Novel Food Packaging Based on Naturally-Plasticized Poly (Lactic Acid) for Enhanced Nutritional Storage

Samar Fadl, M. & Tarek Madkour, M.^*

Department of Chemistry, The American University in Cairo, AUC Avenue, Egypt

Dr. Tarek Madkour, M., Department of Chemistry, The American University in Cairo, AUC Avenue, Egypt.

Keywords: Biodegradable; Environmentally Friendly; Poly (Lactic Acid); Natural Plasticizers; Food Packaging

Abstract

In order to contribute to sustainable development, alternatives to fuel-based polymers must be employed. Poly (lactic acid) (PLA) is a common natural polymer that is currently used in food packaging applications but with limited applicability due to its poor mechanical behavior (high elastic modulus and low elongation at break). To overcome PLA weaknesses and to enhance its flexibility and applicability in food packaging while preserving its environmentally friendly nature, three natural plasticizers, namely polyethylene glycol (PEG), tri n-butyl citrate (TBC), and triacetin (TA), are employed in this study. Stress-strain measurements showed that PEG did not enhance the mechanical response of PLA. Strangely, increasing PEG content has resulted in worsening the mechanical response of PLA, which was attributed to the formation of hydrogen bonding between PEG hydroxyl groups and PLA carbonyl oxygens, which limited the extensibility of the chains and increased its stiffness. Different concentrations of TBC and TA plasticizers were far more efficient when compared to PEG ones. The energy values of PLA/ TBC and PLA/TA samples have shown significant increase over PLA/PEG samples. Quite interestingly, stress relaxation of 10% PLA/TA samples showed an anomaly with upturn in the sample modulus at higher elongation values indicating an increased toughness of the samples with strain. This unique behavior was attributed to the formation of small crystallites resulting from the ordering of the polymeric chains at higher strain values as was confirmed by DSC measurements.

This is an open access article distributed under the Creative Commons Attribution License which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. (CC BY 4.0).