ABSTRACT:The cure of diglycidyl ether of bisphenol A (DGEBA) and a homologous series of poly(ethylene oxide) diglycidyl ether (PEODE) epoxy resins with 4,4Ј-diaminodiphenyl sulfone (DDS) was studied by scanning and isothermal differential scanning calorimetry (DSC). The heat of polymerization was relatively independent of monomer structure and chain length when determined by isothermal DSC. Variations in the heats of polymerization determined by the scanning method were attributed to degradative reactions at higher temperatures during the scan. The activation energies determined by scanning DSC experiments were relatively constant at 61 Ϯ 3 kJ/mol. However, using an isothermal cure method, the activation energies were found to vary with monomer structure and extent of cure. The isothermal kinetics were analyzed in terms of the autocatalytic model on the basis of competing reaction paths involving catalysis by either initial impurities or hydroxyl groups produced in situ. The activation energies of both reaction paths were found to vary with monomer structure and degree of conversion.
The cure of diglycidyl ether of bisphenol A (DGEBA) and a homologous series of poly(ethylene oxide) diglycidyl ether (PEODE) epoxy resins with 4,4Ј-diaminodiphenyl sulfone (DDS) was studied by scanning and isothermal differential scanning calorimetry (DSC). The heat of polymerization was relatively independent of monomer structure and chain length when determined by isothermal DSC. Variations in the heats of polymerization determined by the scanning method were attributed to degradative reactions at higher temperatures during the scan. The activation energies determined by scanning DSC experiments were relatively constant at 61 Ϯ 3 kJ/mol. However, using an isothermal cure method, the activation energies were found to vary with monomer structure and extent of cure. The isothermal kinetics were analyzed in terms of the autocatalytic model on the basis of competing reaction paths involving catalysis by either initial impurities or hydroxyl groups produced in situ. The activation energies of both reaction paths were found to vary with monomer structure and degree of conversion.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.