Bio‐Based Chitosan Flexible Reinforcement: Exploring the Synergistic Network Reconstruction Mechanism of Silica‐Chitosan in SSBR Rubber Composites

This study investigates the effects of partially replacing silica with bio‐based chitosan (CTS) on the structure and properties of SSBR rubber composites. The study systematically investigated the Payne effect, rheological behavior, crosslinking density, and static/dynamic mechanical properties of the rubber compound. The filler network evolution and concentration‐dependent behavior of CTS were analyzed. Research indicates that CTS disrupts the rigid silica network, reducing the Payne effect and Mooney viscosity while improving processability. At CTS levels below 15 phr, SSBR exhibits significant enhancements in tensile strength, elongation at break, tear strength, and toughness. When CTS reaches or exceeds 15 phr, the Kraus model fitting accuracy drops sharply, suggesting a possible transition in the filler network behavior; performance degradation is also observed. Research findings indicate that CTS, as a bio‐based flexible reinforcing secondary filler, can enhance the processability and mechanical properties of SSBR through synergistic network restructuring. This study represents a meaningful exploration into the design of reinforcement systems for bio‐based rubber fillers.