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Dimensions, coils viscosity

The extrapolation to zero concentration is performed to eliminate the effects of molecular interferences likely to occur even in dilute solutions and obtain the influence of an isolated polymer coil on the viscosity of the solution. Only T and T <, have the dimensions of viscosity (Poise or Pa. s). Specific viscosity and relative viscosity are dimensionless. Intrinsic viscosity, reduced viscosity, and inherent viscosity all have the dimension of inverse concentration. The nomenclature of viscosity parameters is given in Table 7. [Pg.52]

Strauss and Williamst have studied coil dimensions of derivatives of poly(4-vinylpyridine) by light-scattering and viscosity measurements. The derivatives studied were poly(pyridinium) ions quaternized y% with n-dodecyl groups and (1 - y)% with ethyl groups. Experimental coil dimensions extrapolated to 0 conditions and expressed relative to the length of a freely rotating repeat unit are presented here for the molecules in two different environments ... [Pg.70]

According to the interpretation given above, the intrinsic viscosity is considered to be proportional to the ratio of the effective volume of the molecule in solution divided by its molecular weight. In particular (see Eq. 23), this effective volume is represented as being proportional to the cube of a linear dimension of the randomly coiled polymer chain,... [Pg.611]

Here c is the polymer concentration by weight. < the density of the polymer, a an effective bond length or measure of the coil dimensions, and to the monomeric friction factor. The subscript zero indicates the pure polymer. Since 2 (H), the mean-square end-to-end chain separation, the viscosity will be directly proportional to the polymer concentration unless the plasticizer modifies the coil swelling. At high molecular weight the monomeric friction factor is increased by the factor (MIMf)" and M, is increased relative to the undiluted polymer [equation (55)]. Thus... [Pg.101]

Coil dimensions Static light scattering, sedimentation measurements, small angle X-ray, solution viscosity... [Pg.74]

We have omitted a great deal of detail in this discussion of polymer viscosity. The interested reader will find some of the missing information supplied in Flory (1953). In particular, we have omitted all numerical coefficients, which limits us to ratios as far as computational capability is concerned. Numerical coefficients are available for Equation (92), for example, and this allows coil dimensions to be evaluated from viscosity measurements. A general conclusion that unifies all of this section is that any factor that causes a polymer chain to be more extended in space —whether by coil unfolding or swelling by solvent —tends to increase [77]. This is exactly what we expect in terms of the purely qualitative picture provided by Figure 4.8. Example 4.6 illustrates this for some actual polymers. [Pg.187]

Fundamental theories of transport properties for systems of finite concentration are still rather tentative (24). The difficulties are accentuated by the still uncertain effects of concentration on equilibrium properties such as coil dimensions and the distribution of molecular centers. Such problems are by no means limited to polymer solutions however. Even for the supposedly simpler case of hard sphere suspensions the theories of concentration dependence for the viscosity are far from settled (119,120). [Pg.40]

This work examines the effect of long-chain branching on the low-shear concentrated solution viscosity of polybutadienes over a broad range of molecular weights and polydispersity. It will show that the reduction in molecular coil dimension arising from long-chain branching is more sensitively measured in concentrated than in dilute solutions for the polymers examined. [Pg.92]

For a given polymer-solvent system, the intrinsic viscosity varies with the molecular weight of the polymer. According to Flory, the intrinsic viscosity is directly proportional to the hydrodynamic volume occupied by the random coil of the polymer molecule in a solution. In addition, the hydrodynamic volume is related to the cube of the typical linear dimension of the random coil (root mean square end-to-end distance). The intrinsic viscosity is expressed as ... [Pg.426]

B 17 Bxjeche, A. M. Dimensions of coiling polymer molecules from viscosity and light scattering. J. Am. Chem. Soc. 71, 1452 (1949). [Pg.97]

The hydrodynamic properties of solutions of native double-stranded DNA have thus far eluded complete quantitative interpretation, in spite of very extensive investigation. A synthesis of experimental data has recently been furnished by Doty [84 ) some of the earlier experimental results may be found in the papers of Doty, Bunce-McGiix, and Rice (86) Doty, Makmur, Eignek, and Schildkraut (55) and Kawade and Watanabe (135 ). It is easy to see that the double helices are not perfectly inflexible, for the observed intrinsic viscosities are far lower than those of rigid rods or ellipsoids with the Watson-Crick dimensions, p = Af/4600. On the other hand, the customary flexible-coil treatments also do not apply to these data. For example, if the correlation plot of against g (a) M l [) ], / is attempted, it is found that... [Pg.274]

Closely connected with the conformational dimensions of the polymer coil, and therefore with the limiting viscosity number, are some other macroscopic quantities, viz. the limiting sedimentation coefficient and the limiting diffusivity. [Pg.280]

In the preliminary report, we have shown that the enhancement effect of the salts cannot be ascribed to their effect on the coil dimension of PVP. Intrinsic viscosity of PVP in aqueous solutions considerably decreased in the presence of 2 M CsCl. In the presence of 80 kg m" dextran, however, the coil dimension of PVP was decreased so much as not to be further influenced by the addition of CsCl. [Pg.341]


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See also in sourсe #XX -- [ Pg.364 ]




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Viscosity, dimensions

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