| Abstract: | The factors affecting pressure losses during extrusion of polymer melts are discussed in the present article. The rheological properties of an unvulcanized rubber compound were examined by using a Monsanto processability tester (MPT) under experimental conditions of temperatures varied 90 to 120°C and shear rates from 102 to 103 s?1. Furthermore, a set of dies with different entry angle (2α) was selected to identify the effects of die angles on pressure losses in capillary extrusion of the sample fluid. It was found that the total pressure drop (ΔP) decreased when 2α < 75 degrees, and then increased with increasing 2α. The ΔP reached the minimum value when 2α is around 75°. It suggests that the natural converging angle of the sample fluid be about 75° under the experimental conditions, according to the research results presented in previous work. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 80: 1150–1154, 2001 |
