Yamila Victoria Vazquez

This study investigates the processability and performance limits of high-density polyethylene (HDPE) recovered from mixed polyolefin waste under realistic mechanical recycling conditions. The waste stream was processed by extrusion and injection molding, with parameters actively adapted. ATR-FTIR and DSC analysis confirmed HDPE as the matrix, contaminated with minor fractions of polypropylene (PP), PET, and polyurethane (PU). The reprocessed material exhibited a single melting peak at 132 °C and a melt flow rate (MFR) of 9.9 ± 0.6 g 10 min⁻¹, indicative of moderate degradation. Mechanical testing revealed reduced tensile strength and elongation at break compared to virgin HDPE, indicating compositional heterogeneity and poor interfacial adhesion. Field emission scanning electron microscopy (FESEM) revealed dispersed inclusions and microvoids acting as stress concentrators, consistent with reduced ductility. Crucially, progressive reduction of back pressure during processing optimization was essential for stabilizing melt flow and minimizing shear-induced degradation. This adjustment enabled consistent mold filling despite the material’s variability. The results demonstrate that mixed HDPE waste can be successfully valorized for non-structural applications such as plastic lumber or pallets, providing a sustainable pathway for recycling heterogeneous streams without costly pre-treatment or compatibilization.

The aim of this work is to analyze two different strategies based on industrial symbiosis (IS) approaches, for the combined valorization of plastic waste from rubber polymerization process (WSBR) and plastic from Waste Electrical and Electronic Equipment (WEEE). The proposed strategies are: (a) WSBR as compatibilizer for HIPS/ABS mixtures from WEEE; and (b) WSBR as a component in mixtures with plastics from WEEE (HIPS or ABS). In the first strategy, two different proportions of HIPS/ABS mixtures are studied using three different concentrations of WSBR onto each one. In the second one, mixtures of each plastic WEEE, ABS and HIPS, with two different amounts of WSBR are analyzed. Tensile strength and ductility of ABS with 20 wt% of WSBR, increased around 8% and 40% respectively, with respect to the ABS. Regarding tensile behavior of HIPS and HIPS with 20 wt% of WSBR, both matches up to the break of the last one at a strain of 1.5 %, approximately. Obtained results indicate that the second strategy, is the best one for the combined valorization of both plastic wastes. This conclusion is based on the fact that properties are not deteriorated in successive melt-mixing. It is completely aligned with IS approaches, combining two plastic waste, an industrial one (WSBR) and a postconsumer one (WEEE), for the obtention of new materials with appropriate properties for their use.

Current shampoo bottles are oversized, using more plastic than necessary. In order to promote plastic minimization, the aim of this work is to determine how much it is possible to reduce the thickness of current shampoo bottles while maintaining their functionality and performance. In this way, a quantification of the maximum plastic material reduction in the manufacturing of bottles of massively consumed shampoo was assessed. Mechanical testing simulations of shampoo bottles with different capacities and shapes were performed for top load and squeeze load efforts. For these simulations, three different thicknesses were considered: original, 30% reduced and the minimum admissible for being considered as rigid packaging. From the simulations, it was corroborated that shampoo bottles are oversized, allowing them to reduce their amount of plastic by at least 30%. Also, it was found that bottle shape is crucial to its mechanical performance, being the simplest bottle the most resistant, when bottles with the same capacity and thickness are compared. When less material is used, less is discarded, and, consequently, less is turned into waste. Then, rethinking current bottles following ecodesign criteria seems to be the way for an adequate sustainable approach compatible with green marketing strategies and plastic waste minimization.