SHEAR INFLUENCES ON THE SOLUBILITY OF LDPE IN ETHENE

The influence of shear on the demixing pressures of the binary system ethene/polyethene was determined viscometrically in the temperature ra nge 147-195 degrees C up to pressures of 1400 bar at polymer concentra tions of 18.4, 22.5 and 27.4 wt%, respectively. Autoclaves were used t o prepare the solutions and to measure cloud points for the stagnant s ystem. A high-pressure viscometer was used to perform experiments at s hear rates gamma up to 1500 s(-1). Under all conditions investigated h ere the two-phase area grows as gamma becomes larger and the demixing pressures increase up to 23 bar. This observation is in contrast to th eoretical expectation according to which it should be the one-phase re gion which expands under the prevailing conditions. (C) 1998 Elsevier Science B.V. All rights reserved.