Reverse-engineering for improved end-of-life and circularity of PLA beverage cups

Abstract

Over two-thirds of the life-cycle greenhouse gas emissions of a disposable PLA beverage cup are attributed to the production of the granules. Hence, an effective material recycling in the end-of-life (EoL) phase is vital to preserve the embodied energy and emissions from PLA production. According to the current state of technology, this poses a process engineering challenge, as direct shredding leads to elongated, not particularly free-flowing flakes, making further processing significantly more difficult. To address this, a tempering step can be introduced, which loosens the molecular structure and induces an isotropic behavior in the PLA, resulting in free-flowing granules after shredding (Ginter, 2019). These granules can be efficiently processed into re-compounds, similar to new PLA material.Based on these findings, this paper presents a methodological reverse engineering approach to examine the manufacturing phase, in order to identify changes and characteristics and hence potentials for further improvement within EoL treatment. From these findings, approaches are derived which can be integrated into the process chain to improve circularity and reduce life-cycle gaps. The applicability of the methodological approach and its contribution to greater sustainability will be demonstrated using the example of PLA beverage cups, including the application of the life-cycle gap analysis (Dieterle & Ginter 2022).