Epoxidized linseed oils based networks. Case of thermal degradation

The thermal oxidation of networks based on epoxidized linseed oil cured with an anhydride hardener was studied in the 120-200 degrees C range by means of FTIR spectroscopy and gravimetry. Systems with 1-1 and 1-0.6 epoxy/anhydride stoichiometry were compared. The ageing tests monitored on thin films revealed that non-stoichiometric systems would be intrinsically more oxidizable than stoichiometric ones because of a higher concentration in reactive sites but stoichiometric system displays paradoxically higher levels of mass loss because those later originate from methyl cyclohexane hardener group. In the case of thick samples, the differences in oxygen diffusivity for both systems induce that oxidized layer would be slightly thicker in non-stoichiometric system than in stoichiometric ones would lead to lower in non-stoichiometric systems compared to stoichiometric ones. (C) 2019 Elsevier Ltd. All rights reserved.