(A) study on reactive blend of thermotropic liquid crystalline polymer and poly(ethylene terephthalate)

Abstract

In order to study the effect of chemical reactions on the properties of poly(ethylene terephthalate)[PET] by reactive blending with liquid crystalline polymer[LCP], blend of PET with the copolyester of PHB60/PET were prepared and investigated. Prior to study on reactive blending, several characterization of pure LCP were performed to understand the physical properties and characteristics of the copolyester of PHB60/PET. The LCP, Novaccurate E310 were characterized using gel permeation chromatography(GPC) and nuclear magnetic resonance(NMR) spectroscopy. Moreover, physical properties of the LCP were studied by differential scanning calorimetry(DSC), polarized light microscopy(PLM) and rheological measurement. From the $^1H$-NMR analysis on the LCP, the copolyester revealed different chemical environment compared with corresponding copolyesters of Rodrun LCP3000 and X-7G. The LCP showed very weak endotherm and slow crystallization process due to copolymerization defects from the DSC study. When the LCP was annealed at temperatures below the crystal-nematic transition temperature, it caused an improvement of the ordered structure but exhibits no signs of transesterification and increase in molecular weight. Polarized light microscopy revealed that the LCP is not uniform but forms a morphology with two distinct phase. The copolyester, E310 has biphasic structures over the wide range of temperatures and the rheological response was strongly affected by the relative fraction of nematic and isotropic phase. Isothermal time sweep measurement were performed to study the rheological stability of the LCP at several temperatures. From the preliminary study of thermal behaviors for physical blends of PET/LCP, the thermal behavior showed strong dependence on LCP content. The LCP enhance crystallization of PET matrix in the PET-rich blend while LCP-rich blend shows delayed crystallization and severe melting temperature depression. It was confirmed that there is a specific int...