Interpolymer interaction of an aromatic polyamic acid and the corresponding polyimide with polybenzimidazole

The interaction of poly(4,4'-oxydiphenylene)pyromellitamic acid and the corresponding polyimide with poly(2,2'-(m-phenylene)oxy-5,5'-dibenzimidazole) in solution and in the solid state was studied within a wide range of temperatures (300-1073 K) and concentrations by viscometry, thermal-ionization mass spectrometry, themogravimetry, IR spectroscopy, and high-resolution 13 C NMR spectroscopy. The interaction between the polyamic acid and polybenzimidazole involves partial displacement of the solvent bound in complexes with polymers. The functional groups of the polyimide and polybenzimidazole are linked by hydrogen bonds. At temperatures above 723 K, a cross-linked structure is formed that yields, on further heating, a product with a high content of carbonized residue