Study of In-situ Hybrid Composites of Poly (ethylene terephthalate)/Liquid Crystalline Polymer Filled with Microwave-synthesized Zinc Oxide Powder

This work aims to investigate the system called "in-situ hybrid composites" normally consisting of a thermoplastic, a liquid crystalline polymer, and an inorganic filler. Blends of poly(ethylene terephthalate) (PET) with 10 wt% liquid crystalline polymer (LCP) were filled with zinc oxide powder (ZnO) at 0.5 and 1.0 phr loadings. The ZnO powder was synthesized from zinc nitrate in an aqueous system via microwave irradiation. Melt-blending was conducted in a twin-screw extruder and the compounds obtained were then injection-molded. It was hypothesized that transesterification between the LCP and PET might be promoted by the catalytic activity of ZnO, yielding a composite with better mechanical performance. A reduction in the LCP fibril fraction in the PET matrix, along with a lower shear viscosity, was observed with increasing ZnO loadings. Tensile strength results for the samples filled with ZnO indicated no improvement of the interfacial adhesion between LCP and PET suggesting that the transesterification is not evident. ZnO was found to increase the tensile modulus of the PET/LCP blend. The isothermal and non-isothermal crystallization kinetics of PET were enhanced in the presence of LCP but retarded in the presence of ZnO.