Sains Malaysiana 40(9)(2011): 985–992

Kesan Modifikasi Sekam Padi dengan Getah Asli Cecair dan Dedahan Kepada Alur Elektron ke Atas Sifat Mekanik Komposit Nr/Hdpe/Sekam Padi

(Effects of Rice Husk Modification with Liquid Natural Rubber and Exposure to Electron Beam

Radiation on the Mechanical Properties of NR/HDPE/Rice Husk Composites)

Chong Ee Lane, Ishak Ahmad & Ibrahim Abdullah

Pusat Pengajian Sains Kimia dan Teknologi Makanan, Fakulti Sains dan Teknologi

Universiti Kebangsaan Malaysia, 43600 Bangi, Selangor D.E. Malaysia

Dahlan Hj. Mohd

Division Teknologi Pemprosesan Radiasi, Agensi Nuklear Malaysia, Bangi, 43000 Kajang, Malaysia

Diserahkan: 16 Jun 2010 / Diterima: 23 Disember 2010

ABSTRAK

Serbuk sekam padi (SP) merupakan serabut semula jadi yang boleh bertindak sebagai pengisi penguat dalam adunan getah asli termoplastik (TPNR) NR/HDPE selepas permukaan serbuk dimodifikasikan sewajarnya. Rawatan serbuk SP merangkumi pra-rawatan dengan 5% larutan natrium hidroksida (NaOH), rendaman dalam larutan getah asli cecair (LNR) dan dedahan SP tersalut LNR kepada sinaran electron (EB). Komposit TPNR/SP disediakan secara pengadunan leburan dalam pengadun dalaman pada keadaan yang telah ditentupastikan terlebih dahulu. Morfologi komposit yang dianalisis menggunakan mikroskop elektron imbasan (SEM), menunjukkan taburan zarah pengisi SP termodifikasi adalah homogen dan kewujudan interaksi matriks-zarah. Komposit terisi SP terubahsuai LNR-EB menunjukan perubahan sifat mekanik yang ketara. Nilai maksimum tegasan dan kekuatan impak adalah masing masing 6.7 MPa dan 13.2 kJ/cm2 pada dedahan 20 kGy dos EB, manakala modulus regangan adalah 79 MPa pada dos 30 kGy. Ini menunjukkan terdapat peningkatan interaksi berkesan antara-muka SP dan TPNR bagi SP terwat LNR pada dos 20-30kGy EB. Peningkatan dos EB pada SP tersalut LNR menyebabkan degradasi salutan NR dan meningkatakan interaksi antara zarah SP. Pengaglomerasian zarah SP akan berlaku dan menyebabkan serakan zarah dalam komposit menjadi tidak homogen.

Kata kunci: Getah asli termoplastik; sekam padi; sinaran alur elektron

ABSTRACT

Rice husk (RH) powder is a natural fibre capable of reinforcing natural rubber thermoplastic (TPNR) NR/HDPE composites on specific modification of the particle surface. In this study the modification of RH powder involved pre-treatment with 5% sodium hydroxide (NaOH) solution, soaking in LNR solution and exposure of LNR coated RH to electron beam (EB) irradiation. Preparation of NR/HDPE/RH composites was via melt-mixing in an internal mixer at predetermined conditions. Morphology study of the composites using scanning electron microscope (SEM) showed a homogeneous distribution of modified RH particles and particle-matrix interaction in the composite. Modified RH filled composites exhibited a significant change in mechanical properties. The maximum stress and impact strength were 6.7 MPa and 13.2 kJ/m2, respectively at 20 kGy radiation, while the tensile modulus was 79 MPa at 30 kGy dose. The interfacial RH-TPNR interaction for the LNR-EB treated RH particles had improved in the EB dosage range of 20-30 kGy. However, over exposure to radiation caused degradation of rubber coat and interaction between particles to increase. Agglomeration of filler particles would occur and caused inhomogeneous distribution of filler in the composite.

Keywords: Electron beam irradiation; rice husk; thermoplastic natural rubber

RUJUKAN

Azizan, A., Dahlan, H.M. & Ibrahim, A. 2005. Electron beam cross-linking of NR/LLDPE blends. Iranian Polymer Journal 14: 505-510.

Bessadok, A., Marais, S., Gouanve, F., Colasse, L., Zimmerlin, I., Roudesli, S. & Metayer, M. 2007. Effect of chemical treatment of Alfa (Stipa tenacissima) fibres on water-sorption properties. Composites Science and Technology 67: 685-697.

Cao, Y., Shibata, S. & Fukumoto, I. 2006. Mechanical properties of biodegradable composites reinforced with bagasse fibre before and after alkali treatments. Composites Part A 37: 423-429.

Colom, X., Carrasco, F., Pages, P. & Canarate, J. 2003. Effects of different treatment on the interface of HDPE/lignocellulosic fiber composites. Composite Science and Technology 63: 161-169.

Dahlan, H.D., Khairul Zaman, M.D. & Ibrahim, A. 2002. Liquid natural rubber (LNR) as a compatibiliser in NR/LLDPE blends -II: the effect of electron-beam (EB) irradiation. Radiation Physics and Chemistry 64: 429-436.

