Alteration in Rheological Properties of Polyethylene by Extrusion Processing

Abstract

The effect of processing temperature in a single-screw extruder on molecular characteristics of polyethylene (PE) was studied by employing additive-free low-density polyethylene (LDPE) and linear low-density polyethylene (LLDPE) for extrusion coating. It was indicated that melt elasticity is enhanced by applied extrusion processing at high temperature, suggesting that long-chain branches are generated by cross-linking reaction. On the contrary, thermal analyses revealed that there is no change in the distribution of short-chain branches by extrusion processing. Further, chain scission of PE took place predominantly above 320°C. Meanwhile at low temperature, the processing history decreased the melt elasticity. This is attributed to shear modification phenomenon.