Effects of borax loading on the self-healing properties of epoxidized natural rubber

A promising approach for developing self-healing polymer materials involves the formation of reversible dynamic crosslinked networks. However, most self-healing systems require external stimuli such as temperature or pressure, to achieve effective healing. In this study, we successfully developed self-healing epoxidized natural rubber (ENR) materials that do not depend on external stimuli by incorporating borax as a crosslinking agent. The results demonstrated that borax facilitates self-healing efficiency through the reversibility of borate-ester and hydrogen bonds. ENR with 10 phr borax exhibits remarkable self-healing performance, achieving 94% efficiency in tensile strength and 95% efficiency in elongation at break after healing at ambient temperature for 24 h. Moreover, the effect of borax loadings on the chemical structure, thermal stability, and mechanical properties of the crosslinked ENR materials were investigated. These findings highlight the crucial role of borax in imparting self-healing properties to ENR without requiring external stimuli, offering an effective approach for developing self-healing elastomers.