Miscibility study on blend of thermotropic liquid crystalline polymers and polyester

摘要

The miscibility of thermotropic liquid crystalline polymers (TLCPs) and polyester blends was investigated with thermal and morphological analyses, as well as transesterification. TLCPs composed of 80 mol % para-hydroxybenzoate (PHB) and 20 mol % poly(ethylene terephthalate) (PET) or 60 mol % PHB and 40 mol % PET, and polyesters such as PET and poly(ethylene 2,6-naphthalate) (PEN) were melt blended in an internal mixer. DSC analyses were performed to investigate the thermal transition behavior and to obtain thermodynamic parameters. All the blends showed only a single glass-transition temperature, which means they are partially miscible in the molten state. The Flory-Huggins interaction parameter was calculated employing the Nishi-Wang approach, and negative values were obtained except for the P(HBS-ET2)/PEN blends. Transesterification was investigated using H-1-NMR, and the change of chemical shift compared to pure PET or P(HB-ET)s was observed in the P(HB-ET)/PET blends. An intermediate chemical shift value (4.83 ppm) was observed in the P(HB6-ET4)/PEN blends, which indicates transesterification occurred. The fractured surface morphology of scanning electron micrographs showed that the interfaces between the LC droplets and matrix were not distinct. (C) 2003 Wiley Periodicals, Inc. [References: 51]