Measurement of the pressure dependence of viscosity of polymer melts using a back pressure‐regulated capillary rheometer

Abstract

Abstract The effect of pressure on the melt viscosity was experimentally investigated for five polymers: polycarbonate (PC), acrylonitrile‐butadiene‐styrene (ABS), polystyrene (PS), polypropylene (PP), and low‐density polyethylene (LDPE). Measurements were carried out using capillary rheometer modified to allow regulation of back pressure. To enable correction for the entrance pressure drop, two round‐hole dies were used: a 1‐mm diameter die of length 10 mm and an orifice die of the same diameter. For determining the pressure coefficient from the experimental viscosity data, time‐pressure superposition was applied to generate a master curve to which the Carreau‐Yasuda model was fitted. The resulting pressure coefficients revealed that for the polymers studied the order of the degree of the pressure dependence is as follows: PS > ABS > PC > PP > LDPE. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010