UV-resistant transparent lignin-based polyurethane elastomer with repeatable processing performance

Lignin, as a green and environmentally sustainable natural material, is indispensable to be reasonably developed and utilized. Herein, lignin macromolecules are used as raw materials of polyhydroxyl structure to synthesize polyurethane macromolecules. It is found that the optimal mass ratio of lignin to isocyanate group in the synthesis of polyurethane is 95/5. The lignin-based polyurethane putted the lignin as a fulcrum to form a hydrogen bond with the polyurethane macromolecular chain to form a hydrogen bond network structure, so that its elastic recovery rate attains 94.7%. Meanwhile, its tensile strength and breaking elongation rate reach 16.2 MPa and 1049.5% respectively. Furthermore, the lignin-based polyurethane synthesized in this work still maintain excellent mechanical properties after thermal reprocessing. Moreover, the lignin-based polyurethanes prepared by this approach also possess excellent transparency and UV resistance, and the average ultraviolet protection factor (UPF)value of the lignin-based polyurethane hot-pressed fabrics obtained by hot pressing is greater than 50. This work provides an innovative and sustainable strategy for the further application of lignin, a pure natural material, as a bio-based multifunctional additive to packaging, textiles, automotive trim and other fields.