Toward Replacement of Petroleum Oils By Modified Soybean Oils in Tire Applications

Precipitated silica and carbon black (CB) are the two major reinforcing fillers for rubbers. In this study, silica- and CB-filled styrene-butadiene rubber (SBR) compounds and vulcanizates containing naphthenic oil (NO), soybean oil (SO) and two different levels of modified soybean oil (MSO) were prepared for comparison. Various properties including gel fraction, crosslink density, bound rubber fraction, curing behavior, thermal, mechanical and dynamic properties of silica- and CB-filled SBR were compared. The reaction between the SO, MSO and silane coupling agent was also studied. It was shown that the incorporation of SO and MSO had similar effects in both silica- and CB-filled SBR compounds and vulcanizates. The SO and MSO could consume the curatives leading to a lower crosslink density in both silica- and CB-filled systems. The usage of SO and MSO improves the thermal stability of the silica- and CB-filled SBR compounds and vulcanizates. The MSO is found to increase the elongation at break and tensile strength but decrease the modulus and abrasion resistance in both silica- and CB-filled SBR vulcanizates compared to those of the silica- and CB-filled SBR/NO vulcanizates. The dynamic mechanical analysis showed that the incorporation of MSO could increase the wet traction performance and the rolling resistance in both silica- and CB-filled SBR vulcanizates compared to those of the SBR/NO vulcanizates. After adjusting the recipe, the modulus and abrasion resistance of the silica- and CB-filled SBR/MSO vulcanizates were tremendously increased, and the silica-filled SBR/MSO vulcanizates exhibited a better wet traction performance, a lower rolling resistance and a better abrasion resistance simultaneously than the silica-filled SBR/NO vulcanizate.