Effect of microcapsules doping on DC flashover and trap level of self-healing epoxy resin composites

Minor physical defects can decrease the dielectric efficiency of epoxy resin and severely threaten the electrical device's dependability. Self-healing may be considered an effective method to preserve the electrical and mechanical properties of the epoxy resin. Besides, self-healing significantly decreases the influence of small physical destruction on the power system. In this research, epoxy resin incorporated with various concentration of microcapsules was prepared. The polyurea formaldehyde (PUF) microcapsules were treated using a silane coupling agent (KH550) to enhance dispersion. Moreover, the self-healing performance of the epoxy resin incorporated with microcapsules was analyzed by FTIR, SEM, and DC Flashover in air and vacuum. In addition, trap energy and trap density were obtained from measurements of surface potential decay (ISPD). The SEM results indicate that in comparison with pure epoxy resin, the microcapsule/epoxy resin composite has an improved self-healing performance. The DC Flashover of epoxy resin in air and vacuum was found relatively higher after incorporation of microcapsules than pure epoxy resin. The distribution of trap energy and trap density measured by surface potential decay measurements confirms that 5 wt% have deeper traps and the highest trap energy levels.