Journal of the Rubber Research Institute of Sri Lanka (2015) 95, 1-13

Effect of coated fibre on cure characteristics and physico-mechanical properties of -coir composites

D G Edirisinghe*, W D M Sampath* and P C Wettasinghe*

*Rubber Research Institute of Sri Lanka, Telewala Road, Ratmalana, Sri Lanka ______

Abstract A wide variety of natural fibres such as coconut fibre (coir), bagasse, fibre, sisal, etc. can be used to reinforce . Natural fibre reinforced, biodegradable composites are eco-friendly. However, the interfacial adhesion between natural fibre and most of the biodegradable polymers is not adequate. The objective of this study was to modify readily available coir by coating with natural rubber (NR) as well as synthetic rubber latices with the aim of improving adhesion between coir and rubber in order to develop a coir filled NR based composite suitable in manufacture of tyre treads. Coir was coated with different compounded latices namely, neoprene, nitrile and NR and with uncompounded NR latex. Thereafter, composites were produced by mixing 15 phr of the latex coated coir fibres with virgin NR according to a tyre tread formulation and properties of the composites were evaluated and compared. Results revealed that processing safety of the compounded NR latex coated coir filled rubber composite is higher than that of the other three composites, whereas uncompounded NR latex coated coir filled rubber composite showed a similar processing safety to that of the two synthetic latex coated coir filled rubber composites. However, the two NR latex coated coir filled rubber composites were faster curing than the synthetic latex coated coir filled rubber composites. Minimum torque results indicated that compounded NR latex coated coir filled rubber composite has a higher processability when compared to the other composites. However, the latter composites indicated a higher state of cure and cross-link density in comparison to the former composite. Tensile strength, elongation at break, resilience and abrasion volume loss of the compounded NR latex coated coir filled rubber vulcanisate are superior to those of the other three vulcanisates. In overall cure characteristics and mechanical properties, especially abrasion resistance of the composite based on compounded NR latex coated coir indicates that it could be used in manufacture of tyre treads.

Keywords: coir, natural rubber composites, natural rubber latex, neoprene latex, nitrile latex

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Natural rubber composites with surface treated coir

Introduction Coir is a versatile lignocellulose fibre Natural fibres are generally obtained from the coconut (Cocos lignocellulosic in , consisting of nucifera), which grows extensively in helically wound cellulose microfibrils in tropical countries. Because of its hard- a matrix of lignin and hemicellulose. wearing quality, durability and other Natural fibres have been used to advantages, it is used for making a wide reinforce materials for over 3,000 years. variety of floor furnishing materials, More recently they have been employed yarn and rope. However, these in combination with rubber and plastics traditional coir products consume only a (Sakdapipanich et al., 2007). Many small percentage of the potential total types of natural fibers have been world production of coconut husk. In investigated for use in rubber and the past, composites of coconut plastic including coconut fibre (coir), fibre/natural rubber (NR) latex were fibre, oil palm fibre, isora fibre, extensively used by the automotive banana fibre, sisal, etc. Natural fibres industry (Geethamma et al, 1998) and have the advantage that they are presently mattresses, pots, etc. are renewable resources and have widely produced using this marketing appeal. They are increasingly combination. Apart from the used in automotive and packaging conventional uses of coir as mentioned materials. above, research and development work Natural fibres degrade faster than has been conducted to find new synthetic fibres in natural environments, applications for coir, including minimizing environmental pollution. utilization of coir as a reinforcing However, biodegradation of natural material for plastics (Owolabi et al., fibre can decrease the life time of fibre 1985). reinforced composites. To Coir is an inexpensive fibre among the prolong their performance in natural various natural fibres available in the environments, natural fibres are treated world. Furthermore, it possesses the to protect from any circumferential advantages of a lignocellulose fibre. It is agents. Hydroxyl groups from cellulose not toxic and possesses no waste and lignin are natural substrates for disposal problem. Unfortunately, the modification. In addition, coating of performance of coir as a reinforcement fibres often reduces water absorption, in polymer composites is unsatisfactory protection from bacteria and fungi and not comparable even with other attack. The treatment methods which natural fibres. This inferior performance have been used for fibre reinforced of coir is due to various factors such as polymer composites are not suitable for its low cellulose content, high lignin and protection of the fibres in contact with hemicellulose content, high soils (Farshid et al., 2011). microfibrillar angle and large and

