Thermal mending in E-glass reinforced poly(ε-caprolactone)/epoxy blends

Blends of difunctional epoxy monomer with a 4,4′-diaminodiphenylsulfone hardener and poly(ε-caprolactone) (PCL) were used as a self-healing matrix in woven glass fibre-reinforced polymer composites (FRPs). FRPs with these blends (containing 0, 25 and 37 vol% of PCL in the blend) were manufactured through Vacuum Assisted Resin Infusion Moulding at high temperature and the matrix, resulting from polymerization induced phase separation, consisted of interconnected epoxy particles embedded in PCL. With 25 vol% PCL in the matrix, similar storage modulus and interfacial shear strength as compared to unmodified systems have been observed, however toughness was decreased by 40%. Up to 45% toughness recovery and over 100% stiffness recovery were observed over several cycles when the blend matrix composite samples were re-tested after a thermal cycle at 150 °C for 30 min. These composites can thus provide efficient crack healing, but remain more sensitive to initial crack propagation due to confinement of the thermoplastic phase.