Epoxy Thermosetting Systems: Dynamic Mechanical Analysis of the Reactions of Aromatic Diamines with the Diglycidyl Ether of Bisphenol A.

Dynamic mechanical behavior during the reactions of four aromatic diamines m-phenylenediamine, 4,4-diaminodiphenylmethane, 4,4-diaminodiphenyl sulfone, and benzidine with the diglycidyl ether of bisphenol A was studied by torsional braid analysis under isothermal conditions. Depending on the cure temperature, three types of behavior were observed I below Tgg the glass transition temperature of the reactive systems at the gel point II between Tgg and Tg infinity the glass transition temperature of the ultimately cured polymers III above Tg infinity. Overall acrivation energies and apparent overall rate constants of the cure reactions based on third-order overall kinetics were determined before gelation, after gelation but before vitrification, and after vitrification. The influence of cure temperature and structure of the diamines on the kinetic parameters is discussed. Author Modified Abstract