Striking effect of epoxy resin on improving mechanical properties of poly(butylene terephthalate)/recycled carbon fibre composites

Recycled carbon fibre (RCF) reinforced poly(butylene terephthalate) (PBT) composites with high mechanical properties have been prepared through melt compounding. Here three epoxy resins (EP) with different molecular weights and epoxy values were used as in-situ coupling agent to improve the interfacial adhesion between RCF and PBT. The morphologies of impact fractured surfaces were studied to compare the effects of three kinds of EP on the interfacial adhesion between RCF and PBT. The optimal strengthening effect was achieved in the case containing EP with the highest molecular weight. The strengthening mechanism of EP on the mechanical properties of PBT/RCF composites was studied. The results showed that the improved mechanical properties of PBT/RCF composites resulted from the improvement for the interfacial adhesion between PBT and RCF and the in-situ extended chain reaction of PBT matrix with EP.