FLOW BEHAVIOR OF HIGH-IMPACT POLYSTYRENE/POLYPROPYLENE BLENDS

Effects of composition and incorporated compatibilizers on theological properties of high-impact polystyrene/poIypropylene blends were investigated. Three Linear styrene-butadiene block copolymers were used as compatibilizers. Rheological characteristics of the blends were obtained by dynamic measurements using rotational rheometer and by measurements of steady shear flow in capillary. Viscoelastic properties seem to be more sensitive to the blend composition than to the structure of compatibilizers. Viscosity of the blends is a non-linear function of composition. Verification of empirical rules interrelating linear and non-linear viscoelastic functions showed that the Cox-Merz rule fails with the studied systems. Better agreement was found between the values of the first normal stress coefficient calculated by a new empirical rule using dynamic data and those obtained by the Gleissle calculation method from capillary data.