Self-healing of poly(ethylene-co-methacrylic acid) copolymers following projectile puncture

Several poly(ethylene-co-methacrylic acid) copolymers have shown the unique ability to self-heal following projectile puncture, with the punctured site subsequently holding pressures in excess of 3 MPa. Four specific materials (ionomers and non-ionomer copolymers) were examined to determine if ionic interactions are responsible for puncture reversal. A range of novel experiments including peel, projectile, and quantitative post-puncture testing were used to determine that ionic content is not necessary for the healing response. Mechanistically, it was concluded that healing occurs through at least a two-stage process of melt elastic recovery followed by sealing and polymer chain interdiffusion at the damaged site.