PREPARATION AND PROPERTIES OF PHENOLATED WOOD/PHENOL/FORMALDEHYDE COCONDENSED RESIN

A phenolated wood/phenol/formaldehyde cocondensed novolac-type resin was prepared with a two-stage procedure. Wood was first liquefied in the presence of phenol by using an acid catalyst to produce a phenolated wood, and after the liquefaction, formalin (i.e., formaldehyde aqueous solution) was added to conduct a cocondensation reaction for converting the remaining nonreacted phenol into resin components. It was found that this procedure can convert almost all the phenol remained after liquefaction into resin, and therefore significantly upgrades the practical value of the liquefaction technique. In addition, it can also greatly improve the thermofluidities of the phenolated wood resins and the mechanical properties of their molded products. As a result, the flow temperatures and melt viscosities of the cocondensed resins were much lower than those of the phenolated wood resins. However, these two properties were more or less similar to those of the conventional novolac resin, resulting in an excellent processability. The flexural properties of the molded products made from the cocondensed resins were much higher than those of the phenolated wood and also somewhat superior to those of the conventional novolac resin. Therefore, this preparation procedure is a prospective technique for preparing wood-based novolac resins. (C) 1995 John Wiley & Sons, Inc.