Exploring the reactivity of aliphatic and phenolic hydroxyl groups in lignin hydrogenolysis oil towards urethane bond formation

Lignin is the second most abundant natural polymer that exhibits a complex structure with various amounts of aliphatic and phenolic hydroxides. The use lignin as source polyol to make lignin-based polyurethanes (PUs) has been subject intense studies in recent years. It well known there difference reactivity between aromatic hydroxyl groups towards isocyanates. For simple model systems using conventional fossil-fuel based polyols overall kinetics are known. However, unveiling kinetic behavior obtained when combining an isocyanate derived components exhibiting different types challenging. Therefore, in-depth investigation compounds hydrogenolysis oil elucidate these differences presented will be invaluable development PUs. Understanding involved lead optimized synthetic protocols higher valorization potential for In this work, monolignol studied concerning their Isothermal experiments revealed rate constants reaction orders while non-isothermal DSC was used obtain activation energies through Friedman isoconversion model-free-kinetics (MFK) approach. These results were confirmed FT-IR 1H NMR. found all cases, hydroxide react fastest isocyanates slowest Reactions isocyanates, independent type, fall extremes shown by Apparent ranging from 55.2 kJ·mol-1 39.5 corresponding 5.19·10-3 M1?n s-1 1.04·10-3 s-1. work capstone further material renewable