Mechanical properties and crystallization of polybutylene terephthalate reinforced with glass flakes and aluminum powder

This research investigated mechanical properties and crystallization of poly(butylene terephthalate) composites by adding glass flakes (GF) and aluminum particles (Al). The concentration of the GF was 3 wt% or 5 wt%, and the Al was 0.5 wt% or 1.0 wt%. The stress-strain curves of the PBT-based composites showed yielding and necking. The PBT/GF/Al composites with GF/Al ratios of 3/0.5 wt/wt%, 3/1.0 wt/wt%, 5/0.5 wt/wt%, and 5/1.0 wt/wt% had Young’s moduli of 11.44%, 11.70%, 16.81%, and 19.31% higher than that of neat PBT, respectively. In the presence of Al at 1.0 wt%, the flexural modulus of the PBT/GF/Al composites increased to 3.6% higher than that of neat PBT, and all flexure specimens recovered elastically after being subjected to 5% strain. The neat PBT and all PBT/GF/Al composites exhibited the XRD pattern of a-form crystals, in which the changed crystal dimensions implied the heterogeneous nucleation with the presence of these fillers. The cooling rate of the injection molding was so fast that the filler-nucleated crystallization formed only a-form crystals. Adding the GF and Al increased the Tc of the PBT matrix, confirming these fillers acted as nucleating agents. Adding GF/Al fillers of 6 wt% reduced the electrical surface resistivity to 1010 ohm∙sq‒1, indicating it was an anti-static material.