Recyclable High-Strength Epoxy Resin by Polyimine/Glass Modification: Mechanical Reinforcement Mechanisms

The resulting composites exhibit remarkable self-healing properties and enhanced recyclability by incorporating dynamic, reversible polyimine bonds into the epoxy matrix. Subsequently, glass fibers (GF) were modified using 3-aminopropyltrimethoxysilane (APTMS) to improve interfacial adhesion with the epoxy/polyimine matrix. Scanning electron microscopy (SEM) analysis revealed that the modified GFs significantly contribute to mechanical reinforcement through crack bridging, stress transfer, and energy dissipation. Experimental results showed that the addition of APTMS-modified glass fibers (AGF) improved the tensile strength and modulus of the AGF/EP/PI composites. When the content of AGF is 10%, the tensile strength and modulus of the composite reach 63.3 and 301 MPa, respectively, an increase of 27% and 25% compared to the EP/PI matrix. The introduction of AGF also significantly enhances the impact resistance, with the impact strength of the composite containing 5% AGF increased by 43% compared to the matrix. In terms of cycling performance, the EP/PI matrix material demonstrates excellent recyclability. After multiple cycling tests, the overall performance of the AGF/EP/PI composite remains high. It results in excellent cycling performance, providing new design ideas for the development of high-performance, recyclable pressure shell composites.