Self-healing thermoset using encapsulated epoxy-amine healing chemistry

Self-healing was achieved with a dual-microcapsule epoxy-amine chemistry in thermoset epoxy. One capsule contained a modified aliphatic polyamine (EPIKURE 3274) while the second capsule contained a diluted epoxy monomer (EPON 815C). Amine microcapsules were prepared by vacuum infiltration of EPIKURE 3274 into hollow polymeric microcapsules. Epoxy microcapsules were prepared by an in situ polymerization method. Both types of capsules were incorporated into an epoxy matrix (EPON 828:DETA) and recovery of mode-I fracture toughness was measured using tapered-double-cantilever-beam (TDCB) specimens. The optimal mass ratio of amine: epoxy capsules was 4: 6 and an average healing efficiency of 91% was achieved with 7 wt% amine capsules and 10.5 wt% epoxy capsules. Long-term stability of the healing system was demonstrated for six months at ambient conditions. Thermal stability was investigated by post curing samples at 121 °C and assessing healing performance.