Lignin, a cross-linked aromatic heteropolymer found in the plant cell wall, together with cellulose and hemicellulose, plays a crucial role in the structural integrity of the plant. Around 70 million tons of lignin, a byproduct of the paper and pulp industry, is burned every year as a low value fuel. Significant attention has been given to a wide-scale use of lignin-derived products for various applications. The complex structure of lignin gives to this plant-derived polymer the potential to act as an antioxidant and inhibit radical oxidation reactions. Moreover, lignin possesses chromophoric groups, which can absorb UV-light. These properties render lignin promising for the application in food packaging. It can protect food from auto-oxidation and UV-degradation processes, thus extending its shelf life.<br/>In this research work, we incorporated lignin into another sustainable and biodegradable polymer, poly(lactic acid) (PLA). PLA is derived from starch and provides an excellent alternative to conventional petroleum-based plastics. However, antioxidant and UV-barrier activities remain a challenge for PLA products, limiting their application in food packaging. By incorporating lignin into PLA films, we were able to overcome these limitations without significantly compromising the mechanical properties. In order to optimize the effects of lignin on the films properties, lignin nanoparticles (LNPs) with high surface-to-volume ratio were prepared. Excellent dispersion of the LNPs was obtained by grafting some PLA chains from their surface, developing films with outstanding antioxidant and UV-barrier activity. These results pointed out the potential of such sustainable films for the application in food packaging.

PLA-lignin films for sustainable food packaging

ACS Spring 2022

The official archive and repository for all ACS Meetings & Expositions abstracts and select posters or presentations.