Sains Malaysiana 40(7)(2011): 743–748

Effect of Molecular Weight on the Properties of Liquid Epoxidised Natural

Rubber Acrylate (LENRA)/Silica Hybrid Composites

(Kesan Berat Molekul ke Atas Sifat-sifat Komposit Hibrid Getah Asli

Terepoksida Berakrilat Cecair (LENRA)/Silika)

Eda Yuhana Ariffin* & Azizan Ahmad

School of Chemical Sciences and Food Technology, Faculty of Science and Technology

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

Dahlan Hj Mohd, Mahathir Mohamed

Radiation Processing Technology Division (BTS), Malaysian Nuclear Agency, Bangi

43000 Kajang, Selangor D.E., Malaysia

Received: 23 October 2009 / Accepted: 25 September 2010

ABSTRACT

This paper reports on the effect of molecular weight on the morphological and mechanical properties of liquid epoxidised natural rubber acrylate (LENRA)/silica hybrid composites prepared by sol-gel technique. The sol-gel reaction was conducted at different concentration of tetraethylorthosilicate (TEOS), used as a precursor of silica. TEOS were introduced in 10, 20, 30, 40 and 50 parts per hundred rubber (phr) in the composites. Two different molecular weights of ENR were used to study the effect of molecular weight on the mechanical and morphological properties of the compounds. These compounds were cured by ultraviolet (UV) irradiation. The mechanical properties were studied through pendulum hardness and scratch tests. Higher molecular weight of ENR showed better mechanical properties than lower molecular weight. Transmission electron microscope was used to determine the silica size and to study the distribution and dispersion of the silica particles. High molecular weight showed greater distribution and dispersion of silica particles with diameter of 13 nm–256 nm. Morphological and mechanical properties of LENRA/silica hybrid composites were improved by using high molecular weight of ENR.

Keywords: Epoxidised natural rubber; molecular weight; organic-inorganic hybrid; sol-gel technique

ABSTRAK

Kajian ini adalah mengenai kesan berat molekul terhadap sifat mekanik dan morfologi komposit hibrid getah asli terepoksida berakrilat cecair (LENRA)/silika, menggunakan teknik sol-gel. Tindak balas sol-gel dilakukan pada kepekatan tetraetilortosilikat (TEOS) yang berbeza, yang digunakan sebagai bahan pemula silika. TEOS dimasukkan sebanyak 10, 20, 30, 40 dan 50 bahagian per seratus getah (phr) dalam komposit. Dua berat molekul ENR yang berbeza digunakan untuk mengkaji kesan berat molekul terhadap sifat mekanik dan morfologi komposit. Komposit ini dimatangkan dengan menggunakan sinaran ultralembayung (UV). Sifat mekanik diuji melalui ujian kekerasan pendulum dan ujian calaran. Berat molekul ENR yang tinggi menunjukkan sifat mekanik yang lebih baik berbanding berat molekul ENR yang rendah. Mikroskop elektron transmisi digunakan untuk mengukur saiz silika dan mengkaji taburan partikel silika. Berat molekul yang tinggi menunjukkan taburan partikel silika yang lebih baik dengan diameter partikel dalam julat 13 nm-256 nm. Sifat mekanik dan morfologi komposit hibrid LENRA/silika dapat dibaiki dengan menggunakan berat molekul ENR yang tinggi.

Kata kunci: Berat molekul; getah asli terepoksida; hibrid organik-inorganik; teknik sol-gel

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*Corresponding author; email: edayu_hanna@yahoo.com