(133d) Advancing Sustainable Cellulose-Based Packaging with Supercritical Impregnation Technology

Cellulose is the most abundant biopolymer in nature and constitutes roughly 50 wt% of lignocellulosic biomass. Advancing fabrication of cellulose-based materials with improved hydrophobicity and UV-resistance could improve its performance for packaging applications. Imparting desired properties into cellulosic substrates can be facilitated by integrating additives into cellulosic matrices. Modification of cellulosic substrates should be pursued through green methods and benign additives in order to limit negative impacts on the environment and human health. Supercritical fluid impregnation (SCI) is a green chemistry process that applies supercritical carbon dioxide (T_c = 31 ^°C, P_c = 73.8 bar) as a tunable solvent for plasticizing and modifying polymer substrates. SCI proceeds by dissolving additives into the bulk fluid phase and facilitating mass transfer of additives into polymer substrates. Thus, SCI could be leveraged to fabricate novel cellulose-based materials with improved surface properties.

The present study evaluates the supercritical impregnation (SCI) of bio-based additives into cellulose substrates. Cellulose substrates are modified with additives to improve hydrophobicity (e.g., ethyl oleate) and UV absorption capacity (e.g., vanillin). The influence of process conditions on the efficiency of SCI of bio-based additives into cellulose substrates is evaluated at varying temperatures (40 °C to 80 °C), pressures (80 bar to 120 bar), and processing times (0.5 h to 24 h). The influence of co-solvents to ease the swelling of cellulose substrates is evaluated through screening species with unique molecular structures and properties. The capacity of cellulose substrates to absorb additives is determined through gravimetric measurements, spectroscopic and microscopic characterizations. Performance capabilities of the modified cellulose substrates are interrogated through mechanical, thermal, and sorption analysis. Collectively, the findings of the present study advance insights on process-structure-performance relationships toward engineering sustainable, cellulosic packaging materials modified from agricultural resources using environmentally cogent, chemical processes.