Effects of dual component microcapsules of resin and curing agent on the self-healing efficiency of epoxy

Dual component microcapsules of diglycidyl ether of bisphenol A epoxy (DGEBA) (resin) and polyetheramine (hardener) for the self-healing agencies of epoxy were prepared by a water-in-oil-in-water emulsion solvent evaporation technique with the polymethyl methacrylate (PMMA) shell. The chemical structure and morphologies of the microcapsules were confirmed using Fourier-transform infrared spectroscopy (FT-IR) and scanning electron microscopy (SEM), respectively. The thermal characteristics of the microcapsules were investigated using thermo-analytical techniques such as differential scanning calorimetric (DSC) and thermogravimetric analysis (TGA). Dual components microcapsules of resin and curing agent were embedded into the epoxy matrix and the healing behavior of the system was studied. About 43.5% healing efficiency was achieved with 5 wt.% microcapsules and 84.5% healing efficiency was achieved with 15 wt.% microcapsules at room temperature for 24 h curing. The healing efficiency of the composite with the dual component microcapsules was higher than that of the composite with the single component healing microcapsule due to the easy reaction between the liquid resin and the liquid hardener at the crack surface. The tensile strength of the epoxy with dual component microcapsules increased initially with increasing the content of microcapsules and reached the maximum at 5 wt.%. Above this point, the tensile strength decreased gradually with increasing. (C) 2013 Elsevier Ltd. All rights reserved.