EFFECT OF DYNAMIC CROSS-LINKING ON RHEOLOGICAL PROPERTIES OF MOLTEN POLYPROPYLENE ETHYLENE-PROPYLENE ELASTOMER BLENDS

Dynamic mechanical properties of uncrosslinked and dynamically crossli nked polypropylene/ethylene-propylene elastomer blends in the melt wer e compared. It was found that the dependence of dynamic viscosity and storage modulus on frequency reflects the type of phase structure of u ncrosslinked blends. Dynamically crosslinked blends with higher conten ts of elastomer shaw rheological properties which are typical of syste ms where the physical network of dispersed particles exists. Rheologic al properties of dynamically crosslinked blends at low frequencies and low shear rates were explained as a consequence of long-lived entangl ements among touching crosslinked elastomer particles. (C) 1997 Elsevi er Science Ltd.