Design and manufacturing diversity undermine circularity: The case of a simple yogurt cup

Abstract

Recycling initiatives target increased recycling rates and closing packaging loops, yet practical, political, and industrial challenges may remain unnoticed. This study delves into the mechanical, processing, and morphological disparities within a polypropylene (PP) polymer stream, especially for yogurt cups. The waste source (mixed MSW or plastic collection) does not considerably impact mechanical properties. However, analyzing PP packaging diversity raises doubts about achieving high-quality recyclate. Categorization attempts include thermoforming, injection molding, and copolymers. An idealized stream of yogurt cups reveals complexities due to various decoration technologies and processing methods. Within a closed-loop system for yogurt cups, thermoforming and injection molding are crucial, prompting the imitation of virgin and post-consumer cup materials. A threshold value of 70 wt.% and deterioration effects are identified alongside common fillers and polymers. As high-quality regranulate becomes increasingly essential, we must also consider the effects of processing methods and aim for a clean, homogeneous stream.