A NEW SEMICRYSTALLINE, THERMOPLASTIC POLYIMIDE FOR CARBON-FIBER-REINFORCED COMPOSITES

A new semicrystalline polyimide (PI-2) has been prepared from 1,3-bis( 4-aminophenoxy)-2,2-dimethylpropane and 3,3',4,4'-benzophenonetetracar boxylic dianhydride. The polymer, which has a grass transition tempera ture of 230 degrees C and a melting point of 335 degrees C, displays o utstanding toughness with a fracture energy of 4.28 KJ/m(2). The tough ness may be associated with the polymer's unique morphology, which con sists of randomly stacked, ribbon-like lamellae. A reactive precursor approach has been used to prepare carbon-fiber reinforced composites t hat display interlaminar fracture energies (G,,) as high as 1.81 KJ/m( 2).