Liquefaction of alder wood as the source of renewable and sustainable polyols for preparation of polyurethane resins

摘要

Liquefaction of wood-based biomass gives different polyol properties depending on the reagents used. In this article, alder wood sawdust was liquefied with glycerol and poly(ethylene glycol) solvents. Liquefaction reactions were carried out at temperatures of 120, 150 and 170 degrees C. The obtained bio-polyols were analyzed in order to establish the process efficiency, hydroxyl number, acid value, viscosity and structural characteristics using Fourier transform infrared (FTIR), carbon (C-13) and proton (H-1) NMR analyses. The results indicate that the optimal conditions for the liquefaction process are at 150 degrees C for 6 h. The results of the FTIR spectra analysis and the hydroxyl number in the range of 214-687 mg KOH/g showed that the obtained bio-polyols are a potential substitute for petrochemical polyols commonly used for the synthesis of polyurethane polymers. Polyurethane resins containing 90 wt% of bio-polyol were obtained by a one-step method using a hydraulic press. The material was pressed for 15 min (5 MPa) at 100 degrees C with an NCO/OH ratio in the range of 0.9-1.2. Dynamic mechanical thermal analysis (DMA) showed high cross-linking density and modulus of elasticity in a wide range of 62-1362 MPa.