Preparation and characterization of self-healing microcapsules embedding waterborne epoxy resin and curing agent for asphalt materials

In this paper study, two kinds of self-healing microcapsules embedding waterborne epoxy resin (WER) and curing agent (CA) are synthesized by using the interfacial polymerization method, which could be incorporated into asphalt binders to prepare the novel self-healing materials and have the potential application to repair the micro-damage and micro-crack in asphalt materials. The two capsule-core materials were emulsified by using different emulsifier dosage and emulsification time, and the normal distribution characteristics of the particle size and quantity were statistically analyzed to determine the optimal emulsification solution. Then, ethylene glycol and toluene diisocyanate (TDI) were selected as the capsule-wall raw materials, and the microcapsules were prepared by using different core-wall materials ratio. The particle dispersion, surface morphology and coating properties were statistically analyzed to determine the optimal synthetization. FT-IR analysis results demonstrated that the microcapsules were successfully prepared by suing those optimized schemes. The optimal synthetization of WER microcapsules that 0.5% emulsifier dosage, emulsification for 16 min, core-wall materials ratio of 1.3:1, and the optimal synthetization of CA microcapsules is that 0.7% emulsifier dosage, emulsification for 16 min, core-wall materials ratio of 1:1. SEM and TG-DSC analysis results showed that the microcapsule particles were uniform, well-dispersed and regular in shape, and the capsule-wall thickness was about 1.0 μm. The thermal stability of the WER microcapsules is better than the CA microcapsules.