Student Colloquium Paper
Carbon black (CB) and precipitated silica are two major reinforcing fillers in rubbers. CB/silica hybrid filler is also widely used in rubbers to provide balanced properties. CB/silica hybrid filler-filled SBR compounds and vulcanizates containing naphthenic oil (NO), soybean oil (SO), and norbornylized SO (NSO) are investigated. Swelling and curing behavior, rheological, mechanical, thermal, aging, and dynamic properties are studied and compared with earlier reported data on CB- or silica-filled SBR. It is found that the addition of SO and NSO increases the gel fraction, but decreases the crosslink density of SBR vulcanizates. NSO provides better scorch safety and faster cure than SO. The addition of SO and NSO to hybrid filler-filled SBR enhances the thermal stability and aging resistance of SBR vulcanizates compared with respective SBR/NO vulcanizates. The SBR/NSO vulcanizates with hybrid filler exhibit a higher tensile and tear strength than those of the hybrid filler-filled SBR/NO and SBR/SO vulcanizates. Synergistic effect in vulcanizates containing the hybrid filler is observed for abrasion resistance. An increase of sulfur content provides the hybrid filler-filled SBR/NSO vulcanizates with improved abrasion resistance and loss tangent values predicting improved wet traction and rolling resistance.