AN INVESTIGATION ON THE POTENTIAL OF RICE HUSK ASH AS FILLERS FOR EPOXIDIZED NATURAL-RUBBER (ENR)

Burnt rice husk ash yields two grades of fillers, namely white rice hu sk ash, WRHA and black rice husk ash, BRHA. WRHA used in this study ha s been analysed to have about 96% silica content, while the BRHA has a lower silica content, typically about 54%, and a substantial carbon c ontent, i.e. about 44%, These ashes were incorporated into epoxidized natural rubber, ENR (50 mol.% epoxidation grade) using a laboratory si ze two roll mixing mill. Curing using a semi-efficient vulcanization ( semi-EV) was chosen and cure studies were carried out on a Monsanto rh eometer. The physical testing of the ENR vulcanizates involves the det ermination of tensile, tear and hardness properties. The effect of the coupling agent on the curing and physical properties of the vulcaniza tes has been investigated using gamma-mercaptopropyltrimethoxysilane. For comparison purpose, two commercial fillers, i.e. precipitated sili ca (grade Vulcasil-S) and carbon black (grade N330) were used. WRHA ex hibits the best overall vulcanizates properties as compared to BRHA, t hough it is still inferior to commercial fillers especially with regar d to tensile strength and rear strength. The present of the silane cou pling agent has enhanced the cure times (t(90)), tensile and tear stre ngths of filled ENR vulcanizates.