BLEND MORPHOLOGY DEVELOPMENT DURING MELT FLOW - CORRELATION OF A MODEL CONCEPT BASED ON DYNAMIC PHASE VOLUME WITH PRACTICAL OBSERVATIONS

An approach is first developed that can be used to identify the global morphology of an immiscible two-phase polymer-polymer blend under she ar flow. The basis for the modeling is the concept of a dynamic phase volume; this is based on relative abilities of the respective phases t o flow when under stress, and determined by the actual phase volume fr action and the viscosity ratio between phases. One result of the model ing is a schematic diagram providing guidelines for morphology develop ment during melt processing in a nonuniform stress field. Bisphenol A polycarbonate(PC)/ ABS blends were studied as an immiscible system, us ing variations of component ratio and viscosity ratio at constant comp osition. Blend morphology was characterized by scanning electron micro scopy and solid-state dynamic mechanical spectroscopy. Model predictio ns correlate well with experimental observations of the frozen-in soli d-state morphology following injection molding. Discussion also cover the utility of the model for blend design and limitations of the model ing approach. (C) 1999 John Wiley & Sons, Inc.