MORPHOLOGY AND RHEOLOGY OF POLYSULFONE VECTRA-A950 BLENDS

Blends of polysulfone (PSu) with a liquid crystalline copolyester (Vec tra-A950; VA) have been prepared by melt mixing. Their morphology has been studied by scanning electron microscopy (SEM). Either blend speci mens as obtained from the melt mixing or fibers drawn from the melt we re used for the SEM analysis. Further information on the morphology of the blends was gained by extraction of the PSu phase with methylene c hloride. Preliminary theological characterization of the blends was ma de by measuring the viscosity curves at 290 and 300 degrees C, with a capillary viscometer having a die of 1 mm diameter and L/D = 40. Final ly, an attempt at improving the phase compatibility was made by synthe sizing a copolyester, having the same structure of commercial VA, in t he presence of preformed PSu and using the product as a possible compa tibilizer. It was demonstrated that the blends are composed of two imm iscible phases showing poor adhesion. The LCP droplets could, neverthe less, be deformed into oriented fibrils under elongational flow condit ions. The LCP particles were shown to coalesce into large domains, and to migrate toward the outer layer of, e.g., extruded rods, under the influence of appropriate flow conditions, thus showing that there is a strong mutual influence between morphology and theology of these mate rials. (C) 1995 John Wiley and Sons, Inc.