Lignin-based polyurethane film reinforced with cellulose nanocrystals

Novel nanocomposite films were synthesized using cellulose nanocrystals (CNC) as a reactive reinforcing filler and lignin-based polyurethane (L-PU) as the matrix through a casting and evaporating method. A series of L-PU films were prepared by replacing polyol with lignin from 10 to 50% (molar percentage). The L-PU film with maximum addition of lignin content was used as the matrix, which were reinforced with 0.5, 1 and 5 wt% dosage of CNC. The structural, mechanical and thermal properties of the resulting films were evaluated by attenuated total reflectance-Fourier transform infrared spectroscopy (ATR-FTIR), X-ray diffraction (XRD), scanning electron microscopy (SEM), tensile test and thermal gravimetric analysis. The mechanical measurement showed that the tensile strength of the L-PU films was significantly improved by the addition of CNC as reinforcement. Thermal gravimetric analysis results demonstrated that the thermal stability of the L-PU film after the addition of CNC was slightly increased.