Improving the abrasion resistance of “green” tyre compounds

Since the introduction of “Green Tyres” in the early 90’s, the use of silica as a reinforcing filler, along with a silane coupling agent, has spread and grown worldwide. The greatest advantage of using silica over carbon black as a reinforcing filler in a tyre tread compound is that a lower rolling resistance is achieved, while maintaining good wet traction. However, a previous study has shown that the wear resistance of a silica filled epoxidised natural rubber (ENR) compound was not as high as those of conventional Oil Extended Styrene Butadiene rubber (OESBR) and NR/BR compounds used in passenger car and truck tyre treads. In this work, with the aim of improving abrasion resistance, the effect of blending Butadiene rubber (BR) into a silica filled ENR compound was studied. Blends with 0 to 30 phr BR were prepared in a Polylab Haake internal mixer. The rheological properties of the compounds were measured using a Mooney viscometer and Oscilating Disc Rheometer. The hardness, tensile strength and DIN abrasion resistance were also measured. The results showed that the ENR/silica compound properties such as tensile strength and hardness were as good as those of the conventional compounds. However, the most important finding was that abrasion resistance increased significantly with BR content, exceeding that of the conventional compound at BR:ENR ratios of greater than 20:80.