Self‐Healing Clay/Epoxy Composites Prepared from Clay‐Modified Microcapsules

Urea‐formaldehyde microcapsules were made in the presence of montmorillonite (MMT) nanoparticles by in‐situ polymerization and characterized with different methods. To monitor the presence of MMT and Dicyclopentadiene in microcapsules. Fourier‐transform infrared spectroscopy (FTIR) spectra was taken from samples. Distribution of microcapsule‘s diameters was studied by optical microscopy (OM) micrographs. Size distribution analysis showed that the average diameter of the microcapsules decreased from 130 (in the neat microcapsules) to 85 μm in MMT modified microcapsules. Surface and shell wall of microcapsules have an important role in their capability. Therefore, surface roughness and shell barrier properties were investigated by AFM micrographs and Thermogravimetry analysis. Results of both the methods showed improved features in MMT modified microcapsules. The synthesized microcapsules were used in MMT/epoxy nanocomposite as the healing agent and a coated glass monitored under optical microscope before and after crack demonstrating a good healing observed after 2 hours. Urea‐formaldehyde microcapsules were made in presence of montmorillonite and characterized.IR spectra of neat and MMT microcapsules presented MMT and DCPD in microcapsules. Optical microscopy showed lower average diameter in MMT‐modified microcapsules. Less roughness in MMT‐modified shell wall and better thermal stability and more barrier effect of MMT‐modified microcapsule were resulted from SEM, AFM and TGA analysis. Finally, MMT‐modified microcapsules under the optical microscope showed acceptable repair in 2 hours after crack.