Abstract
Effect of pH on the gelation of phenol-modified melamine resin was investigated, focusing on the rate of gelation, the morphology of gelled resin, and the flexural strength of cured resin. It is confirmed that pH of varnishes influences the rate of gelation and also the temperature dependence of flexural strength. It is found that gelled resins have different sea-and-island structures depending on the pH of varnishes. The resins gelled under acid conditions have a melamine sea structure while the ones under alkaline conditions have phenol sea structure.
