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

Received: 16 June 2010 / Accepted: 23 December 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

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*Corresponding author; email: dia@ukm.my