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D G Edirisinghe et al. variable diameter (Geethamma et al., al., 1993). Prasad et al. (1983) reported 1998). that the use of alkali treatment on coir The hydrophobic NR matrix and fibres improves the mechanical hydrophilic cellulose fibre can be made properties of coir-polyester composites. compatible through modification of Jacob et al. investigated the effect of polymer or fibre surface. The extent of chemical modification of banana fibre adhesion is usually increased by the use in NR (Communicated). Modification of of bonding agents and chemical banana fibre resulted in superior modification of fibres. The effects of a mechanical properties. Chemical silane coupling agent (Si69) on curing modification of both sisal and oil palm characteristics and mechanical fibres was imperative for increased properties of bamboo fibre filled NR interfacial adhesion and resulted in composites were studied (Ismail et al., enhanced properties (Jacob et al., 2004). 2002). The mechanical properties of The influence of alkali treatment on oil composites such as hardness, modulus, palm fiber reinforced NR composites tensile and tear strengths improved with was investigated by Joseph et al. the addition of Si69. Chemical (2006). They observed superior treatment of cellulose fibres usually mechanical properties for the changes the physical and chemical composites after chemical modification structure of the surface. The use of due to better adhesion. Effects of alkali, maleic anhydride grafted copolymer and silane coupling agent and acetylation on alkaline treatment of the natural fibre oil palm fibres have been studied by are the most used techniques with the Mahato et al. (1993). De et al. (2006) aim to improve the fibre-matrix were able to improve adhesion between interfacial bonding (Ku et al., 2011). grass fiber and NR matrix by alkali Arumugam et al. (1989) evaluated treatment. mechanical properties of NR Chemical modification of pineapple composites prepared with pristine and fiber in NR was investigated by sodium hydroxide treated coconut Lopattananon et al. (2006). Sodium fibers. They added the same coupling hydroxide and benzoyl peroxide were agents as Ismail et al. (2001) in order to used to treat the surfaces of fiber. It was improve rubber-filler interactions. found that all surface modifications Results of the compounds prepared with enhanced adhesion and tensile pristine and treated fibres were properties. The effects of different compared with those of untreated fibres chemical treatments, including and an enhancement in the mechanical mercerisation, acetylation, benzoylation properties was observed. It was reported and treatment with toluene diisocyanate that alkali treatment on coir fibre (TDI) and silane coupling agents, on enhances the thermal stability and isora fibre properties and mechanical maximum moisture retention (Mahato et properties were analyzed. Isora fibre 3

Natural rubber composites with surface treated coir was seen to have immense potential as Experimental reinforcement in NR. Acetylation and Materials TDI treatments gave higher tensile Neoprene and nitrile latex compounds strength values compared to other were supplied by Dipped products Plc., treatments (Mathew et al., 2004). Maize Sri Lanka. Compounded NR latex, stalk fibres were also chemically treated uncompounded NR latex and virgin NR with acetic anhydride (acetylation) to (RSS 2) were purchased from a local enhance their compatibility with the supplier. Zinc oxide (ZnO), stearic acid, hydrophobic rubber matrix (Chigondo carbon black (N 330-high abrasion et al., 2013). The NR-maize stalk fibre furnace black), rubber processing oil filled composites showed good (Dutrex ), IPPD (N-isopropyl, N’- processing safety and when compared phenyl paraphenylene diamine), TMQ with untreated NR-maize stalk fibre (2,2,4 trimethyl 1,2-dihydroquinoline), composites, the acetylated composites TBBS (N-t-butyl-2 benzothiazole exhibited higher mechanical properties, sulphenamide) and sulphur were reduced moisture absorption and higher purchased from the local market. resistance to hydrothermal aging. Coconut fibre (coir) was supplied by a The effect of plasma treatment on local supplier and was used as received. cellulose fibers in NR composites was investigated by Ahlblad et al. (1994). Method Chemiluminescence analysis was used Coconut fibre was coated with to indicate the grafting on the surface of compounded neoprene latex, the cellulose fibres and also to estimate compounded nitrile latex, compounded the effect of the plasma on the cellulose NR latex and uncompounded NR latex. fibres. The results indicated the Neoprene and nitrile latices were chosen possibility of obtaining a surface layer as coating materials for coir as these are on the fibres, which would lead to readily available and existence of some improvement of mechanical properties similarities between each of the of rubber composites. structures of the two synthetic rubbers The use of chemical treated natural and the structure of NR. Further, better fibres such as coir in composites has adhesion between each of the two polar increased due to their benefits such as synthetic rubber latices and coir would high strength with very low weight and be expected due to the presence of recyclable nature. However, no work on hydroxyl groups in cellulose and lignin latex coating of natural fibres has been of coir. Four composites were produced reported in the past. Hence, this by mixing the latex coated fibres with research was conducted to study the virgin NR according to the formulations effect of latex coating of coir on given in Table 1. properties of NR-coir composites.

