Synthesis and reaction mechanism of self-healing epoxy microcapsules

Abstract

Self-healing epoxy resin microcapsules are prepared by interfacial polymerization, in which the core materials are epoxy resin, the wall materials are constructed with triethylenetetramine (TETA) and the epoxy resin. The orthogonal experiments L9 (34) are designed to investigate the influence of emulsifier dosage, hardener dosage, curing temperature and hardener adding rate on the core content and storage life of epoxy resin microcapsule. Scanning electron microscope and static dynamic wide angle laser light scattering instrument synchronization are used to characterize surface topography, particle size and distribution. Fourier transform infrared spectroscopy and thermo-gravimetric analyzer are used to study reaction mechanism of the microcapsule wall materials and thermal stability of the microcapsules, respectively. The results indicate that when the dosage of emulsifier is 1.2%, the dosage of hardener is 1.2%, the hardener droplets adding rate is 1.2 g/h and the curing temperature is 50 °C, the microcapsules prepared are spherical in shape with good surface compactness, dispersibility and thermal stability and the capsule core content is 82.3% and the average particle size is 275.3 μm. However, this type of epoxy resin microcapsule has relatively poor chemical stability. The core content decreases by 2.0% after 12 d storedat room temperature. After epoxy resin composite doped with 2.0% mass fraction of 200~300 μm microcapsules is damaged by the tensile testing machine, their repair rate is 67.04%.