Biodegradable composites of modified holocellulose, poly(butylene adipate-co-terephthalate), and polylactic acid: Preparation and properties

Holocellulose was extracted from corn cobs by a deep eutectic solvent and modified by various carboxylic acids. The resulting holocellulose esters were further blended with poly(butylene adipate-co-terephthalate) (PBAT) and polylactic acid (PLA) by using a solvent casting method to prepare holocellulose ester/PBAT/PLA composites. The mechanical properties of the composites were affected by the length of the ester side chain of the modified holocellulose. The addition of lauric acid-modified holocellulose, i.e., holocellulose laurate (HCL), effectively improved the compatibility between the components in the composite, and the composite with 4 wt% HCL showed good comprehensive properties. Compared with PBAT/PLA, HCL/PBAT/PLA composite had better mechanical properties, water stability and gas barrier stability, and similar thermal stability. The elongation at break increased by 41.0 %, while the water absorption capacity, water vapor permeability and oxygen permeability decreased significantly. The HCL/PBAT/PLA composite also demonstrated good reprocessability and simulated transport properties. There were no significant changes in the mechanical properties and structure after five cycles of reprocessing and simulated transport, and the mechanical property retention rates were 93.7 % and 95.2 %, respectively. The results showed that modified holocellulose can be used as a toughening agent and filler, which can expand the application of lignocellulose in the field of biodegradable packaging materials.