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Table 1. Formulations of latex coated coir filled rubber composites

Ingredient Formulation S1 S2 S3 S4 Natural rubber (RSS 2) 100 100 100 100 Zinc oxide 5.0 5.0 5.0 5.0 Stearic acid 1.5 1.5 1.5 1.5 Processing oil 3.0 3.0 3.0 3.0 Sulphur 2.5 2.5 2.5 2.5 Flectol H 1.0 1.0 1.0 1.0 MBT 1.5 1.5 1.5 1.5 Uncompounded NR latex coated coir 15 00 00 00 Compounded neoprene latex coated coir 00 15 00 00 Compounded nitrile latex coated coir 00 00 15 00 Compounded NR latex coated coir 00 00 00 15

Properties of the composites containing The first stage of mixing was carried out compounded latex coated fibres were using a Baker Perkins Engineers, evaluated and compared with those of Petersborough and London, laboratory the composite containing Banbury and the second stage was uncompounded NR latex coated fibres. carried out using a David Bridge & Co. The mixing cycle used in the Ltd. Castleton Rochdale, England, preparation of latex coated coir filled laboratory two-roll mill (6” x 13”). rubber composites is given in Table 2.

Table 2. Mixing cycle used in the preparation of latex coated coir filled rubber composites

Stage 1: Internal mixer Total time (min.) Added NR (RSS 2) 0 Added ZnO + Stearic acid + Flectol H 2 Added ½ (latex coated coir + oil) 4 Added remaining ½ (latex coated coir + oil) 6 Dumped 7 Stage 2: Two-roll mill Added MBT 8 Added sulphur 9 Sheeted out 10

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Natural rubber composites with surface treated coir

Determination of cure characteristics IRHD N-scale as per ISO 48:2010. of the latex coated coir filled rubber Resilience of the vulcanisates was composites measured by a Wallace Lupke Cure characteristics such as the pendulum in accordance with ISO 4662: minimum torque (ML), maximum torque 2009. Abrasion volume loss of the (MH), scorch time (TS2), optimum cure vulcanisates was determined using a time (T90), cure rate (CRI) and DIN abrasion tester in accordance with delta cure (MH-ML) of the four rubber DIN 53516. compounds were obtained by a MDR 2000 Moving Die Rheometer (M/S Determination of aging properties of Alpha Technologies, USA) at 150oC. the vulcanisates Tensile and tear strengths were Preparation of latex coated coir filled evaluated after aging. Aging was carried rubber vulcanisates out in an air circulating oven at 100oC The four latex coated coir filled rubber (Sanyo Gallenkamp, UK) for 22 h composites were placed in test piece according to ISO 188: 2011. moulds and pressed between the platens of a hydraulic press (Yeji Corporation, Results and Discussion Taiwan). The samples were cured at Cure characteristics of the latex coated 150oC temperature and at an applied coir filled rubber composites pressure of 20 MPa according to Cure characteristics of the four rubber respective optimum cure times obtained composites are given in Table 3. from the rheographs. After curing, the Minimum torque (ML) is an indication test pieces were removed from the of the processability and is related to the moulds and immediately cooled under stock viscosity of the compound. The tap water to prevent further curing. minimum torque of compounded NR latex coated coir filled rubber composite Measurement of physico-mechanical (S4) is lower and hence the properties of the latex coated coir processability is higher than that of the filled rubber vulcanisates other composites (Table 3) and it may A GotechTesting Machines Inc. tensile be due to better distribution of the testing machine was used to measure compounded NR latex coated coir in the the tensile properties of the rubber NR matrix. Maximum torque (MH) vulcanisates in accordance with ISO 37: indicates the state of cure and delta cure o 2011 at room temperature (27±2 C) at a (MH-ML) is an indication of the cross- grip separation rate of 500 mm/min. link density. MH and delta cure of Tear strength of the vulcanisates was compounded NR latex coated coir filled measured using angle (Die B) test composite is lower than those of the pieces with the aid of the same machine others. Neoprene latex coated coir filled as per ISO 34-1:2010. Hardness of the composite (S2) has the highest crosslink vulcanisates was measured by a “Digi density compared to S1 and S4 Test” hardness tester for hardness in the composites (Table 3).

