Willow Lignin Recovered from Hot-Water Extraction for the Production of Hydrogels and Thermoplastic Blends

A blend of commercial willow cultivars (Salix spp.) was subjected to hydrothermal pretreatment: hot-water extraction in a pilot plant 65-ft³ digester. Lignin recovered from the autohydrolyzate (willow lignin, WL) was used to produce hydrogels and thermoplastic blends. Lignin-kaolin-acrylamide (WL 10.7 % w/w) and lignin-poly(ethylene)glycol diglycidyl ether (WL 66.7 % w/w) hydrogels exhibited favorable adsorption and absorption properties, respectively. Dye adsorption kinetics, swelling capacities, fragrance emanation, and compression moduli were measured for the hydrogels, along with SEM characterization. Additionally, WL was esterified by acetylation (C₂ , WAc) and acylation with lauroyl chloride (C₁₂ , WFAE and WFAE_H ). The crude and esterified lignin samples were blended (1-12 % w/w) with polylactic acid (PLA) via lab-scale melt extrusion to produce thermoplastic blends. The physicochemical properties of the blends were evaluated. They exhibited an increase in degradation temperature and UV absorbance with potential to hinder photodegradation of PLA and may be leveraged in packaging applications.