A study on blends of liquid crystalline copolyesters with polycarbonate .2. Transesterification control

Abstract

The inhibited and catalyzed ester exchange (transesterification) during melt blending of poly(bisphenol-A carbonate) (PC) and liquid crystalline poly(oxybenzoate-co-ethylene terephthalate) (POB-PET 40/60; P46) was investigated with differential scanning calorimetry. It was found that the ester exchange between P46 and PC was effectively inhibited for a 20% P46 blend at 240 degrees C, as further confirmed by nuclear magnetic spectroscopy. When the blending temperature and P46 concentration increased, only the transesterification between the PET segment in P46 and PC took place under inhibition. The morphology of the blends was analyzed with scanning electron microscopy and displayed a disconnected interface between P46 and PC under inhibition. Conversely, the transesterification took place between the POB segment in P46 and PC when a catalyst was added. (C) 1996 John Wiley & Sons, Inc.