Phosphorus-containing epoxy resins: Thermal characterization

Three novel aromatic phosphorylated diamines, i.e., bis N,N'-[3-[(3-amino-phenyl)methyl hosphinoyl] phenyl} pyromellitamic acid (AP), 4,4'-oxo bis N,N'-[3-[(3aminophenyl)methyl phosphinoyl] phenyl}phthalamic acid (AB) and 4,4'-hexafluoroisopropylidene-bis N,N'-[3-[(3-aminophenyl)methyl phosphinoyl] phenyl}phthalamic acid AF) were synthesized and characterized. These amines were prepared by solution condensation reaction of bis(3-aminophenyl)methyl phosphine oxide (BA-P) with 1,2,4,5-benzenetetracarboxylic acid anhydride (P)/3,3',4,4'-benzophenonetetracarboxylic acid dianhydride (B)/4,4'-(hexafluoroisopropylidene)diphthalic acid anhydride (F), respectively. The structural characterization of amines was done by elemental analysis, DSC, TGA, H-1-NMR, C-13-NMR and FTIR. Amine equivalent weight was determined by the acetylation method. Curing of DGEBA in the presence of phosphorylated amines was studied by DSC and curing exotherm was in the temperature range of 195-267degreesC, whereas with conventional amine 4,4'-diamino diphenyl sulphone (D) a broad exotherm in temperature range of 180 -310degreesC was observed. Curing of DGEBA with a mixture of phosphorylated amines and D, resulted in a decrease in characteristic curing temperatures. The effect of phosphorus content on the char residue and thermal stability of epoxy resin cured isothermally in the presence of these amines was evaluated in nitrogen atmosphere. Char residue increased significantly with an increase in the phosphorus content of epoxy network. (C) 2002 Wiley Periodicals, Inc.