Thermal and impact study of PP/PET fibre composites compatibilized with Glycidyl Methacrylate and Maleic Anhydride

In this paper, two grafted copolymers, Glycidyl Methacrylate grafted polypropylene (PP) (PP-g-GMA) and Maleic Anhydride grafted PP (PP-g-MA) were used in PP reinforced with short poly(ethylene terephthalate) (PET) fibre composites. Transcrystallization (TC) of PP on PET fibres was investigated using a polarized optical microscope, which revealed no TC for either of the modified composites at the fibre–matrix interface. Heat deflection temperature (HDT) results of GMA modified composites revealed more enhancement than HDT of MA modified samples. The composite strength results showed enhancement for both modified composites up to 10 wt.%, and this growth was bigger for GMA modified composites. The morphological analysis of GMA modified PP/PET composites pointed out a marked improvement of fibre dispersion and interfacial adhesion as compared to non-compatibilized PP/PET composites. The results of impact strength showed about 43% enhancement for 15 wt.% PET fibre composites. It was found that at low fibre percentages, using either of the modifiers reduces the impact strength a little in comparison to impact strength of the unmodified samples. According to linear elastic fracture mechanics LEFM, impact fracture toughness (Gc) and critical stress intensity factor (Kc) were evaluated for these composites based on the fracture energy obtained from impact tests.