Effect of Double Bridging of Epoxidized Natural Rubber on the Interface Compatibility of Starch Nanoparticles/Natural Rubber Latex Composites

ABSTRACT To address the issues of significant polarity mismatch and weak interfacial bonding between polar starch nanoparticles (SNPs) and nonpolar natural rubber latex (NRL), epoxidized natural rubber (ENR) was introduced as an interfacial modifier in this work, aiming to optimize the interfacial interactions and comprehensive properties of SNPs/NRL composites. Mechanistic analysis revealed that ENR exerted a unique “bridging” effect: the epoxy groups on its molecular chains formed hydrogen‐bonded physical interactions with the hydroxyl groups on the surface of SNPs, while the carbon–carbon double bonds participated in the co‐vulcanization reaction of the NRL matrix, thereby constructing a dense interfacial cross‐linking network. This dual effect effectively inhibited the agglomeration of SNPs and significantly reduced the interfacial defects within the composites. The experimental results demonstrated that the optimal modification effect was achieved at an ENR loading of 5 phr. Compared with the neat control sample without ENR addition, the tensile strength of the composite was increased by 40.56%, the wet abrasion loss was reduced by 61.58%, the cross‐linking density reached the peak value, and the microscopic morphology of the composite exhibited a high degree of uniformity and densification. This work provides a theoretical basis for the interfacial design of high‐performance NRL‐based composites.