Synergistic Reinforcing Effect of Modified Calcium Sulfate Whiskers and Silica on Styrene‐Butadiene Rubber

ABSTRACT To achieve value‐added utilization of industrial solid waste and develop sustainable rubber reinforcing materials, this paper employed silane coupling agent Si‐69 for surface modification of calcium sulfate whiskers (CSW). The modified whiskers (M‐CSW) were blended with silica to establish a synergistic filler system based on solution‐polymerized styrene‐butadiene rubber (SSBR). Following successful modification, the hydrophobicity of CSW significantly increased, with the contact angle rising from 17° to 126°. Experimental results indicate that at the optimal filler content of 5 phr, compared to composites containing only silica, the modified composite exhibits a 14.3% increase in tensile strength, a 12.2% improvement in elongation at break, and an 8.7% enhancement in tear strength. tan δ at 0°C increased by 2.9% (improved wet traction performance), while tan δ at 60°C decreased by 20.8% (reduced rolling resistance). This approach not only enables effective utilization of industrial solid waste but also enhances the physical and mechanical properties of composites. This study represents a meaningful exploration into the rational application of industrial solid waste (CSW) and holds significant engineering implications.