Synthesis and properties of polyimides fibers derived from 1,2,6-bis(p-aminophenyl)benzo1,2-d;5,4-d'biszimidazole

摘要

2,6-(4,4'-Diaminodiphenyl)benzo[1,2-d:5,4-d']biszimidazole was synthesized by condensation of 1,2,4,5-benzenetetramine tetrahydrochloride and p-aminobenzoic acid in polyphosphoric acid (PPA). Polyimide with benzobiszimidazole unit was prepared from the 2,6-(4,4'-diaminodiphenyl)benzo[1,2-d:5,4-d']biszimidazole and 4,4'-oxydiphthalic dianhydride in PPA. The polyimide was characterized by FT-IR, elemental analysis and wide-angle X-ray diffraction. The thermal properties of the polyimide were investigated by thermogravimetry(TG). It was found that the decomposition temperature for 5% weight loss occurred above 550 °C in nitrogen atmospheres. The crystalline solutions of liquid polyimide in PPA were spun into fibers using dry-jet wet spinning. The morphology of the fibers was observed by SEM and the tensile strength of fibers was tested. The diameters of the Fibers were about 50 μm and the tensile strengths were as high as 2.2 GPa. The polyimide fibers show outstanding mechanical properties and thermal stability.