Dynamic viscoelastic properties of incompatible polymer blends

Abstract

Dynamic viscoelastic properties of phase‐separated polypropylene (PP)/styrene‐acrylonitrile copolymer (SAN), PP/ethylene–propylene–rubber (EPR), and nylon6 (PA)/SAN blends prepared by melt blending were measured in molten state. As characteristic to heterogeneous liquids, slow relaxation mechanisms due to domain structures of sizes ≂0.1–20 μm were found for dynamic moduli of three blends. These moduli were compared with predictions of an emulsion model of Palierne developed for concentrated emulsions. The emulsion model with parameters determined for the components extracted from the blends quantitatively described the properties of the blends. This result suggested that the slow relaxation mechanisms of incompatible polymer blends were attributed to recovery of domain shape and different in nature from those of polymeric systems being filled with inorganic solids and/or cross‐linked rubber particles.