Enhanced barrier properties of biodegradable PBAT/acetylated lignin films

Biodegradable materials are increasingly essential in modern society due to their environmentally friendly characteristics. Although poly(butylene adipate-co-terephthalate) (PBAT) has been evaluated as a suitable material for packaging and mulching, its high production cost and decrease in physical properties due to UV irradiation hinder its industrial application. In this study, lignin was used as an eco-friendly additive to address these issues, and acetylation was attempted to prevent the decrease in film properties caused by the self-aggregation of lignin. Through a simple acetylation process, lignin was 80.3% modified, as confirmed by FTIR and 31P NMR analysis. The resulting acetylated lignin showed excellent dispersibility and compatibility in the PBAT matrix, maintaining the composite film's mechanical and thermal properties even at 10% lignin content. The addition of acetylated lignin provided UV-blocking performance and thus strongly prevented the photodegradation of PBAT. Furthermore, the addition of acetylated lignin hindered the movement of infiltrated molecules within the composite, enhancing the oxygen and moisture barrier properties. As a result, the food packaging performance of PBAT/acetylated lignin films was enhanced. The use of PBAT/acetylated lignin composites is expected to provide a effective way of using lignin as a biodegradable polymer for industrial applications and a solution to overcome the disadvantages of existing PBAT-based biodegradable plastics.