SYNOPSIS
Crosslinking by etherification of a large excess of bisepoxide with divalent metal salts of p-aminobenzoic acid was investigated. Mg and Ca were selected as the divalent metal salts, and bisphenol A diglycidyl ether was the bisepoxide used. In the crosslinking reactions, the metal salts exhibited catalytic activity for the etherification, with the Ca salt showing higher catalytic activity than the Mg salt. Hence, the etherification proceeded via an ionic mechanism in which carboxylate anion is concerned. The orders of reaction with respect to carboxylate anion concentration were one order for the both systems. The overall activation energies of the crosslinking reaction were 13.4 kcal/mol for the system containing Mg and 23.0 kcal/mol for the system containing Ca. The metal-containing cured resins obtained showed higher flexural strength, Rockwell hardness, and compressive strength than the resins without metal. Heat distortion temperature and glass transition temperature determined by dynamic mechanical properties increased with an increase in the metal salt content in the feed. Thermal decomposition was accelerated by the incorporated metal. In addition, the metal-containing cured resins have high boiling water and water resistances.