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Table 3. Cure characteristics of the latex coated coir filled rubber composites

Sample Minimum Maximum Delta cure Scorch Cure Cure rate No torque (ML) torque (MH) (MH-ML) time (ts2) time (t90) index dNm dNm (dNm) min. min. min-1 S1 2.25 9.34 7.09 0.31 2.27 51 S2 2.39 12.90 10.51 0.29 3.32 33 S3 2.42 11.48 9.06 0.31 3.11 36 S4 1.62 7.66 6.04 1.13 2.34 83

S4 composite containing compounded Physico-mechanical properties of NR latex coated coir has the highest latex coated coir filled rubber scorch time (ts2) or in other words the vulcanisates highest processing safety. However, Hardness variation of the four rubber there is no significant difference composites is shown in Figure 1. This between the scorch time of the figure shows that there is no significant composites S1, S2 and S3. Table 3 difference between the hardness of S2 indicates that composites S1 and S4 and S3 vulcanisates and they are containing NR latex coated coir are markedly higher than that of the S1 and faster curing than the other two S4 vulcanisates. When synthetic latices composites. In S1 and S4 composites, are coated on coir it becomes stiff due there are more crosslinking positions to reduced elasticity and this is probably due to the presence of a greater number the cause for higher hardness shown by of double bonds and this is probably the the S2 and S3 vulcanisates compared to reason for faster cure of the composites. S1 and S4 vulcanisates.

70 60

50 40 30

20 Hardness (IRHD) Hardness 10 0

S1 S2 S3 S4

Modification technique

Fig. 1. Variation of hardness of latex coated coir filled rubber vulcanisates

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Natural rubber composites with surface treated coir

Similar to hardness, modulus at 300% homogeneous fibre dispersion in order elongation of synthetic latex coated coir to achieve maximum strength and filled vulcanisates is markedly higher performance of the composite materials than that of the NR latex coated coir (Visakh et al., 2012). filled vulcanisates (Fig. 2). There is no significant difference As expected, tensile strength of the NR between the elongation at break of S1 latex coated coir filled vulcanisates is and S4 vulcanisates (Fig. 4). The lower greater than that of the synthetic latices hardness shown by the S1 and S4 coated coir filled vulcanisates (Fig. 3). vulcanisates reflects higher elongation This indicates good adhesion between at break for the same compared to S2 virgin NR and NR latex coated coir. In and S3 vulcanisates. However, other words, NR latex coating has elongation at break of all the four improved adhesion between NR and vulcanisates is at a level acceptable for coir. Jacob & Anandjiwala (2009) tyre treads. Generally, higher reported that when fibres are aligned homogeneity or compatibility indicates parallel to the stress direction, tensile higher elongation at break. Since S1 and strength develops a characteristic drop S4 vulcanisates are more homogeneous, with increasing fibre volume content higher elongation at break has resulted until a critical fibre level is reached. for the same. Further, it is important to ensure

3.5

3 2.5

2

1.5 1

0.5 Modulus at 300% (MPa) at 300% Modulus 0 S1 S2 S3 S4 Modification technique

Fig. 2. Variation of modulus at 300% elongation of latex coated coir filled rubber vulcanisates

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14

12

10 8 6 4

2 (MPa) strength Tensile 0 S1 S2 S3 S4 Modification technique

Fig. 3. Variation of tensile strength of latex coated coir filled rubber vulcanisates

800 700 600

500

400 300 200

(%) break at Elongation 100 0 S1 S2 S3 S4

Modification technique

Fig. 4. Variation of elongation at break of latex coated coir filled rubber vulcanisates

