Effect of room-temperature annealing on structures and properties of SSBR/BR blends and SSBR/BR/SiO2 composites

Room-temperature annealing process lies between high-temperature mixing process and high-temperature vulcanization process in rubber processing technology, and definitely affects the performances of rubber composites. In this work, the influences of room-temperature annealing on the structures and properties of unfilled SSBR/BR blends and silica-filled SSBR/BR composites have been evaluated in detail. For the unfilled SSBR/BR vulcanizates, the tensile strength, tear strength and fatigue resistance deteriorate due to the reduced rubber matrix strength with lower crosslinking density and less chain entanglements with annealing time extending. While for the SSBR/BR/SiO2 vulcanizates with dual networks including filler-filler networks and polymer-polymer networks, the tensile strength and fatigue resistance reduce, the tear strength, dynamical properties concerning abrasion, heat built-up and rolling resistance improve obviously with extending annealing time, which are attributed to the enhanced filler-polymer interactions, severe silica flocculation, and reduced internal hysteresis loss with annealing time prolonging. This work is expected to provide fundamental understanding of the annealing process in the rubber processing technology for development of high-performance rubber composites.