Multifunctional interfacial regulation of natural rubber, cis-1,4-polybutadiene rubber, and trans-1,4-poly(isoprene-co-butadiene) rubber composites using epoxidized soybean oil

ESO acts as a multifunctional interfacial modifier in NR/BR/TBIR composites. • ESO improves matrix compatibility and filler dispersion in the composites. • Optimal ESO enhances strength, thermal behavior and wear resistance. • Interfacial regulation reduces DIN abrasion and stabilizes wear mechanism. Epoxidized soybean oil (ESO) was employed as a multifunctional interfacial modifier to regulate matrix compatibility, filler dispersion, and interfacial interactions in natural rubber/cis-1,4-polybutadiene rubber/trans-1,4-poly(isoprene-co-butadiene) rubber (NR/BR/TBIR) composites. The effects of ESO on rubber-rubber compatibility, filler network formation, and rubber-filler interfacial adhesion were systematically investigated, together with the resulting mechanical, thermal, and wear-resistant properties. The incorporation of 2.5 phr ESO, significantly reduced the Mooney viscosity difference between NR and BR phases from 56.42 to 51.85 and suppressed the crystallinity of TBIR, with the relative crystallinity decreasing to 74.6%. Owing to its amphiphilic molecular structure, ESO effectively improved filler dispersion, achieving a dispersion degree of 84.34% and an average aggregate size of 7.73 μm, while simultaneously enhancing rubber-filler interfacial adhesion, as evidenced by increased bound rubber content. These interfacial improvements led to a synergistic enhancement of tensile and tear strength, optimized thermal conductivity, reduced compression fatigue heat generation, and significantly improved wear resistance. Notably, the DIN abrasion volume reached a minimum value of 68.8 mm³ at 2.5 phr ESO, which was attributed to the optimized filler network and strong interfacial bonding that suppressed the transition from abrasive wear to rolling wear. Beyond previous ESO-based rubber modification studies that mainly focused on plasticization or compatibilization, this work establishes a bio-based multi-interface regulation strategy that links rubber-rubber compatibility, filler dispersion, rubber-filler adhesion, and wear-resistant performance in multi-component rubber composites. Download: Download high-res image (215KB) Download: Download full-size image