Self-healing microcapsules modified by montmorillonite for modulating slow-release properties

Slow-release type self-healing microcapsules (RHM) are fabricated by the solvent evaporation process with a core of epoxy resin (E-44 and E-51) modified by montmorillonite and a wall of ethyl cellulose (EC). Rotational rheometer, environmental scanning electron microscope, high performance liquid chromatography, and UV–vis spectrophotometer are utilized to characterize the composite viscosity, microscopic morphology, encapsulation rate, and slow-release performance, while the rate of strength healing is utilized to characterize the healing performance. The results demonstrate that the viscosity of epoxy resin (E-44 and E-51) can be improved effectively and the sensitivity of its viscosity to temperature can be reduced when epoxy resin (E-44 and E-51) is modified by montmorillonite. There is a good appearance in RHM. With the addition of montmorillonite, the encapsulation rate of the microcapsules increases slightly, while the rate of slow-release decreases gradually. When montmorillonite doped at 9% of E-44, the cumulative release of RHM is 121%, which is lower compared to E−51 RHM at 48 h. The strength healing rate of cement-based materials increases firstly and then decreases with the increasing montmorillonite doping. The RHM modified by E-44 with 6% montmorillonite could reache a maximum strength healing rate of 34.4%. Slow-release type self-healing microcapsules with epoxy resin (E-44 and E-51) modified by montmorillonite (RHMM) can better regulated the slow-release characteristics and have a more significant effect on cement-based self-healing materials.