf filled

NRLF ... 68 Figure 4‎.27 The effect on constant deflection of compression set of various

sized of kenaf filled NRLF ... 69 Figure 4‎.28 The effect on percentage of recovery of various sized of kenaf

filled NRLF ... 70 Figure 4‎.29 The tensile strength of partial or complete replacement of kenaf

by EFB filled NRLF ... 71 Figure 4‎.30 The elongation at break of partial or complete replacement of

kenaf by EFB in NRLF ... 72 Figure 4‎.31 The modulus at 100% (M100) of partial or complete replacement

by EFB of kenaf filled NRL ... 73 Figure 4‎.32 Surface micrograph (a) EFB magnification at 100 x, (b) 7/0 of

kenaf/ EFB, (c) 3.5/3.5 of kenaf/EFB and (d) 0/7 of kenaf/EFB ... 75 Figure 4‎.33 Foam density of partial or fully replacement of kenaf by EFB

filled NRLF ... 76 Figure 4‎.34 Compression test of partial or fully replacement of kenaf by EFB

filled NRLF at 50% strain ... 78 Figure 4‎.35 Compression modulus of partial or fully replacement of kenaf by

EFB filled NRLF at 50% strain ... 78 Figure 4‎.36 Hardness of partial or fully replacement of kenaf by EFB filled

NRLF ... 79

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Figure 4‎.37 Swelling percentage of partial or fully replacement of kenaf by EFB filled NRLF ... 80 Figure 4‎.38 Compression set of partial or fully replacement kenaf by EFB

filled NRLF ... 81 Figure 4‎.39 Recovery percentage of partial or fully replacement of kenaf by

EFB filled NRLF ... 81 Figure 4‎.40 Tensile strength of partial or fully replacement kenaf by EFB

filled NRLF after the aging process ... 83 Figure 4‎.41 Elongation at break of partial or fully replacement kenaf by EFB

filled NRLF after the aging process ... 83 Figure 4‎.42 Modulus at 100% (M100) of partial or fully replacement kenaf by

EFB filled NRLF after the aging process ... 84 Figure 4‎.43 Tensile strength of partial or fully replacement kenaf by HNT

filled NRLF ... 85 Figure 4‎.44 Elongation at break of partial or fully replacement kenaf by HNT

filled NRLF ... 86 Figure 4‎.45 Modulus at 100% of partial or fully replacement kenaf by HNT

filled NRLF ... 86 Figure 4‎.46 Surface micrograph of kenaf/HNT filled NRLF with (a) 0/7 phr

of kenaf/HNT, (b 3.5/3.5 phr of kenaf and (c) 0/7 phr kenaf/HNT .. 88 Figure 4‎.47 Foam density of partial or fully replacement of kenaf by HNT

filled NRLF ... 90 Figure 4‎.48 Compressive strength of partial or fully replacement of kenaf by

HNT filled NRLF at 50% ... 91 Figure 4‎.49 Hardness of partial or fully replacement of kenaf by HNT filled

NRLF ... 92 Figure 4‎.50 Swelling percentage of partial or fully replacement of kenaf by

HNT filled NRLF ... 93 Figure 4‎.51 Compression set of partial or fully replacement of kenaf by HNT

filled NRLF ... 94

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Figure 4‎.52 Recovery percentage of partial or fully replacement of kenaf by HNT filled NRLF ... 94 Figure 4‎.53 Tensile strength of partial or fully replacement of kenaf by HNT

filled NRLF after aging ... 95 Figure 4‎.54 Elongation at break of partial or fully replacement of kenaf by

