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)d iphenylsulfone]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), oly-[4,4 '-bis'(4''-N-phenoxy)diphenylpropane]imide of 1,3-bis'(3',4-dicarboxyp henoxy)benzene were studied by viscometry and exclusion liquid chromat ography. For both poly(amic acid)s the Kuhn segments are similar (appr oximately 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 segment al model of a chain molecule and the Yamakawa-Fujii model of rigid and or short chains that takes into account the draining effect, The obta ined data confirm that the rigidity of poly(ether imide) is higher tha n that of poly(amic acid).