Optimization of Washing Parameters to Minimize the Degradation of Poly(lactic acid) Using Design of Experiments: A Contribution to the Recycling Chain

Author(s)

Paiva, Robert ; Pereira-Filho, Edenir Rodrigues ; Wrona, Magdalena ; Cruz, Sandra A.

• Document type: Journal article
• Source: JOURNAL OF POLYMERS AND THE ENVIRONMENT; v. 32, n. 4, p. 8-pg., 2023-10-13.

Abstract

The increasing demand for sustainable packaging solutions has led to the widespread adoption of biodegradable polymers such as poly(lactic 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 PLA packaging. The experiments were conducted using a factorial design to investigate the effect of key washing parameters, including sodium hydroxide 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 levels could be obtained by adjusting the washing parameters. The surfactant concentration, whether isolated or in combination with variables such as time and temperature at their higher levels, resulted in a less damaging effect in terms of degradation. On the other hand, time has a great influence on the level of degradation in PLA. This variable is more detrimental when considered in conjunction with others, such as temperature and the concentration of sodium hydroxide. Thus, the application of DoE allowed the identification of the most influential factors and their interactions in the degradation of PLA during the washing step and may be adjusted according to the dirtiness of the precursor material. This study demonstrates that this is valuable in the development of sustainable recycling processes for packaging materials, contributing to a circular economy and reducing environmental impact. (AU)

• FAPESP's process: 21/08224-1 - Recycling of oil-based and biological polyesters for food contact: degradation, migration and determination of (non) intentionally added substances
• Grantee: Sandra Andrea Cruz
• Support Opportunities: Regular Research Grants