| Popis: |
The intrinsic viscosities [η] and sedimentation constants S0 have been determined for poly-(4,4′-diphenylphthalein) terephthalamide (PPPTA) fractions in DMF, as well as in a binary θ-solvent (DMF:cryclohexanol=60:40 wt.%). Weight average molecular weights Mw were determined for the PPPTA by an equilibrium method, and by the Archibald method of non-stationary sedimentation equilibrium. The curvilinear character of logarithmic dependences of [η] on Mw for both solvents points to permeability of PPPTA macromolecules. This led to α use of the Yamakawa-Fujii theory in an analysis of the experimental data, and in the Gaussian region the following values were obtained in DMF: (h02/M)12=1·48×10−8cm, A=75 A, d=7·5A; in the θ-solvent: (h02/M)12=1·40×10−8cm, A=73A, d=7·3A; here h02 is the mean square end-to-end distance for the chain in the θ-solvent, A is the statistical Kuhn segment length, d-is the macromolecular diameter. The hindrance factor for rotation of poly-(4,4′-diphenylphtalein)terephthalamide δ=(h02/hf.r.2)12=1·10–1·15 (hf.r.2 being the macromolecular dimensions assuming there is free rotation about single bonds in the main chain). Thus poly-(4,4′-diphenylphthalein)terephthalamide is close to cellulose as regards chain rigidity. |
