Recyclability by extrusion molding of high-density polyethylene from plastic bags

High-density polyethylene (HDPE) is one of the main materials used in the world, applied in the most varied human activities. Because of its extreme resistance, it take years to degrade in nature, causing buildup of large volumes of material in landfills, when it does not end up in aquatic habitats due to the lack of awareness by society. Therefore, the recycling of this material is important. In this context, the present study describes the recycling of HDPE from plastic bags with four extrusion cycles in a twin-screw extruder. Changes in physical, chemical, thermal, and mechanical properties with reprocessing cycles were investigated by Fourier-transform infrared spectroscopy (FT-IR), X-ray diffraction (XRD), thermogravimetry/derivative thermogravimetry analysis (TG/DTG), differential scanning calorimetry (DSC) and tensile and flexion testing, as well as by determination of density and melt-flow index (MFI). The results indicated that post-consumer HDPE from plastic bags can be reused without affecting the mechanical properties for at least four processing cycles, enabling use in various products with satisfactory mechanical performance.