Abstract
Naphthalene based epoxy resins were synthesized from dihydroxynaphthalenes, and the relation between the strucrure and properties of their cured products with phenol novolac was studied.
The measurements of fracture toughness of the cured products showed that the epoxy resin prepared from 2, 6-dihydroxynaphthalene had high fracture toughness of 1.2 MPa·m1/2. 2, 6-isomer gave small storage modulus below Tg in dynamic mechanical analysis, which depends on the increase of free volume fraction caused by the restriction of packing of molecular chains under the influence of stiff backbone, i.e. 2, 6-naphthalene structure. The increased toughness of 2, 6-isomer seems due to the increase of plastic deformation at crack-tip because of its large free volume fraction.
