Development and characterization of poly(ethylene terephthalate) based injection molded self-reinforced composites. Direct reinforcement by overmolding the composite inserts

Abstract

This work presents the concept of using the self-reinforced inserts, suitable for overmolding during the standard injection molding procedure. The reinforcing inserts made from self-reinforced poly(ethylene terephtahalte) sheets (srPET) were overmolded by the matrix polymer. Two types of poly(ethylene terephthalate) were used as the matrix material, PET (pure bottle grade resin) and G-PET (amorphous PET based copolymer). Samples prepared under different conditions of the injection molding process were tested in terms of mechanical properties, DMA and DSC analysis. The results of mechanical tests confirmed the different fracture behavior, more favorable for G-PET samples, where the increase of tensile strength and E modulus reached 60% and 32% respectively. The most significant increase was observed for impact resistance values, for both types of polyesters the impact strength reach around 50 kJ/m2, from the initial value below 5 kJ/m2. The SEM microscopy was used to investigate the morphology of matrix-reinforcement interface. The observations of the bonding interface indicate the lack of delamination process and high level of adhesion between the matrix materials and reinforcing srPET insert. The presented results confirm that the proposed concept of using the overmolding technology for preparation of self-reinforced composites has the potential for industrial implementation.