Tailoring Rubber-based Shoe Outsole Compounds: Impact of Blend Composition and Filler Type on Slip Resistance and Tribological Performance

This study develops and evaluates advanced rubber outsole compounds reinforced with carbon black (CB) or silica to improve slip resistance and wear durability. Ternary blends of styrene-butadiene rubber (SBR), butadiene rubber (BR), and natural rubber (NR) formed the matrix, with epoxidized NR (ENR) substituting NR in select formulations. Rheological, mechanical, and tribological properties were comprehensively evaluated to examine the effects of blend composition, filler type, and ENR incorporation. CB-filled compounds demonstrated higher cross-link density and enhanced filler networking, yielding superior dry traction. In contrast, silica-filled formulations exhibited improved wear resistance and wet grip, attributed to increased flexibility and energy dissipation. Distinct wear patterns reflected filler morphology. Two optimized formulations were scaled up into full-shoe prototypes and tested using the SATRA TM144:2021 method. Both exceeded industry slip-resistance benchmarks, with the silica-filled outsoles delivering superior wet-traction performance. This work presents a scalable design strategy for high-traction, wear-resistant footwear, well-suited for demanding environments.