Abstract

The curing processes and thermal properties of resol-type phenol-urea-formaldehyde cocondensed resins, which were prepared by alkaline treatments of the cocondensed resins once synthesized from UF-concentrate and phenol, were investigated by torsional braid analysis. The resol-type cocondensed resins displayed almost the same curing behaviors and heat-resistance as a commercial resol. Their apparent activation energies determined by measuring temperature dependence of gel time were almost identical with that of resol, and quite different from that of UF resin. Their plywood adhesive performances were evaluated with a cyclic 4-hour boil test and a 72 hour boil test. The plywood test results passed the requirements for the JAS special grade structural plywood

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