High‐temperature resins based on aromatic amine‐terminated bisaspartimides

Various 4,4′‐bis{N2‐[4‐(4‐aminophenoxy)phenyl]aspartimido}diphenylmethane (APADM)‐type precursors were synthesized by Michael‐type reaction of an aromatic bismaleimide (1mol) with an aromatic diamine (2 mol) in an aprotic solvent. The structures of these materials were characterized by using Fourier‐transform infrared (FT‐IR), 1H nuclear magnetic resonance (NMR) and 13C‐NMR; their curing behaviors and thermal stabilities were evaluated by differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA). The thermal polymerization of APADM by heating it above its melting temperature produced a tough polymer. From these preimidized precursors, graphite‐fiber laminates were prepared and their mechanical properties evaluated. To elucidate the thermal curing mechanism and the structure of the polymer, a model compound, N‐[4‐(4′‐aminobenzyl) phenyl] aspartimidobenzene was synthesized. The gas‐chromatographic mass spectra of these compounds has suggested a mechanism for their decomposition. The structure of the polymer also was studied by using FT‐IR and 1H‐NMR.