Thermosets based on castor oil modified with Diels-Alder adduct of levopimaric acid and diglycidyl ether of bisphenol A. The kinetic analysis of the curing reactions and thermal behavior of the cured products

The thermosets were obtained using diglycidyl ether of bisphenol A as epoxy resin and castor oil modified with Diels-Alder adduct of levopimaric acid with maleic anhydride as hardener and reactive diluent. The kinetic parameters of the curing reaction were evaluated, using the variable peak exotherm methods of Ozawa, Kissinger and the “Thermokinetics-3” software (Netzsch). The thermal degradation of the cured product takes place in three or four steps, depending on the chemical structure of the crosslinking agents. The thermal lifetime was also calculated. FT-IR-MS analysis of the evolved gases has showed the presence of water, carbon dioxide, aliphatic and aromatic derivatives, anhydrides, acid, esters and at higher temperatures, compounds with abietane structure.