Tear strength of the vulcanisate S1 is shear strength in polymer matrix higher than that of the other (Yousif & Tayeb, 2007). With NR latex vulcanisates (Fig. 5). This indicates that coated coir, fiber is exposed more to the S1 is the most homogeneous polymer matrix, leading to proper vulcanisate. The initiated crack would interaction between the surfaces (Khalid tend to propagate through the interface et al., 2008). Additionally, since S1 and the extent of propagation depends contains coir coated with on interfacial adhesion between the uncompounded NR latex, crosslinks latex coated coir and NR matrix. NR would be evenly distributed between the latex coated coir improves its interfacial latex coating and NR matrix unlike in

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Natural rubber composites with surface treated coir the case of composite S4. Hence an measure of the amount of energy that is interface would not exist between coir absorbed. The highest resilience is and the matrix. This results in higher shown by the S4 vulcanisate and is in tear strength for the S1 composite. agreement with the results of elongation The ratio of energy returned to the at break. The resilience of nitrile latex energy applied is termed as the coated coir filled vulcanisate (S3) is resilience (Fig. 6). When the very much lower than that of the other deformation is an indentation due to three vulcanisates. The lower elasticity single impact, this ratio is termed of the S3 vulcanisate could be attributed “rebound resilience”. If the elasticity is to lower elongation at break of the higher, then less deformation energy is same. dissipated as heat. Heat build-up is a

50 40

30

20 10

0 Tear strength (KN/m) strength Tear S1 S2 S3 S4 Modification technique

Fig. 5. Variation of tear strength of latex coated coir filled rubber vulcanisates

90 80 70 60

50 40 30 20 10 (%) Resilience 0 S1 S2 S3 S4 Modification technique

Fig. 6. Variation of resilience of latex coated coir filled rubber vulcanisates 10

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The structure of neoprene is somewhat strength, elongation at break and tear similar to NR and hence there is not strength. much of a difference between the resilience of S1, S2 and S4 vulcanisates. Aging properties of the latex coated Figure 7 shows that there is a marked coir filled rubber vulcanisates difference between the abrasion volume Table 4 indicates that there is no marked loss of the three compounded latex difference between tensile strength and coated coir filled rubber vulcanisates elongation at break, before and after S2, S3 and S4. S4 is the highest aging at elevated temperatures. abrasion resistance vulcanisate. Generally, results of properties of Abrasion volume loss results also vulcanisates after ageing are low in indicate good adhesion between NR comparison to results of properties latex coated fibre and the NR matrix. before aging due to conversion of The vulcanisate S3 containing nitrile polysulphidic linkages to short mono latex coated coir shows the highest and disulphidic linkages at elevated abrasion volume loss and can be temperatures. Formation of a large attributed to poor adhesion or number of these mono and disulphidic incompatibility between nitrile latex crosslinks would increase the crosslink coated coir and the NR matrix and is in density and hence modulus increase as agreement with the results of tensile indicated from Table 4.

250 ) 3 200

150

100

50

0 (mmloss volume Abrasion S1 S2 S3 S4 Modification technique

Fig. 7. Variation of abrasion volume loss of latex coated coir filled rubber vulcanisates

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Natural rubber composites with surface treated coir

Table 4. Percentage retention of properties of the vulcanisates after aging at 100oC for 22 hrs

Sample Modulus at 300% Tensile strength Elongation at Tear strength (MPa) (MPa) break (%) (KN/m) S1 111 92 92 86 S2 110 95 95 110 S3 102 84 100 100 S4 131 90 87 109

