Studies on Blends of Natural Rubber and Butadiene Rubber Containing Silica –Organomodified Kaolin Hybrid filler Systems

Abstract

Hybrid filler systems consisting of precipitated silica and kaolin modified with a sodium salt of rubber seed oil (SRSO) were studied in blends of natural rubber (NR) and polybutadiene rubber (BR). Substitution of 5–10 phr (parts per hundred rubber) of silica with SRSO modified kaolin imparted lower Mooney viscosity and higher cure rate for the mixes, thereby improving processing characteristics. Higher chemical crosslink density index and bound rubber content of the blends containing SRSO modified kaolin showed a higher extent of rubber–rubber and rubber-filler interaction respectively. The lower abrasion loss and compression set and higher tensile strength, elongation at break and tear strength of the blend rubber vulcanizates containing SRSO modified kaolin indicated its potential for application as tire tread compositions. Also, lower value of loss factor (tan ɗ) of these compositions as measured from DMTA could lead to lower heat build-up in tire tread applications.