Thermoplastic healing in epoxy networks: exploring performance and mechanism of alternative healing agents

This paper investigates thermally activated healing in an epoxy amine network using six thermoplastic modifiers; ethylene vinyl acetate (EVA), poly (ethylene-co-glycidyl)-methacrylate (PEGMA), poly(vinyl-butyral) (PVB), styrene-ethylene-butadiene copolymer (SEBS), acrylonitrile-butadiene-styrene (ABS) and polyethylene-co-methacrylic acid (EMAA). They all exhibit healing but varied in efficiency, repeatability and mechanism. EMAA, PEGMA and EVA display superior healing or load recovery compared with ABS, SEBS and PVB with increasing healing events. For EMAA and PEGMA this is attributed to a pressure delivery mechanism, while for EVA, it is attributed to increased viscous flow and a highly elastomeric response to damage. Adhesive binding of the fracture surfaces is also critical in restoring load.