Influence of the MWD of Poly(Vinylidene Fluoride) on its Viscoelastic Behavior in the Melt, Part I: Empirical Relationships

Abstract A deep analysis of the viscoelastic behavior of molten polyvinylidene fluoride (PVDF) was performed in oscillatory shear flow and using isothermal melt spinning. Owing to a thorough analysis of the molecular weight distribution of various samples, empirical relationships relating the observed behavior and parameters of the MWD were obtained. These relations make use of simple and easy-to-handle rheological characteristics such as the crossover frequency and crossover modulus, Newtonian viscosity and relaxation time in shear, and factors such as the melt strength or breaking stretch ratio in extension. For this reason, these relationships may be of interest from an industrial point of view as an aid for tailoring materials or for the design and choice of processing techniques.