Liquefaction of wood in the presence of phenol using sodium hydroxide as a catalyst and some of its characterizations

The extent of dissolution of wood in phenol was lower in the presence of water compared to those of aqueous alkali. The amounts of residue, combined phenol, and nonreacted phenol, as well as weight loss in liquefied mixture due to release of gaseous substances, changed widely with the change in composition of wood:phenol as well as with the concentration of alkali. In the presence of alkali, pH changed roughly four to five units during liquefaction reaction, while without alkali the change in pH was only about 2.0 to 2.5. The resulting pH was always acidic whether the starting pH was alkaline or acidic (e.g., noncatalytic system). However, after the liquefaction reactions, there was a large amount of uncombined phenol which could be removed by distillation method to a large extent. The molecular weight and melt-flow properties of the wood-based phenolated resins, as well as flexural mechanical properties of wood flour-filled molded materials, were evaluated. All these properties vary with the variation of liquefaction conditions of wood in phenol. Generally, wood-based phenolated resins with higher amount of combined phenol were lower in both molecular weight and melt-flow properties, but were higher in mechanical properties.