Influence of molecular weight distribution on the melt extrusion of high density polyethylene (HDPE): Effects of melt relaxation behavior on morphology and orientation in HDPE extruded tubular films
- 1 November 1996
- journal article
- Published by Society of Rheology in Journal of Rheology
- Vol. 40 (6) , 1079-1093
- https://doi.org/10.1122/1.550801
Abstract
The influence of molecular weight distribution and extrusion processing variables on the morphological features and orientation of high density polyethylene (HDPE) uniaxially extruded tubular films was investigated. In order to gain a better understanding of the orientation–crystallization behavior occurring during extrusion processing, the melt flow properties of the two HDPE resins with identical M̄n (14 600) values but different molecular weight distributions (M̄w/M̄n=10.3, 15.1), utilized in our previous study, were characterized by dynamic rheological experiments over the temperature range from 150 °C to 230 °C within the angular frequency range from 0.1 to 100 rad/s. The experimental data were shifted to produce master flow curves. The flow activation energy calculated from the shifting process was found to be 25.9 kJ/mol for resin 1 and 29.1 kJ/mol for resin 2. The characteristic relaxation time at 190 °C obtained by use of a Carreau–Yasuda analysis for resin 2 having the broader molecular weight d...Keywords
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