Molecular dynamics simulation on the intelligent repair behavior of microencapsulated resin matrix composites

Abstract

Microencapsulated resin matrix composites have attracted wide attention for their ability to intelligently detect and repair microcracks, whereas the interaction mechanism between the repair agent and resin after the microcapsules crack has not been well understood. To reveal the repair mechanism of composites containing linseed oil microcapsules, the molecular model consisting of the oxidized linseed oil, microcracks, and cross-linked resin was established based on the molecular dynamics (MD) technique. The intelligent repair process of the models was analyzed. The repairing performance was evaluated by means of elastic modulus, adhesion energy, and interfacial thickness. The influence of temperature and the type of repair agent on repairing performance was studied. The results show that the increased temperature can significantly enhance the diffusion rate of the repair agent molecules and shorten the time for them to reach the crack surface. The changing rate of mechanical properties dramatically increases after 100 ps, and van der Waals energy has a great contribution to the repairing efficiency. The adhesion energy and the interfacial thickness between the components show a trend towards increasing and then decreasing as the temperature increases, and the oxidized linseed oil has a stronger twisting effect with the resin matrix compared with pure resin and cross-linked resin. These findings help understand the intelligent repair behavior of composites on the atomic scale, providing a reference for the design of intelligent composites.