Performance Evaluation of Vegetable Oils as Novel Bio-Based Plasticizers in Polylactic Acid Films Meant for Food Packaging Applications

Abstract

Polylactic acid (PLA) has garnered considerable attention as a food packaging material due to its biodegradable nature and significant potential as a sustainable alternative to petroleum-based plastics. However, its inherent brittleness and limited flexibility pose challenges to its widespread adoption. In the current study, vegetable oils were incorporated into PLA films as bio-plasticizers to reduce brittleness and improve flexibility. The PLA (5% (w/v) in chloroform) films were prepared using the solvent casting method. Sunflower oil, virgin coconut oil, and castor oil were used as bioplasticizers at 0.05% (v/v) in the PLA film-forming solution, and PLA films without plasticizers and films containing glycerol, a conventional plasticizer, were used for comparison. The unplasticized PLA film exhibited brittle behaviour, with low elongation at break (EB) values of 1.17 ± 0.06% in the machine direction (MD) and 1.10 ± 0.10% in the cross direction (CD). Incorporation of virgin coconut oil (VCO) resulted in a 213% increase, or approximately a 3.13-fold increase, in the %EB of PLA films. The Melting Enthalpy (ΔHm) for native PLA films was 23.875 J/g, which increased in PLA film samples incorporated with vegetable oils. There was a significant increase in ΔHm of film samples plasticized with castor oil (PLA-CO), indicating a wellpacked crystalline structure and improved thermal stability. These findings highlight the potential of vegetable oils as sustainable plasticizers for PLA films, offering tailored improvements in flexibility and thermal stability. The study supports the development of eco-friendly packaging solutions, reducing reliance on conventional plasticizers with proven health risks.