Studies on the curing and thermal behaviour of diglycidyl ether of bisphenol-A (DGEBA) in the presence of aromatic diimide-diacids

This paper describes the synthesis and characterization of aromatic diimide-diacids (DIDAS) obtained by reacting pyromellitic dianhydride (PMDA), 4,4'-oxo diphthalic anhydride (ODA), 1,4,5,8-naphthalene tetra carboxylic dianhydride (NTDA) with excess of 4-aminobutyric acid (B) or 6-aminohexanoic acid (H) using N,N-dimethyl formamide (DMF) as solvent. The synthesized compounds were used as curing agents to investigate the effect of structure on the curing and thermal behaviour of diglycidyl ether of bisphenol-A (DGEBA). Structural characterization of DIDAS was done by using FTIR, H-1-NMR, C-13-NMR spectroscopy and elemental analysis. Curing behaviour of DGEBA in the presence of aromatic DIDAS was investigated by differential scanning calorimetry (DSC). The peak exotherm temperature (T (P)) was low in the case of DIDAS synthesized from ODA and high in the case of DIDAS synthesized from NTDA. Thermal stability of the isothermally cured DGEBA with DIDAS was investigated using dynamic thermogravimetry in nitrogen atmosphere. The char yield was highest for resin cured with DIDAS containing NTDA.