MOLECULAR-PROPERTIES OF POLY(AMIC ACID)S AND POLY(ETHER IMIDE)S IN SOLUTIONS

The solutions of two poly(amic acid)s: poly-[4,4'-bis'(4''-N-phenoxy)diphenylsulfone]amic acid of 1,3-bis'(3',4-dicarboxyphenoxy)benzene and poly-[4,4'-bis'(4''-N-phenoxy)diphenylpropane]amic acid of 1,3-bis'(3',4-dicarboxyphenoxy)benzene as well as of poly(ether imide), poly-[4,4'-bis'(4''-N-phenoxy)diphenylpropane]imide of 1,3-bis'(3',4-dicarboxyphenoxy)benzene were studied by viscometry and exclusion liquid chromatography. For both poly(amic acid)s the Kuhn segments are similar (approximately 30 Angstrom, whereas for poly(ether imide) the Kuhn segment is somewhat larger (40 - 50 Angstrom) depending on the model used for calculation. The calculations were performed using both Kuhn's segmental model of a chain molecule and the Yamakawa-Fujii model of rigid and or short chains that takes into account the draining effect, The obtained data confirm that the rigidity of poly(ether imide) is higher than that of poly(amic acid).