Effect of UV radiation on photolysis of epoxy maleate of bisphenol A

The behavior of unsaturated polyesteric resin epoxy maleate of bisphenol A (EMBA) to UV was investigated using both infrared (IR) and optical microscopy (OM) techniques. The UV radiation produces important modifications of the EMBA sample. A photodegradation process takes place by a free radical mechanism and involves both photolysis and photodegradation reactions. In the early stage of photolysis, the excitation of the double bonds of EMBA sample takes place with formation of radicals. The radicals, by combination, form some cross-linked structures. These structures undergo secondary reactions with hydroperoxide formation. The splitting of the EMBA chains initiated by hydroperoxide compounds leads to new aromatic and etheric structures, with elimination of both CO and CO2.