Influence of Processing Conditions on Productivity, Thermal and Rheological Properties of Reprocessed Low Density Polyethylene

Abstract

Abstract The market for recycled thermoplastic polymers is undergoing a sharp increase, although recyclate polymers are regarded as materials with inferior properties when compared to the virgin material. This study investigates the behavior of non-contaminated scraps of low density polyethylene (LDPE) from the plastic packaging industry after single processing stage, in terms of the productivity and the thermal and rheological properties. The LDPE used was reprocessed on a single-screw extruder (Miotto) of 90 mm screw diameter and L/D = 25. Three screw speeds (80, 90 and 100 min−1) were investigated at three processing temperatures (200, 250 and 300°C). The reprocessed materials were characterized by thermogravimetric analysis TGA, parallel plates rheometry and productivity. The results obtained by TGA showed a typical range of polyolefin degradation (350 to 450°C). The viscoelastic properties did not show significant changes in relation to the rheological behavior. Increasing the temperature and screw speed promoted a productivity gain of approximately 30%. This suggests that under the conditions studied it is possible to reprocess this material with good productivity ensuring its thermal, mechanical and rheological properties.