Self-Organization Initiated by Shear Flow of Mixtures of Polymer Melts

Abstract

Structure formation during deformation of a mixture of melts of a thermoplastic polymer (polysulfone) and a liquid crystal polymer has been investigated by means of analytical scanning electron microscopy. Viscosity of the LC polymer at high shear rate has been significantly lower in comparison with the thermoplastic. The experiment has been performed at controlled volume flow under conditions of flow through a capillary at a high and low deformation rate. The principal result of the observations has been the statement of self-organization effect manifested as the phase separation and formation of the regions with the increased concentration of the LC polymer in the thermoplastic matrix. Such system has been an emulsion, and a conical converging flow has been formed at the transition from the wide cylinder of the capillary viscometer to a narrow capillary installed at its bottom. Such geometry of deformation has led to the appearance of a longitudinal flow with the formation of jets (fibers) in the extrudate bulk and the surface layer of the liquid crystal polymer. Effective viscosity of the mixture has been lowered in comparison with this of the thermoplastic, due to self-assembly of the LC polymer.