The quest for the valorization of technical lignins has been a keen interest for lignin chemists in the past 40 years. Owing to its multifunctionality, one of the promising strategies is to employ lignin as low-cost replacement of petro-based polyols in the production of polyurethanes. The structural heterogeneity and purity of technical lignins impeded effective incorporation of lignin in polymeric materials. Here, high-, medium- and low-molecular-weight fractions of an industrial softwood Kraft lignin preparation were prepared by sequential precipitation using a co-solvent system. A series of secondary polyols were applied in the lignin-polyurethane synthesis to improve lignin miscibility in the crosslinked network, and consequently enhanced the stiffness of the polymeric materials. In recent years, the development of lignocellulose biorefineries has provided new growth spots of technical lignins in addition to those generated as co-products in the pulp and paper industry. A hardwood solvolysis lignin was extracted by acidic aqueous tetrahydrofuran in a novel pretreatment called cosolvent enhanced lignocellulosic fractionation (CELF). Different formulations of polyurethanes synthesized with CELF lignin has been explored. The effects of lignin molecular characteristics and their intermolecular interactions with secondary polyols and isocyanates on mechanical and thermal properties of the lignin-based polyurethanes were investigated by tensile tests, DMA, SEM, and TGA.<br/>

Polyurethanes from unmodified technical lignin fractionated by sequential precipitation

2019 Fall National Meeting

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