Modified Soybean Oil-Extended SBR Compounds and Vulcanizates Filled with Carbon Black and Silica

Petroleum oil is a common plasticizer for tire rubbers filled with precipitated silica and carbon black (CB). The current trend in tire industry is to replace petroleum oils with modified oils derived from plants, such as soybean oils. The present poster describes results of studies related to utilization of soybean oil norbornylized through the reaction with dicyclopentadiene (DCPD) at various levels in SBR compounds in comparison with usage of naphthenic and unmodified soybean oil. The gel fraction, crosslink density, bound rubber fraction, curing behavior, thermal properties, mechanical and dynamic properties and the possible reactions between the SO, MSO and the silane coupling agent were investigated. Results indicated that the silica- and CB-filled SBR vulcanizates showed a similar trend on behavior of gel fraction and crosslink density for different extender oils. However, the silica-filled SBR compounds showed a lower bound rubber fraction than that of the CB-filled SBR compounds. Both silica- and CB-filled SBR compounds and vulcanizates extended with SO and MSO showed better thermal stability compared to rubbers extended with NO. The silica-filled SBR vulcanizates exhibited a higher M100, a lower tensile strength and similar abrasion resistance than those of the CB-filled SBR vulcanizates. Vulcanizates containing MSO and SO exhibited higher tensile strength and elongation at break than NO containing vulcanizates. An adjustment of the curing recipe provided the silica-filled SBR/MSO vulcanizates exhibiting lower rolling resistance, higher traction and abrasion resistance simultaneously. Usage of MSO in rubbers improves safety in manufacturing of tires.