Effect of structure of aromatic imide–amines on curing behavior and thermal stability of diglycidyl ether of bisphenol-A

The curing behavior of diglycidyl ether of bisphenol-A (DGEBA) with aromatic imide-amines having aryl ether, sulfone, and methylene linkages was studied using differential scanning calorimetry (DSC). Six imide- amines of varying structure were synthesized by reacting 1 mol of naphthalene 1,4,5,8-tetracarboxylic dianhydride (N) or 4,4 0 -oxodiphthalic anhydride (O) with excess (>2 mol) of 4,4 0 -diaminodiphenylether (E) or 4,4 0 -diaminodiphenyl methane (M) or 4,4 0 -diaminodiphenyl sulfone (S). The im- ide-amines prepared by reacting O or N with S, M, and E have been designated as OS/NS; OM/NM, and OE/NE, respectively. Structural characterization of imide-amines was done using FTIR, 1 H NMR, 13 C NMR, and elemental analysis. The curing behavior of DGEBA in the presence of stoichiometric amount of imide-amines was investigated by recording DSC scans. A broad exothermic transition was observed and the peak exotherm temperature was found to be dependent on the structure of imide-amines. The peak exotherm temperature (Tp) was lowest in case of imide-amines OE and highest in case of imide-amines NS/OS. Thermal stability of isothermally cured DGEBA in the presence of imide-amines was evaluated by dynamic thermogravimetry. The char yield was highest for resin cured with imide-amines NE. 2007 Wiley Periodicals, Inc. J Appl Polym Sci 107: 1946-1953, 2008