Dahlan, H.M., KhairulZaman, M.D. & Ibrahim, A. 2000. Liquid natural rubber (LNR) as compatibilizer in NR/LLDPE blends. Journal of Applied Polymer Science 78: 1776-1782.

Ibrahim, A. & Zakaria, Z. 1989. Pendepolimeran fotokimia getah asli. Sains Malaysiana 18: 99-109.

Ishak, A. & Lau, P.F. 2006. Effect of PE-g-MA-compatibilizer on the morphology and mechanical properties of 70/30 HDPE/ENR blends. Polymer-Plastics Technology and Engineering 45: 735-739.

Ishak, A., Din, N.A., Mohamad, A., Aziz, A.A. & Abdullah, A. 2005a. Penambahan gentian aramid (twaron) dalam adunan NR/LLDPE dan ENR/LLDPE terhadap sifat mekanik komposit. Sains Malaysiana 34: 57-61.

Ishak, A., Norliza, A.L. & Ibrahim, A. 2005b. Effect of clay and LNR on mechanical properties and morphology of NR/HDPE-Aramid Composites. Polymer Journal 37: 866-869.

Ishak, Z.A.M., Aminullah, A., Ismail, H. & Rozman, H.D. 1998. Effect of silane based coupling agents and acrylic acis based compatibilizers on mechanical properties of oil palm empty fruit bunch fiber filled high-density polyethylene composites. Journal of Applied Polymer Science 68: 2189-2203.

Joseph, K., Thomas, S. & Pavithran, C. 1996. Effect of chemical treatment on the tensile properties of short sisal fibre-reinforced polyethylene compsites. Polymer 37: 5139-5149.

Marcovich, N.E., Aranguren, M.I. & Reboredo, M.M. 2001. Modified woodflour as thermoset fillers Part I. Effect of the chemical modification and percentage of filler on the mechanical properties. Polymer 42: 815-825.

Mwaikambo, L.Y. & Ansell, M.P. 2002. Chemical modification of hemp, sisal, jute and kapok fibers by alkalization. Journal of Applied Polymer Science 84: 2222- 2234.

Ndazi, B.S., Karlsson, S., Tesha, J.V. & Nyahumwa, C.W. 2007. Chemical and physical modifications of rice husks for use as composite panels. Composites Part A 38: 925-935.

Nielsen, L.E. & Landel, R.F. 1994. Mechanical Properties of Polymers and Composites. New York: Marcel Dekker.

Prasad, P.N., Mark, J.E., Kandil, S.H. & Kafafi, Z.H. 1998. Science and Technology of Polymers and Advanced Materials. New York: Plenum Press.

Qin, C., Soykeabkaew, N., Xiuyuan, N. & Peijs, T. 2008. The effect of fibre volume fraction and mercerization on the properties of all-cellulose composites. Carbohydrate Polymers 71: 458-467.

Rout, J., Misra, M., Tripathy, S.S., Nayak, S.K. & Mohanty, A.K. 2001. The influence of fibre treatment on the performance of coir-polyester composites. Composites Science and Technology 61: 1303-1310.

Sahrim, A., Ibrahim, A., Sulaiman, C.S., Kohjiya, S. & Yoon, J.R. 1994. Natural rubber-HDPE blends with liquid natural rubber as compatibilizer. I. Thermal and mechanical properties. Journal of Applied Polymer Science 51: 1357-1363.

Siti, S.S. & Yusof, A. 2003. Ground rice husk as filler in rubber compounding. Jurnal Teknologi 39(A): 135-148.

Suzeren, M., Ahmad, I. & Ibrahim, A. 2006. Effects of rice husk filler on the mechanical and thermal properties of liquid natural rubber compatibilized high-density polyethylene/ natural rubber blends. Journal of Polymer Research 13: 315-321.

Tserki, V., Matzinos, P., Kokkou, S. & Panayiotou, C. 2005. Novel biodegradable composites based on treated lignocellulosic waste flour as filler. Part I. Surface chemical modification and charaterization of waste flour. Composites: Part A 36: 965-974.

Vijayabaskar, V., Bhattacharya, S., Tikku, V.K. & Bhowmick, A.K. 2004. Electron beam initiated modification of acrylic elastomer in presence of polyfuntional monomers. Radiation Physics and Chemistry 71: 1045-1058.

Wambua, P., Ivens, J. & Verpoest, I. 2003. Natural fibres: can they replace glass in fibre reinforced plastics. Composites Science and Technology 63: 1259-1264.

Wong, S., Shanks, R. & Hodzic, A. 2004. Interfacial improvements in poly(3- hydroxybutyrate)-flax fibre composites with hydrogen bonding additives. Composite Science and Technology 64: 1321-1330.

Zsigmond, B., Halasz, L. & Czvikovszky, T. 2003. Electron beam processing of fibre reinforced braided composites Radiation Physics and Chemistry 67: 441-445.

*Pengarang untuk surat-menyurat; email: dia@ukm.my