Abstract
Polyamido acids derived from 4,4 '-bis(4-aminophenoxy)diphenyl (diamine) and 1,3-bis(3 ',4-dicarboxyphenoxy)benzene dianhydride were synthesized in two amide solvents: dimethylformamide and N-methylpyrrolidone. Fibers with different extrusion ratios were obtained by the coagulation method. These fibers were converted to polyimide fibers by heat treatment. The influence of the solvent used in the polyamido acid synthesis and of the extrusion ratio on the structure and properties of polyimide fibers was examined. An increase in the extrusion ratio from 1 to 2 leads to an increase in the strength and elongation at break of the polyimide fibers.