Design of Experiments as a tool for post-consumer PLA packaging recycling: correlation between washing parameters and degradation

Abstract

Abstract The increasing demand for sustainable packaging solutions has led to the widespread adoption of biodegradable polymers such as polylactic acid (PLA) in the packaging industry. However, the efficient recycling of post-consumer PLA packaging remains a challenge due to contamination from residual food and other substances. This study presents the application of Design of Experiments (DoE) in the evaluation of washing parameters, typically used in the recycling industry, in the degradation of post-consumer biodegradable PLA packaging. A series of experiments were conducted using a factorial design to investigate the effect of key washing parameters, including NaOH concentration, washing temperature, washing time, and surfactant concentration, on the degradation of PLA. The degradation was accompanied by rheology employing the Cox-Merz rule, which establishes the relationship between complex viscosity and steady state viscosity. The results indicated that a washing process with lower degradation rates could be obtained by adjusting the washing parameters within specific ranges. The application of DoE allowed the identification of the most influential factors and their interactions in the degradation of PLA during the washing step. This study demonstrates that this is a valuable tool in the development of sustainable recycling processes for biodegradable packaging materials, contributing to a circular economy and reducing environmental impact.