Hydrothermal Liquefaction of Kraft Lignin with Selective Alkylation of Phenolic Groups for Polyurethane Foam Production

摘要

Kraft lignin was efficiently liquefied in a PEG400-cthylene carbonate-water mixture solvent with K2C03 as the catalyst into bio-polyols for the preparation of bio-based polyurethane foams. The effects of process parameters including the proportion solvent, reaction temperature, liquefaction time, and lignin-solvent ratio on the properties of bio-polyols and bio-based polyurethane foams were investigated. Liquefaction conditions of 170 C, 30 min, 0.5% K2CO3 loading, and 10%-30% lignin loading were preferred for the production of bio-polyols with promising material properties. The phenolic groups of kraft lignin were alkylated to aliphatic hydroxyl groups after liquefaction and thereby enhanced the reactivity of lignin towards to isocyanates for polyurethane foam preparation. Bio-based polyurethane foams exhibit superior compressive property and thermal stability to a reference foam prepared from PEG400.