Synthesis of phenolic resol resins using cornstalk-derived bio-oil produced by direct liquefaction in hot-compressed phenol-water

For the synthesis of biomass-based resol resins, cornstalk powders were liquefied in a hot-compressed phenol-water (1:4, wL/wt.) medium at 300-350 degrees C. It was observed that essentially no phenol was reacted with the cornstalk degradation intermediates during the liquefaction process. The cornstalk-derived bio-oils contained oligomers of phenol and substituted phenols, originated primarily from the lignin component of the cornstalk feedstock. Using the cornstalk-derived bio-oils, resol resins were readily synthesized under the catalysis of sodium hydroxide. The biomass-derived resol resins were brown viscous liquids, possessing broad molecular weight distributions. in comparison with those of a conventional phenol resol resin, the properties of the bio-based resins were characterized by GPC, FTIR, DSC and TGA. The as-synthesized bio-oil resol resin exhibited typical properties of a thermosetting phenol-formaldehyde resin, e.g., exothermic curing temperatures at about 150-160 degrees C, and an acceptable residual carbon yield of ca 56% at 700 degrees C for the cured material. (C) 2009 The Korean Society of Industrial and Engineering Chemistry. Published by Elsevier B.V. All rights reserved.