Mode II fracture toughening and healing of composites using supramolecular polymer interlayers

This study focuses on the transfer of the healing functionality of supramolecular polymers (SP) to fibre reinforced composites through interleaving. SPs exhibiting self-healing based on hydrogen bonds were formed into films and were successfully incorporated into carbon fibre composites. The effect of the SP interleaves on in-plane fracture toughness and the subsequent healing capability of the hybrid composites were investigated under mode II fracture loading. The fracture toughness showed considerable increase since the maximum load (P _max ) of the hybrid composite approximately doubled, and consequently the mode II interlaminar fracture toughness energy (G _IIC ) exhibited an increase reaching nearly 100% compared to the reference composite. The healing component was activated using external heat. P _max and G _IIC recovery after activation were measured, exhibiting a healing efficiency after the first healing cycle close to 85% for P _max and 100% for G _IIC , eventually dropping to 80% for P _max while G _IIC was retained around 100% even after the fourth healing cycle. Acoustic Emission activity during the tests was monitored and was found to be strongly reduced due to the presence of the SP.