Dual-Dynamic Sacrificial Networks Enable Durable and Reprocessable Epoxidized Natural Rubber Elastomers

Abstract Conventional elastomer networks can provide mechanical stability but offer limited capacity for network rearrangement and reprocessing. In this work, a sulfur-rich oligomeric crosslinker (S-VBGE) was introduced into epoxidized natural rubber (ENR) to construct a filler-free dual-dynamic network containing reversible hydrogen-bonding associations and sulfur-containing dynamic structures. The optimized ENR-SV15 formulation reached a tensile strength of 14.84 MPa and a toughness of 85.07 MJ·m−3. Based on three independent fatigue crack growth measurements, its apparent fatigue threshold was 310 ± 14 J·m−2, compared with 41 ± 1 J·m−2 for ENR-0. Temperature-dependent stress relaxation and reprocessing experiments indicate thermally activated network rearrangement, while variable-temperature FTIR supports the thermal responsiveness of the hydrogen-bonding associations. Together, these results show that balancing reversible associations, sulfur-containing dynamic structures, and network constraints can improve crack growth resistance while retaining solid-state reprocessability in dry ENR elastomers.