Study on the Shape Memory and Recyclability of Bismaleimide-Strengthened Hydantoin Epoxy Resin Systems

Abstract

As a thermosetting resin, hydantoin epoxy resin can acquire shape memory functionality and reprocessability through the incorporation of a reversible cross-linking network. However, its practical application is constrained by inherent limitations, including sluggish reaction kinetics, inadequate thermal resistance, and suboptimal mechanical strength. To address these challenges, we synthesized a modifier bismaleimide-diamino diphenyl sulfone (BMDS) through the reaction between bismaleimide and 4,4′-diamino diphenyl sulfone. The amine groups in BMDS effectively accelerated the curing process by reducing the reaction activation energy from 69.74 to 67.14 kJ/mol. Remarkably, BMDS modification enhanced the thermal stability of the resin system, elevating its heat resistance index from 174.26 to 179.99 °C and increasing the char yield from 13.39% to 18.21%. Concurrently, mechanical properties showed substantial improvement, with tensile strength rising from 37.2 to 64.7 MPa and flexural strength from 69.9 to 94.8 MPa. Crucially, these enhancements were achieved while preserving the material’s intrinsic shape memory behavior and secondary processability. Furthermore, solvent-recovered BMDS-modified resin demonstrated successful structural reconstruction through secondary curing, facilitated by its dynamic reversible cross-linking network. This approach not only enables efficient material recycling but also maintains shape memory functionality, presenting a viable strategy for developing sustainable thermosetting polymers.