Effect of wall slip an rheotens mastercurves for linear PE melts

For two linear polyethylene melts, a HDPE and a LLDPE, Rheotens experiments at constant extrusion pressure and different extusion temperatures are rep orted. While at sufficiently small extrusion pressure Rheotens mastercurves were found, various deviations from the mastercurves were observed at high er extrusion pressures. By use of capillary rheometry and Mooney's method, these deviations could be attributed to a stick-slip transition in the extr usion die, and, in the case of LLDPE, to partial wall slip below the stick- slip transition.