The use of rheological behavior to monitor the processing and service life properties of recycled polypropylene

Publication date: March 2019Source: Food Packaging and Shelf Life, Volume 19Author(s): C. Spicker, N. Rudolph, I. Kühnert, C. AumnateAbstractThe influence of multiple reprocessing cycles on the rheological, thermal and mechanical properties of pre-consumer polypropylene (PP) waste (or manufacturing scrap) was investigated. An increase in the melt flow rate (MFR) and a decrease in the viscosity and the mass average molecular weight were found as well as a narrowing of the molecular weight distribution. As a typical industry practice, manufacturing scrap is often mixed with virgin material. Thus, production material with 70% regrind was also examined. The measured properties followed the same trends as for reprocessing without refreshing. A separate investigation of thermal and thermal oxidative degradation showed a constant MFR at processing temperatures for thermally degraded material and a significant increase for thermal oxidative tests. The results provide a better understanding of the degradation mechanisms of PP and show that the rheological behaviors, MFR and melt viscosity, are well suited to assess these effects.Graphical abstract

Source: Food Packaging and Shelf Life - January 12, 2019 Category: Food Science Source Type: research