HNT after aging ... 95

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LIST OF SYMBOLS

°C Degree celcius

µm Micron meter

g Gram

g/cm³ Gram per cubic centimeter

mm Milimeter

mm/min Millimeter per minute

Mm² Cubic milimeter

MPa Megapascal

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LIST OF ABBREVIATIONS

CFC Chlorofluorohydrocarbons

CO Carbon monoxide

CO₂ Carbon dioxide

DPG Diphenylguanidine

DRC Dry rubber content

Eb Elongation at break

EFB Empty fruit bunch

EPDM Ethylene propylene diene monomer

HCN Hydrogen cyanide

HDPE High density polyethylene

HFC Hydrofluorocarbon

HNT Halloysite nanotube

NRLF Natural Rubber Latex Foam M₁₀₀ Modulus at 100% elongation

PC Polycarbonate

PE Polyethylene

PP Polypropylene

PS Polystyrene

PU Polyurethane

PVC Polyvinyl chloride

SEM Scanning electron microscopy SSF Sodium silicofluoride

TSC Total solid content

UV Ultraviolet

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xv ZDEC Zinc diethyldithiocarbamate ZMBT Zinc 2-mercaptobenzothiolate

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KESAN PEMBEBANAN KENAF DAN PENGHIBRIDAN KENAF DENGAN GENTIAN TANDAN KOSONG KELAPA SAWIT ATAU TIUB NANO HALOISIT KE ATAS SIFAT-SIFAT BUSA LATEKS GETAH ASLI

ABSTRAK

Penyebatian kenaf di dalam busa lateks getah asli (NRLF) telah disediakan melalui kaedah Dunlop. Morfologi, sifat-sifat tegangan, ketumpatan busa, pemampatan kekerasan dan penuaan terma NRLF terisi kenaf telah dianalsis dalam kajian ini. Kandungan kenaf ‘core’ dan ‘bast’ yang berbeza (0,1,3,5,7 phr) telah dikaji. Kekuatan tegangan, pemanjangan pada takat putus (Eb) dan kekuatan mampatan NRLF terisi ‘core’ atau ‘bast’ berkurang dengan peningkatan pembebanan kenaf. Walaubagaimanapun, modulus pada pemanjangan 100% (M100), kekerasan dan ketumpatan NRLF telah meningkat dengan peningkatan pembebanan kenaf.

Penambahan kenaf ‘core’ ke dalam NRLF telah meningkatkan peratusan pembengkakan dan peratusan retensi penuaan berbanding kenaf ‘bast’. Keputusan pengimbasan mikroskop electron (SEM) menunjukkan yang kenaf ‘bast’ bergentian mempunyai lekatan kuat berbanding kenaf ‘core’ zarahan menghasilkan kekuatan tegangan, Eb dan kekuatan mampatan yang lebih tinggi. Kesan perbezaan saiz kenaf

‘bast’ (97, 144, 200 µm) terisi NRLF juga telah dikaji. Keputusan menunjukkan saiz kenaf yang lebih kecil didalam NRLF meningkatkan kekuatan tegangan, kekuatan mampatan, set mampatan dan kekerasan pada kandungan kenaf yang sama. Saiz tetingkap sel meningkat apabila saiz pengisi meningkat. Penghibridan kenaf/tandan kosong kelapa sawit (EFB) telah menunjukkan bahawa saiz tetingkap sel menjadi lebih besar dengan peningkatan kandungan EFB menyebabkan pengurangan di dalam sifat-sifat mekanik. Untuk penuaan terma, NRLF terisi EFB mempunyai

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peratusan retensi kekuatan regangan dan M₁₀₀ lebih tinggi berbanding NRLF terisi kenaf. Penggantian tiub nano haloisit untuk NRLF terisi kenaf menggalakkan tetingkap sel untuk bergabung antara satu sama lain dan meningkatkan lagi pembentukan tetingkap sel yang lebih besar.

