POLACEK, Institute of Physical Chemistry, Czechoslovak Academy of Sciences, Prague, CzecFoslovakia It is necessary to stress that the initial concentrations (about 0.4 g./100 ml.) 469 During the study of molecular weight distributions in fresh, naturally, and artificially aged Svitprene K (polychloroprene polymerized in emulsion at 35☌.),4 the extrapolation of reduced specific viscosities to zero con- centration, according to Huggins' equation, was used for the determination of intrinsic viscosities of benzene solutions of the samples and their frac- tions, and on the experimental data obtained the precision of Hart's method was verified. An approximative value of is then calculated by using an average N curve the result is used to determine the proper N curve and in the same way the definite value of the intrinsic viscosity is calculated. For polymer-poor-solvent system, it is necessary to establish several N versus qsp curves covering the required range of in- trinsic viscosities. (1) the experimental values of qsp and C, and also the proper value of 21' taken from the graph. Intrinsic viscosity may then be calculated from one specific viscosity measurement by substituting in eq. This constant is, however, dependent on specific viscosity (polymer- good solvent system) or, moreover, on intrinsic viscosity (polymer-poor solvent ~ystem).~ Hart3 suggested therefore a graphic method for single- point determination of intrinsic viscosity based on the arranged equation of Schulz and Blaschke : For polymer-good solvent system, it is possible to establish a graph of N (reciprocal of k) versus specific viscosity. Using the equation of Schulz and Blaschke for single-point determination of intrinsic viscosity, it is necessary to know the value of constant k. For this reason, when smaller precision is sufficient, a quicker method of calculation of intrinsic vicosity from a single specific viscosity measurement is ad- vantageous. This procedure is precise but rather lengthy as specific viscosities have to be measured a t several concentrations. POLACEK, Institute of Physical Chemistry, Czechoslovak Academy of Sciences, Prague, CzecFoslovakia In the extrapolation procedure for the determination of intrinsic viscosity of polymer solutions, the equations of Huggins' or Schulz and Blaschke2 are usually used. XXXIX, PAGES 469-473 (1959) Single-Point Determination of Viscosity J. ISSN 0021-9606.JOURNAL OF POLYMER SCIENCE VOL. "Non‐Newtonian Viscosity of Solutions of Ellipsoidal Particles". Journal of the Physical Society of Japan. "The Effect of the Brownian Motion on the Viscosity of Solutions of Macromolecules, I. American Association for the Advancement of Science (AAAS). "Viscosity and the Shape of Protein Molecules". "The Influence of Brownian Movement on the Viscosity of Solutions". Series A, Containing Papers of a Mathematical and Physical Character. Proceedings of the Royal Society of London. "The motion of ellipsoidal particles immersed in a viscous fluid". A practical method for the determination of intrinsic viscosity is with a Ubbelohde viscometer. In polymer chemistry intrinsic viscosity is related to molar mass through the Mark–Houwink equation. More generally, intrinsic viscosity can be used to assay quaternary structure. ![]() For example, the intrinsic viscosity can provide rough estimates of the number of subunits in a protein fiber composed of a helical array of proteins such as tubulin. The intrinsic viscosity is very sensitive to the axial ratio of spheroids, especially of prolate spheroids. The intrinsic viscosity formula may also be generalized to include a frequency dependence.
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