Polymer blends based on mesomorphic components, 1. Properties of poly(tetramethylene terephthalate)/poly(decamethylene 4,4′‐terephthaloyldioxydibenzoate) blends

Abstract

Abstract Blends of poly(tetramethylene terephthalate) [poly(butylene terephthalate) (PBT)] with a liquid crystalline polyester, poly(decamethylene 4,4′‐terephthaloyldioxydibenzoate) (HTH 10), obtained by solution precipitation, were characterized by optical microscopy, X‐ray diffraction and differential calorimetry. The morphology and phase behaviour of the blends are sensibly influenced by the composition. X‐ray data support the existence of separated crystal phase of the two polymers only for HTH10 contents higher than 30 wt.‐%. An increase of the clearing temperature of the original blends is found with decreasing concentration of the mesomorphic polymer in the range 100 to 30 wt.‐%. On cooling from the isotropic melt, a single crystallization process is observed, whose temperature decreases with increasing amount of HTH10. A large depression of the melting temperature of PBT is found in the composition range 0 to 50 wt.‐% of HTH10. Blends quenched from the isotropic state exhibit one single glass transition temperature, intermediate between those of the starting polymers. The results suggest the occurrence of miscibility phenomena of PBT and HTH10 in the amorphouse phase.