Biobased ternary composites for food packaging: influence of natural plasticizers and starch on polylactic acid performance

Polylactic acid (PLA) is a biodegradable thermoplastic that has emerged as a suitable replacement of petroleum-derived polymers commonly used in packaging. In this study, it has been demonstrated that glyceryl tributyrate (TB) and triethyl citrate (TEC), non-toxic, environmentally friendly additives, can be effectively employed as natural, renewable, and sustainable plasticizers to improve PLA’s thermal and physical properties, thus expanding its potential applications. The study initially investigates the impact of varying contents of these two natural plasticizers on PLA properties, identifying the optimal plasticizer percentage based on improvements in PLA performance. PLA/Starch composites were then formulated using the selected percentage of TB or TEC as plasticizers. The study further analyzes the relationship between sample morphology and their thermal and mechanical properties, as well as functional properties relevant to food packaging, such as transparency, water vapor permeation, and migration. PLA-TEC/Starch films exhibited the highest crystallinity and best barrier properties, which was attributed to the different affinities between starch and the plasticizers. Furthermore, the samples were transparent in the visible region of the spectrum but exhibited negligible transmittance in the UV-C region as well as a decrease of migration in isooctane. Therefore, these biodegradable and eco-friendly films show great potential as viable alternatives to traditional packaging materials, particularly for fatty and UV-sensitive foods.

Graphical abstract