Preparation and evaluation of self‐healing microcapsules for asphalt based on response surface optimization

The purpose of this study is to explore the best preparation process of asphalt self‐healing microcapsules. Response surface design and single factor design were used to optimize the preparation process parameters of asphalt self‐healing microcapsules, and the prediction model of core content was established. The optimal preparation process was determined. The results of response surface design showed that the interaction among emulsifier concentration/reaction temperature, core‐shell ratio/reaction temperature, and pH/reaction temperature had significant effect on the core content of microcapsules; the microcapsules prepared by the optimal process were spherical with an average particle size of 90.19 μm. The results of thermogravimetric analysis (TGA) and heating simulation test showed that the microcapsule can delay the damage of the core in high temperature environment; the results of nanoindentation test showed that the young's modulus and hardness of the microcapsules were about 2.50 and 0.28 GPa, respectively. Finally, the improvement mechanism of self‐healing performance of asphalt by microcapsules was revealed by fluorescence microscope.