Preparation and self-healing performance of epoxy composites with microcapsules and tungsten (VI) chloride catalyst

Self-healing materials are inspired by biological systems in which damage triggers an autonomic healing response. Epoxy resin-based self-healing system was demonstrated using tungsten (VI) chloride catalyst with a co-activator (phenylacetylene) that initiates ring-opening metathesis polymerization of dicyclopentadiene. The microcapsules with diameter of 200 ± 40 µm and average wall thickness of 5 µm were synthesized. Crack trigger process was analyzed by using finite element methods, the results indicated that the crack will be attracted toward the microcapsules when the wall thickness of microcapsules is in the range of 5–20 µm. The mechanism of tungsten (VI) chloride catalyze polymerization was studied. Environmental stability of tungsten (VI) chloride was investigated. Self-activated and self-healing samples were prepared and the healing efficiency was evaluated. It was found the concentration of catalyst have a significant impact on the virgin properties of the composites and the healing efficiency. The highest healing efficiency 64.9% was obtained with 15 wt% catalyst at self-activated samples. In the case of 10 wt% tungsten (VI) chloride and 10 wt% microcapsules, in situ self-healing sample yielded a healing efficiency of approximately 38.0%.