MISCIBLE POLYBENZIMIDAZOLE BLENDS WITH A BENZOPHENONE-BASED POLYIMIDE

Miscible blends of the aromatic polybenzimidazole, poly(2,2(m-phenylene)-5,5 prime -benzimidazole) (PBI), and the aromatic polyimide formed from 3,3 prime ,4,4 prime -benzophenone tetracarboxylic dianhydride and 3,3 prime -diaminobenzophenone (LaRC TPI) have been prepared. Blends with PBI were prepared in N,N-dimethylacetamide solution starting with either the polyamic acid or a 95% imidized form of LaRC TPI; the blend was then precipitated into water or cast as films. The mixture was then imidized thermally to obtain PBI/LaRC TPI blends. Evidence for miscibility was obtained. The IR spectra displayed shifts in the N-H stretching band, thereby providing evidence for specific interactions related to miscibility of these two polymers.