# Sustainable Upgrade of Post-Consumer PLA: The Effect of Adding a Plasticizer and a Chain Extender on the Functional Properties and Toxicity of This Recycled Bioplastic

## TL;DR

This study explores how adding plasticizers and chain extenders to recycled polylactic acid (PLA) affects its properties and safety for food packaging.

## Contribution

The study identifies contrasting roles of plasticizers and chain extenders in improving rPLA's properties while maintaining safety.

## Key findings

- Adding a plasticizer increased flexibility but raised migration values, potentially affecting safety.
- Chain extenders improved stability and reduced migration risk in recycled PLA.
- Only composites with high plasticizer content showed slight toxicity in intestinal cells.

## Abstract

The environmental risks associated with the use of petroleum-based
plastics are well known, and therefore, the use of biopolymers has
boomed in recent years. Polylactic acid (PLA) stands out as a great
alternative, and although PLA is compostable, its recycling is considered
a sustainable approach to manage its residues and promote a circular
economy. The aim of this work was to investigate the final properties
of post-consumer recycled PLA (rPLA) after the addition of different
additives. Post-consumer PLA-based plastics were obtained after a
simulation of service life and recycling processes of commercial PLA-based
water bottles, and subsequently, different composites including a
plasticizer and a chain extender (CE) were obtained by melt extrusion.
Significant changes were observed in the structural and thermal parameters
of the composites, including their crystallinity, when these additives
were incorporated. However, the water vapor permeability values were
not significantly different from that of control rPLA. In terms of
overall migration, the values obtained for samples containing CE were
well below the established limit, although samples containing plasticizers
showed quite high values. Cytotoxicity assays in intestinal cells
indicated that only composites with the highest plasticizer content
exhibited slight toxicity at the intestinal barrier. Overall, contrasting
roles were identified for the two additives: the plasticizer enhanced
the flexibility but led to increased migration values, whereas the
CE improved stability and reduced the migration risk. These results
demonstrated that modifying post-consumer rPLA with suitable additives
can improve its physical properties while maintaining safety, thus
offering a practical and sustainable approach to its use in food packaging
applications.