STUDIES ON BLENDS OF BINARY CRYSTALLINE POLYMERS - 1 - MISCIBILITY AND CRYSTALLIZATION BEHAVIOR IN POLY(BUTYLENE TEREPHTHALATE) POLYARYLATES BASED ON BISPHENOL-A ISOPHTHALATE

The miscibility and crystallization behavior of binary crystalline ble nds of poly(butylene terephthalate) [PBT] and polyarylate based on Bis phenol A isophthalate [PAr(I-100)] have been investigated using differ ential scanning calorimetry (DSC) and wide-angle X-ray diffraction (WA XD). Both polymers were able to crystallize over a wide range of blend composition and temperature. This blend system exhibited a single com position-dependent glass-transition temperature over the entire compos ition range and two distinctive melting peaks in some compositions. Th e equilibrium melting point depressions of both PET and PAr(I-100) wer e observed, and the Flory-Huggin's interaction parameter of chi(12(PBT )) = -1.3 was obtained. It indicated that these blends were thermodyna mically miscible in the melt. The crystallization rate of neat PAr(I-1 00) was very slow. However, it was much faster when the PET was added. The crystallization rate of PAr(I-100) was significantly influenced w hen the PET crystal was previously formed. It was not only due to the amorphous phase composition shifted to a richer PAr(I-100) content aft er the crystallization of PET but also to the constraint of the PET cr ystal phase. On the other hand, the crystallization rate of PET was re duced due to the addition of PAr(I-100).