AbstractThe photooxidation in the solar UV range of tridimensional networks based on the diglycidyl ether of bisphenol A (DGEBA) and diaminodiphenyl methane (DDM) is characterized by the formation of carbonyl, amide, and hydroperoxide groups and by at least two types of chromophores. One absorbs strongly in the near UV, violet, and blue regions, and is responsible for the development of an internal screening effect leading to a decrease of photooxidation rate during exposure. The other, which absorbs in the red region (γmax= 615 nm), is responsible for the green color of oxidized smaples and is derived from the oxidation of the diamine bridge. The influences of hardener concentration and thermal treatments are explained in terms of a stabilizing effect of unreacted DDM molecules and a photoinitiating effect of some thermal‐oxidation products, presumably hydroperoxid
展开▼