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THE EFFECT OF KENAF LOADING AND HYBRIDIZATION OF KENAF WITH EMPTY FRUIT BUNCH FIBERS OR HALLOYSITE NANOTUBE ON PROPERTIES OF NATURAL RUBBER LATEX FOAM

ABSTRACT

Natural rubber latex foam (NRLF) become great interest to the society due to its function in various applications. However, the usage of natural filler in NRLF from previous literature are do not perform very well. The aim of this research was to produce NRLF with different component of kenaf and hybridization of kenaf with Empty Fruit bunch (EFB) and Halloysite Nanotube (HNT) in order to provide good mechanical and physical properties. The incorporation of kenaf in natural rubber latex foam (NRLF) was prepared by using Dunlop method. Morphology, tensile properties, density, compression, hardness and thermal aging of kenaf filled NRLF were analysed in this work. The different loading of kenaf core or bast (0,1,3,5,7 phr) was studied. The tensile strength, elongation at break (Eb) and compressive strength of kenaf core or bast filled NRLF samples decreased as the loading of kenaf was increased. However, the modulus at 100% elongation (M100), hardness and density of NRLF increased with increasing kenaf loadings. The addition of kenaf core into NRLF increased the swelling percentage and retention percentage of aging compared to the kenaf bast. Scanning electron microscope (SEM) results indicated that the fibrous kenaf bast had strong adhesion compared to the particulate kenaf core, resulting higher tensile strength, Eb and compression strength. The effect of different size of kenaf bast (97, 144, 200 µm) filled NRLF was also studied. It revealed that the smaller size of kenaf filled NRLF showed higher in tensile properties, compression strength, compression set and hardness at the same kenaf loading. The

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size of the window cell increases as size of the filler increased. The hybridization of kenaf/ EFB showed that the size of cell window become larger with increasing EFB loading resulting in reduction of mechanical properties. For thermal aging, EFB filled NRLF has higher retention percentage of tensile strength and M100 compared to kenaf filled NRLF. The substitution of halloysite nanotube in kenaf filled NRLF promotes the cell window to coalesce each other and increase the formation of larger cell window.

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1 CHAPTER 1

INTRODUCTION

1.1 Background

Foam is a porous structure that made by trapping a solid and gas phase (Sivertsen, 2007). Over the past few decades, foam has attracted increasing attention and has been considered for applications such as automotive parts, acoustic absorbent, and sporting equipment (Mohebbi et al., 2015). Foam has its own advantages as compared to the other types of materials which is lightweight product and low cost. Foam can comes from different types of materials like metal, polymer and ceramic. In addition, 10% of the foam production comes from the polymer materials. (Ariff et al., 2008).

Generally, polymeric foam is made up from the combination of gaseous in the solid polymer matrix. Polymeric foam can be either in thermoplastic, thermoset, cellular elastomers or expanded rubber. Polymer foam was taking place in the industry in early 1914 as sponge rubber (Frisch, 1981). The polymeric foam has brought some development in foam technology. Enormous amount of polymeric foam product are being used in our daily life like disposal packaging, cushioning and furniture. Polymeric foam can be classified into two kinds; closed cell and open cell.

Closed cell foam has an enclosed wall and the cells do not interconnecting between one another and it is more rigid. It usually used for noise or thermal insulation, lightweight structure purpose and sealing (Dalongeville et al., 2017). While, for the open cell foam, the cells are broken and thus allowing the air to fill the spaces within.

It also gives a unique characteristic to the foam which it can return to its original state after forces are being applied.

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Thermoplastic foam is the biggest contributor to the polymer foam production. Thermoplastic is made from petroleum-based, and being categories as non-renewable product. Various types of thermoplastic are commonly used in the foam production like polystyrene (PS), polyurethane (PU), polypropylene (PP), polyvinyl chloride (PVC) and polycarbonate (PC) (Gama et al., 2018). The production of polyurethane foam is higher as compared to the other types of foam. It was approximately 11.5 million tonnes of polyurethane production in 2014 and it estimated to be over 15.5 million tonnes in 2019 (Agrawal et al., 2017).

Unfortunately, the growth of the thermoplastic foam brings a greater attention in the environmental sustainability as the world now is facing depletion of the petroleum oil at an alarming rate (Bergeret and Benezet, 2011).

