Development of composites with a self-healing function

This research aimed to realize experimentally the facile vascular self-healing system in epoxy glass fibre reinforced composite. Using flexible polytetrafluoroethylene tubes as removable preforms, the channels were embedded into both neat epoxy resin and unidirectional glass-fibre reinforced epoxy laminate. Room temperature curable epoxy resin with a surfactant and an amine-based hardener were the components of the binary healing agent. The specimens of tapered double cantilever beam geometry were subjected to Mode I fracture tests. Fracture of specimens released the healing agent from channels and triggered self-healing process of the crack. Tested neat epoxy resin specimens demonstrated recovery of fracture toughness ca. 70% after 24 h of self-healing at 50 °C. Unidirectional laminate specimens (250 × 23 × 1.2 mm3) were made by vacuum infusion method from two layers of glass yarns with 5 embedded channels aligning to reinforcing fibers. The channels were alternately filled with components of the healing agent and then sealed. It was revealed that the embedded vascular channels in specimens had very little effect on their elastic modulus. The experimental program included multiple three-point bending tests of specimens for their initial damage and self-healing of specimens during their heat treatment and following exposure at room temperature. Static and dynamic flexural moduli of elasticity were determined by three-point bending and cantilever beam vibration at all stages of the test program. The healing efficiency was evaluated as a relative change of elastic modulus. The efficiency ca. 30% was reached during 24 h at 50 °C and additionally increased up ca. 40% after more than 3 weeks of room temperature exposure. The sealed healing agent was capable of maintaining the capacity for self-healing for at least six months. The research results demonstrated capacity of the macro-channel approach for self-healing realization in multifunctional polymer composite materials.