Non-Newtonian Flow of Structured Systems. XI. Polymer Melts

Abstract
The possibility of applying a generalized flow model to polymer melts (polystyrene, polyisobutylene, butadiene-styrene copolymer) is shown and the presence of different flow regimes is demonstrated. Flow regimes are at separate shear rate ranges: Newtonian flow at low shear rates, pseudoplastic flow at medium shear rates and spurt of flow at high shear rates. Ways of constructing a generalized model of flow curve in reduced coordinates and obtaining time-temperature superposition are proposed. Approximate form of generalized flow equation is used. Temperature dependence of coefficients of the generalized flow equation is determined. The value of aggregation coefficient does not depend on the temperature. Viscosity coefficient of Casson is decreases with temperature growth. Compactness coefficient increases in accordance with Arrhenius equation.

Keywords: polymer melts, non-Newtonian flow, structural rheological model, temperature dependence of coefficients