Abstract
Synthesis of diglycidyl 2, 6-naphthalenedicarboxylate (DE) from 2, 6-naphthalene-dicarboxylic acid, its curing with several curing agents, and properties of the cured products are described. Synthesis of DE was carried out by the reaction of 2, 6-naphthalene-dicarboxylic dichloride with glycidol (90% yield, m.p. 143-144°C). DE was mixed with one of the curing agents (0.6-1.6 equivalents), and the mixture was heated at a temperature above the melting point of DE (150-220°C) to give the corresponding cured products. The products cured with trimellitic anhydride (TMA) or diaminodiphenylmethane (DDM) as a curing agent had good toughness and Tgs. To estimate the effect of introducing naphthalene moiety into epoxy resins, the properties of the cured products from DE were compared under the same conditions with those from diglycidylterephthalate (TE) and from diglycidylether of bisphenol A (DGEBA). The glass transition temperature (Tg) of the cured products of DE/DDM system was 200°C, showing 20°C higher than that of TE/DDM or DGEBA/DDM. Further, Tg of DE/TMA was 214°C showing 10°C higher than that of TE/TMA or DGEBA/TMA. In summary, the cured products from DE were superior to those from DGEBA in the properties such as flexural strength, flexural modulus, and water absorption.
