Effect of impurity content on long term performance of recycled HDPE for structural application

Thermoplastic wastes are some of the major components of global municipal solid waste (MSW), especially because of the large volume and low cost of these materials. Since the plastic wastes may be obtained from several sources, they might have been exposed to different storage and processing conditions and may exhibit different behavior depending on the degradation level. The impurity removal is critical and has significant effect in durability of the final product. In that context, the incorporation of waste in materials for structural application demands a series of technical evaluation procedures that need to be assessed, especially when the materials undergo constant pressure. This work aims to characterize blends with polypropylene (PP), which is commonly found in recycled high density polyethylene (HDPE) and to evaluate the effect of its content in both short-term mechanical behavior and stress cracking, comparing these properties to the ones of pristine HDPE. The study was carried out by means of tensile and impact tests, melt flow index (MFI), and Un-notched Constant Ligament Stress Crack Test (UCLS).