Comparison of rubber reinforcement using various surface modified silicas

Abstract

To improve the performance of natural rubber compounds using silica as a reinforcing filler, the silica surface was modified by a four-step process to form an ultrathin film on the solid substrate to produce silica modified with styrene-isoprene copolymers. The reinforcement of a model natural rubber compound was compared for five surface modified silicas, differing in the amount of co-monomer charged to the reactor. The comparative study of compound physical properties showed that the amount of copolymer charge can significantly affect reinforced rubber compound properties. The modified silica having a reactor charge of 20 grams of copolymer per kg of silica produced the greatest improvement in the largest number of properties. This modified silica afforded the maximum in many of the rubber reinforcing properties, including tensile strength, tear strength and resilience, and gave the minimum in compound cure time, compression set and abrasion loss. The effect of ortcent-modified-silica in the rubber compound was also investigated. The results showed that when a reinforcing silica is added to rubber, some tests show a monotonic increase in desirable properties, while still others show a maximum or a minimum with loading.