PHYSICAL-PROPERTIES OF MOLDINGS FROM LIQUEFIED WOOD RESINS

The liquefied wood resins obtained by liquefying wood in the presence of phenol using phosphoric acid as a catalyst were applied to prepare the moldings by using hexamine as a hardener. The effects of the molding conditions and the moldings' compositions on flexural properties and water-sorption kinetics of the moldings were investigated. It was found that the liquefied wood resins had satisfactory and almost uniform curing reactivity, although they were composed of different kinds of wood components. The flexural properties of the liquefied wood moldings were enhanced with an increase in the amount of combined phenol within the liquefied wood and became comparable to those of the commercial novolak when the amounts of combined phenol were larger than 75%. Furthermore, it was also found that with an increase in the content of wood fillers the flexural properties of the liquefied wood moldings were enhanced more effectively than were the cases of the commercial novolak moldings, exhibiting that the liquefied wood resins could gain a greater reinforced effect from compounding with the wood fillers than did the commercial novolak resins, and the greater the amount of combined phenol, the higher the reinforcing performance of wood fillers. In addition, water-sorption measurements and the SEM observations of the moldings indicated that the liquefied wood resins had much greater hydrophilicity than that of the novolak and revealed a greater compatibility with wood fillers. (C) 1995 John Wiley & Sons, Inc.