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Transport Phenomena in Thermal Engineering. Volume 2

ISBN:
1-56700-015-0 (Print)

A STUDY OF SHORT DIE SWELL BEHAVIOUR OF POLYMER MELTS IN EXTRUSION

J.Z. Liang
Department of Chemical Machinery, South China University of Technology, Guangzhou 510641, CHINA

Abstract

The rheological properties of rubber unvulcanized compounds have been investigated by using a Monsanto processability tester(MPT) and a set of capillary dies. It was found that the die-swell ratio(B) increased with increasing shear rate and the diameter ratio of the reservoir to the die( Dp/D) at the test temperatures. A mathematical model for describing the polymer melt die-swell in short die extrusion is presented in this paper, B = (1 + 2KSr + 2/3K2S2r)1/4 where ? is the entry convergence flow parameter and Sr is the recoverable shear strain. Better agreement is show between prediction and measurement for experiments on the sample and data reported in references.