Polyethylene Degradation Monitoring during the Multiple Melt Processing

In this paper, two rheological methods was used to evaluate the polyethylene degradation behavior. For this purpose, two linear low density polyethylene were subjected to multiple extrusion processes for 9 times. The melt flow index (MFI) results suggest that the viscosity of LL22501 and LL209 decreases and increases, respectively. In other words, during multiple melt processing, degradation have proceeded from the chain scission and crosslinking (or chain branching) path, respectively. However, the rheometry results indicate that the degradation in both samples have proceeded from crosslinking or chain branching path. The accuracy of the rheometry method is higher than the MFI test. In addition, the MFI test only provides data for a single point, while rheometry test provides a spectrum of rheological data. It can be concluded that the rheometry results are more reliable than the MFI results for the evaluation of the polyethylene degradation.