Conclusions rubber composites. International Journal Processing safety of the S4 composite is of Science and Technology Research 2 higher and it is faster curing compared (6), June 2013, 263-271. to the other composites. Further, most De, D, De, D and Adhikari, B (2006). of the physico-mechanical properties of Curing characteristics and mechanical properties of alkali-treated grass-fiber- this composite are superior to those of filled natural rubber composites and the other composites and are at a level effects of bonding agent. Journal acceptable for tyre treads. Hence, the Applied Polymer Science 101, 3151- compounded NR latex coated coir filled 3160. rubber composite could be used in the Farshid, B, Fauziah, A, Ahmad, S Y and manufacture of tyre treads. Mastyra, A (2011). Performance of oil palm empty bunch fibres coated Acknowledgements with acrylonitrile butadiene . The authors would like to thank Laugfs Construction and Building Materials Corporation (Rubber) Ltd., Horana, Sri 25(4), pp.1824-1829. Geethamma, V G, Thomas, Mathew K, Lanka for testing tensile properties and Lakshminarayanan, R and Thomas, S tear strength of the four composites. (1998). Composite of short coir fibers and natural rubber: effect of chemical References modification of fibre. Polymer 39 (6), Ahlblad, G, Kron, A and Stenberg, B 1483-1491. (1994). Effects of plasma treatment on Ismail, H, Jaffri, R and Rozman, H D mechanical properties of rubber/ (2001). Oil palm flour filled cellulose fibre composites. Polymer natural rubber composites: the effect of International 33, 103-109. various bonding agents. International Arumugam, N, Selvy, K T, Rao, K V and Journal Polymeric Material 49, 311, 22. Rajalingam, P (1989). Coconut-fiber- Ismail, H, Shuhelmy, S and Edyham, M R reinforced rubber composites. Journal of (2002). The effects of a silane coupling Applied Polymer Science 37 (9), 2645- agent on curing characteristics and 2659. mechanical properties of bamboo fibre Chigondo, F, Shoko, P, Nyamunda, B C, filled natural rubber composites. UpenyuGuyo and Moyo, M (2013). European Polymer Journal 38, 39-47. Maize stalk as reinforcement in natural 12

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Jacob, M J and Anandjiwala, Rajesh, D Mahato, D N, Mathur, B K and (2009). Lignocellulosic Fiber Reinforced Bhattacherjee S (1993). Radial Rubber Composites, Chap.10 In: Natural distribution function analysis of coir Fibre Reinforced Polymer Composites: fibre. Journal of Materials Science to nanoscales, p.252 (Eds. 28(9), 2315-2320. S.Thomas and Laly Pothen) Old City Mathew, L, Joseph, K U and Joseph, R Publishing. USA. (2004). Isora fibres and their composites Jacob A, Jacob, M and Thomas, S. with natural rubber. Progress in Rubber, Influence of chemical modification on Plastics and Recycling Technology 20, 4, mechanical and swelling characteristics 337-349. of banana fiber reinforced natural rubber Owolabi, O, Czvikovszky T, Kovacs I composites. Journal Applied Polymer (1985). Coconut‐fiber‐reinforced Science (Communicated). thermosetting plastics. Journal of Jacob M, Varughese, K T and Thomas, S Applied Polymer Science 30 (5), 1827- (2004). Mechanical properties of sisal/oil 1836. palm hybrid fiber reinforced natural Prasad, S V, Pavithran, C and Rohatgi, P K rubber composites. Composites Science (1983). Alkali treatment of coir fibres for & Technology 64, 955-965. coir polyester composites. Journal of Joseph, S, Joseph, K and Thomas, S (2006). Materials Science 18(5), 1443-54. Green composites from natural rubber Sakdapipanich, J T (2007). Structural and oil palm fiber: Physical and characterization of natural rubber based mechanical properties. International on recent evidence from selective Journal Polymer Material 55, 925-945. enzymatic treatments. Journal of Khalid, M, Ratnam, C T, Chuah, T G, Ali, S Bioscience Bioengineering 103(4), 287- and Choong T S Y (2008). Comparative 292. study of polypropylene composites Visakh, P M, Thomas, S, Oksman, K and reinforced with oil palm empty fruit Mathew, A P (2012). Effect of cellulose bunch fiber and oil palm derived nanofibers isolated from bamboo pulp on cellulose. Materials & Design 29 (1), vulcanized natural rubber. Bio Resources 173-178. 7(2), 2156-2168. Ku, H, Wang, H, Pattarachaiyakoop, N and Yousif, B F and Tayeb, E N S M (2007). Trada M (2011). A review on the tensile The effect of oil palm fibers as properties of natural fibre reinforced reinforcement on tribological polymer composites. Compos Part B – performance of polyester composites. Eng. 42, 856-73. Polyester Composites Surface Rev. Lett. Lopattananon, N, Panawarangkul, K, 14(6), 1095-1102. Sahakaro, K and Ellis, B (2006). Performance of pineapple leaf fiber- Address for correspondence: Dr (Mrs) D G natural rubber composites: The effect of Edirisinghe, Head, Rubber Technology fiber surface treatments. Journal of Dept., Rubber Research Institute of Sri Applied Polymer Science 102, 1074- Lanka, Telewala Road, Ratmalana, Sri 1084. Lanka. e-mail: [email protected]

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