Today, in the growth of environmental awareness, development of green and natural products has become an interesting research topic. Natural rubber latex foam (NRLF) is one of the products that comes from the natural rubber. It can be obtained when a stable dispersion of natural rubber latex (NRL) and chemicals are being converted into a porous solid material. The production of moulded latex foam was founded by the Dunlop Rubber company in 1930 (Lim and Amir-Hashim, 2011). In the 1950s, after recovery from the World War II, 70% of global productions of rubber latex were used to make latex foam. The combination of natural fibers in polymer promotes the development of engineering green materials as it comes from natural or renewable resources.

In early 2010, kenaf was planted in large scale in Malaysia as an alternative crop to replace the tobacco plantation due to reduction in the tobacco price and its import duty (Basri et al., 2014). Kenaf (Hibiscus cannabinus) is a tropical plant of

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Malvaceae family that yields a fiber resembling jute that can be used for the production of textile and cordage. Every parts of kenaf become crucial in their respective as it is a renewable materials and environmental friendly.

1.2 Problem Statement

These days, commercial foam originated from the oil based item like polyurethane (PU) foam, polyethylene (PE) foam, and polycarbonate (PC) foam. Oil is a inexhaustible asset that we have to moderate as it faces a genuine exhaustion issue. The usage of NRLF act as a promising green foam as it comes from the rubber trees which are renewable resources. The NRLF is indeed an excellent choice for having high level comfort capability and extra durability as compared to the synthetic or blended latex. The NRLF has been used in the bedding and furniture industries for manufacturing mattresses, pillows and automobile products like car seats, cushions and insulation materials (Lim and Amir-Hashim, 2011). Recently, many researchers have been carried out to study the properties of NRLF by using various kinds of fillers. The usage of natural fibers as a filler in NRLF was extensively explored due to their sustainability and renewability characteristics..

Ramasamy et al. (2013) studied the aqeous dispersion of rice husk powder in NRLF.

The physical properties of NRLF with different type of filler like rice bran, longan shell and organic fertilizer has been explored by Pornprasit and Aiemrum, (2018).

Abdul Karim et al. (2016) reported on the kenaf filled NRLF, however the different loading of kenaf effects on the properties of NRLF. The NRLF with higher loading of kenaf do not perform very well. The previous works have not comprehensively considered the different component of kenaf to be incorporated with NRLF. The

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incorporation of different components of kenaf in NRLF is another approach for selecting the best properties of different components of kenaf in NRLF.

In this study, different loading of kenaf core or bast was used as a filler in NRLF. This is considered as the fundamental parameter to assess the best component and loading of kenaf filled NRLF. There are several factors that effect on the properties of NRLF like structure, dimension, shape and chemical composition.

Moreover, one of the important parameters that affecting the properties of NRLF is the size of the fillers. The particle size has great influence on the reinforcement ability of the fillers (Nourbakhsh and Karegarfard, 2010). However, kenaf had some unfavourable effect on the adhesion and compatibility with the NRLF. This was due to the nature kenaf, which is hydrophilic, as they are derived from lignocellulose.

Therefore, employing combinations of different type of filler is one of the approach in order to improve the properties of final product.

The hybridization of kenaf and empty fruit bunch (EFB) from the oil palm waste are being used as filler in the production of NRLF in order to promote green foam product with a great polymeric sponge material for various application like sound absorbance, oil absorbance, upholstery product, pillow and mattress. The EFB waste generated from the industry is estimated to be about 8x10⁶tons per year (Rozman et al., 2000) The usage of natural fibers from empty fruit bunches could help the oil palm industry in Malaysia to reduce the by-product waste of palm oil (Suzana and Ahmad, 2012). Furthermore, the possibility of utilizing high loading of EFB with kenaf in NRLF will reduce the cost of final product.

Nanofiller has drawn many attentions and be considered as high potential filler materials for improving mechanical and physical properties of polymer matrix.

The combination of nanofiller with natural filler will reduce the water absorption