Thermal oxidation of aromatic epoxy-diamine networks

The thermal oxidation of DGEBA-DDS (bisphenol A diglycidyl ether + 4,4'-diaminodiphenyl sulfone) and TGMDA-DDS (4,4'-methylenebis(N,N-diglycidylaniline) + 4,4'-diaminodiphenyl sulfone) was performed at 80, 120, and 200 degrees C and was monitored by FTIR Oxidation was shown to generate amides and carbonyls. Comparisons were done with model systems displaying some common reactive groups, which highlighted the predominating role of methylene in a position of ether in DGEBA-DDS and methylene in a position of nitrogen hold by TGMDA in TGMDA-DDS. The participation of CH2 in alpha position of DDS hardener group seems to depend on the temperature and decrease when lowering it. The oxidation of such complex systems must hence be described by a co-oxidation model where each kind of reactive sites is described by its own set of kinetic constants. (C) 2019 Elsevier Ltd. All rights reserved.