RHEOLOGY OF POLYSULFONE

The viscosity‐shear rate functions for polysulfone (PSF) condensates ranging from 0.4RV to 0.95RV were determined using capillary rheometry, The most probable distribution of molecular weights of these resins allowed facile comparison with the polydisperse Bueche theory for viscosity, The agreement in shape of the viscosity function with theory was good but the data were displaced by a factor of 3 to 4 to higher reduced shear rate, a fairly common occurrence for melts. The high absolute value of PSF viscosity was explained with existing empirical correlations as a combination of low critical molecular weight and strong intermolecular interactions. The temperature dependence of viscosity was found to be close to that for polystyrene in the temperature range, Tg + 90 to Tg + 190°C. The die swell, end corrections, and melt fracture characteristics were also determined. The latter was found to occur at a constant wall shear stress of about 6 × 106 dynes/cm2 while the die swell and end corrections were found to be small. Copyright © 1978 Society of Plastics Engineers, Inc.