Sains Malaysiana 38(3): 381-386(2009)

Pengisian Sekam Padi dan Tanah Liat ke dalam Matriks Polietilena Berketumpatan Tinggi-Getah Asli-Getah Asli Cecair

(Rice Husk and Clay Loadings into High Density Polyethylene-Natural

Rubber-Liquid Natural Rubber Matrix)

Ishak Ahmad*, Mohd Suzeren Jamil & Ibrahim Abdullah

Pusat Pengajian Sains Kimia dan Teknologi Makanan

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

Received: 30 January 2008 / Accepted: 8 October 2008

Abstrak

Kesan penambahan pengisi sekam padi dan tanah liat ke dalam matriks  getah asli  getah asli cecair polietilena berketumpatan tinggi (NR/LNR/HDPE), NR/HDPE dan HDPE  terhadap sifat mekanik dan morfologi adunan telah dikaji. Pemprosesan adunan dilakukan pada suhu 140 ^oC dan kadar percampuran 50 r.p.m. selama 16 minit. Pra-pemanasan pengisi selama 4 minit pada suhu 80 ^oC dilakukan sebelum pengadunan dengan matrik bagi meminimumkan kesan lembapan. Getah asli cecair digunakan sebagai agen pengserasi dalam adunan komposit. Pengisian sekam padi (SP) dan tanah liat (TL) dalam matriks HDPE, NR/HDPE serta NR/LNR/HDPE umumnya menurunkan nilai kekuatan tensil dan kekuatan hentaman tetapi meningkatkan nilai modulus. Kehomogenan adunan komposit berpengisi yang dikenalpasti melalui pemeriksaan morfologi menggunakan mikroskop imbasan elektron (SEM) menunjukkan masalah aglomerasi dan interaksi antara muka dalam komposit berlaku. Kelikatan leburan dan interaksi antara bahan menentukan arah pergerakan serta serakan pengisi dalam komposit. Daripada keputusan yang diperolehi dan merujuk kedua-dua sifat pengisi, SP adalah lebih serasi dengan NR disebabkan potensi interaksi antara kumpulan berfungsi permukaan pengisi selulosa (SP) seperti –OH dengan ikatan ganda dua NR berbanding TL. Ciri fizik permukaan TL yang kurang bersifat hidrofilik berbanding SP pula menyebabkan TL  lebih cenderung berinteraksi dan tersebar dengan baik dalam HDPE.

Kata kunci:  Adunan polimer; getah asli; polietilena; sekam padi

ABSTRACT

The effects of filling rice husk and clay into high density polyethylene liquid natural rubber natural rubber (HDPE/LNR/NR), NR/HDPE and HDPE matrix on the mechanical and morphological properties of the blend were investigated. Blending of the mixture was done 140^oC and a mixing rate of 50 r.p.m. for 16 minutes. Preheating of the fillers was done for 4 minutes at 80^oC before loading with the matrix to minimize the effect of moisture. Liquid natural rubber was used as a compatibilizer in some blends.  The addition of rice husk (SP) and clay (TL) into the  HDPE, NR/HDPE and NR/LNR/HDPE matrixes, caused the tensile and impact strength to decrease but the modulus and hardness to increase. The filler distribution in the composites was determined by scanning electron microscope (SEM) which showed that the weak inter-phase interaction led to agglomeration in the composites. The viscosity and interaction between the phases in the blend will affect the movement and distribution of filler in the composites. Based on the results and the properties of both fillers, SP is more compatible with NR because of the potential interaction between the functional groups like –OH at the cellulose surface with the double bonds of NR as compared to the inert interaction between clay and NR. However, the physical nature of the TL surface which is less hydrophilic as compared to SP, caused TL particles to have better interaction and well dispersed in HDPE.

Keywords:  Natural rubber; polyethylene; polymer blend; rice husk

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*Corresponding author; email: gading@ukm.my