Evaluation of 5-Ethylidene-2-Norbornene with an Adhesion Promoter for Self-Healing Applications

Abstract

5-Ethylidene-2-norbornene (ENB) has a potential application as part of a new generation of healing agents, owing to its rapid polymerization rate and wide liquid temperature range. In this study, we developed a new self-healing system using ENB as the healing agent and methyl 5-norbornene-2-carboxylate (MNC) as the adhesion promoter. Dynamic differential scanning calorimetry (DSC) was used to monitor cure behaviors of ENB with different MNC loadings, through which a series of cure temperatures were designed. The MNC loading and cure temperature had significant effects on the adhesion strength. The adhesion strength increased remarkably with MNC loadings of up to 10 wt % compared with ENB alone. The ENB monomer and the ENB/MNC mixture were successfully microencapsulated, and the resultant microcapsules were embedded into an epoxy resin along with Grubbs' catalyst for self-healing efficiency measurements. Peak fracture loads for both healing agents showed maximal values at a low catalyst loading (0.3 wt %). In comparison with neat ENB, a significant improvement in healing efficiency was observed for the ENB/MNC mixture. (C) 2016 Wiley Periodicals, Inc.