Effect of viscosity variation with temperature on the compounding behaviorof immiscible blends

Morphology development in the compounding of immiscible blends depends on a number of material properties and process conditions. In this work, differ ent model blend systems are considered to outline the effects of the relati ve transition temperatures and viscosities of the blend components. We focu s on the evolution of blend morphology, specifically phase continuity. A fr amework based on these factors is presented for analyzing the compounding b ehavior of immiscible blend systems. With the minor component at 10 wt%, it was found that phase inversion during compounding occurred in blends with a viscosity ratio of less than 0.2, independent of the relative transition temperatures. It was shown that in these constant mixer temperature runs, t he torque trace was not a completely reliable indicator of phase inversion. When a temperature ramping program was used, the lower melting point compo nent formed the continuous phase initially, independent of the viscosity ra tio. Quantitative measures of the amount of minor component which was conti nuous at different mixing times were made using selective extraction in a S oxhlet apparatus. Results from compounding runs of polycarbonate/polyethyle ne, an amorphous copolyester/polyethylene and polybutylene/polycaprolactone blends are presented.