Cellulose Nanocrystal‐Reinforced Polyurethane Foams From Sawdust Liquefaction Using Crude Glycerol and Polyethylene Glycol

ABSTRACT Rigid polyurethane (PU) nanocomposite foams were prepared from a sawdust‐derived polyol obtained by liquefaction with crude glycerol (CG) and polyethylene glycol (PEG) and reinforced with cellulose nanocrystals (CNCs) at 0, 1, 3, and 5 wt% relative to polyol mass. CNC morphology was examined by atomic force microscopy (AFM), while foam morphology, chemical structure, thermal stability, density, compressive strength, and thermal conductivity were evaluated by scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FTIR), thermogravimetric analysis (TGA), density measurements, compression testing, and thermal conductivity analysis. Increasing CNC content decreased the average cell diameter from 170 to 80 μm. Foam density increased from 0.071 to 0.093 g cm −3 , while compressive strength enhanced from 0.275 to 0.410 MPa. The density‐normalized compressive strength promoted from 3.87 to 4.41 MPa (g cm −3 ) −1 , indicating that the mechanical improvement was not attributable to density alone. In addition, the degradation temperature increased and thermal conductivity decreased from 0.034 to 0.022 W m −1 K −1 . The FTIR spectra confirmed the successful formation of urethane linkages during the polymerization process. The results demonstrated the potential of CNCs to improve the performance of bio‐based polyurethane foams containing sawdust‐derived polyols.