Study of the addition of poly(ethylene-co-methyl acrylate-co-glycidyl methacrylate) thermoplastic to epoxy resin for use in self-healing composites

摘要

Repair of damaged composite structural elements to restore pristine conditions andmeet regulatory requirements can be a great challenge. Thus, materials capable ofself-healing when damaged are of great interest. In one of the self-healingapproaches studied in the literature, thermoplastic is added to a thermosetting matrixand the damaged material partially recovers its mechanical properties after a healingcycle. This technique employs heat to trigger the healing process and partially reestablishthe mechanical properties of the composite material. In the present study,poly(ethylene-co-methyl acrylate-co-glycidyl methacrylate) (E-MA-GMA)thermoplastic was added to epoxy matrix and evaluated as a self-healing agent. Theinfluence of the type of hardener employed (anhydride or amine) on the properties ofthe material was also investigated. Dynamic mechanical thermal analysis (DMTA)was performed to evaluate changes in viscoelastic properties due to the addition ofthermoplastic. Fourier transform infrared (FTIR) spectroscopy was used to evaluatechemical alterations in thermoplastic-epoxy systems. Atomic force microscopy (AFM)was employed to examine the role of thermoplastic addition on epoxy networkstructure. Healing ability was assessed by comparison of areas damaged byindentations on the surface of samples before and after a healing cycle for materialswith and without E-MA-GMA addition. Results suggest the presence of a E-MA-GMAsecond phase after curing, an increase in glass transition temperature (Tg) for allthermoplastic blended samples as compared to neat epoxy, the presence of onesingle Tg for epoxy anhydride hardened E-MA-GMA mixtures and chemical andstructural alterations on the epoxy network due to addition of E-MA-GMA. Further,the elimination of visible damage areas of the material modified with thermoplasticafter a heating cycle supports the potential use of E-MA-GMA as healing agent.