Dilute solution viscosity applications

The dilute solution viscosity measurement is applicable to all polymers that dissolve to give stable solutions at temperatures close to the boiling point of the solvent. 

Applications and Limitations of Dilute Solution Viscosity Measurements... 

Harding, Stephen E. 1997b. The Viscosity Intrinsic of Biological Macromolecules. Progress in Measurement, Interpretation and Application to Structure in Dilute Solution. Progress in Biophysical Molecules Biological 68, 207-262. 

Taking into account the relevance of the range of semi-dilute solutions (in which intermolecular interactions and entanglements are of increasing importance) for industrial applications, a more detailed picture of the interrelationships between the solution structure and the rheological properties of these solutions was needed. The nature of entanglements at concentrations above the critical value c leads to the viscoelastic properties observable in shear flow experiments. The viscous part of the flow behaviour of a polymer in solution is usually represented by the zero-shear viscosity, rj0, which depends on the con-... 

Hydrodynamic properties, such as the translational diffusion coefficient, or the shear viscosity, are very useful in the conformational study of chain molecules, and are routinely employed to characterize different types of polymers [15,20, 21]. One can consider the translational friction coefficient, fi, related to a transport property, the translational diffusion coefficient, D, through the Einstein equation, applicable for infinitely dilute solutions ... 

The dominating working mode of polymer HPLC is the straight elution of small volume of sample solution along the column. There were attempts to introduce the differential and vacancy procedures in SEC. In both cases, the eluent was a diluted solution of the polymer while either a proper sample or a reference polymer [314] or even pure eluent [315] was injected. A broader application of these proposals was hindered by both the high eluent viscosity and the large sample consumption. Moreover, the dependences of log M vs. Vr (Equation 16.12) obtained by the conventional and the differential/vacancy methods are mutually shifted. The deviation between both dependences was attributed to the nonequilibrium situation in the vacancy polymer HPLC [316],... 

The model parameters q and ML can be estimated from experimental data for radius of gyration, intrinsic viscosity, sedimentation coefficient, diffusion coefficient and so on in dilute solutions. The typical methods are expounded in several recent articles and books [20-22], Here we refer only to the results of the application to representative liquid-crystalline polymers (See Table 1). 

Viscosity determinations at the highest convenient concentration are of practical value, because in most of the applications of nitrocellulose, solutions of these concentrations are used, and there is usually little difference between the concentration in use and that used for the determination. All nitrocellulose solutions that are not very dilute show more or less abnormal viscosity, i.e. the rate of flow is not proportional to the applied stress or pressure. The ease of flow of a solution at one degree of stress cannot then be inferred from a viscosity determined at another. Nevertheless the measured viscosity of a comparatively concentrated solution is in general useful information. This advantage is sacrificed in what is the most rational of all viscosity systems, the German I.G. Method. Measurements are made in dilute solutions and the results are expressed in terms of the Eigenviscositat (k) of Fikentscher and Mark [99] a function which to a large extent is independent of concentration ... 

Numerous empirical equations have been proposed to express the vis cosities as a function of concentrations for the determination of intrinsic viscosity. These equations have been tabulated in several textbooks (see, for example, Philippoff, 1942), but many of them have only limited applications and are already obsolete. Here we will only mention three commonly used ones. For dilute solutions the well-known Huggins equation (1942) can be written as... 

Another issue was the applicability of this approach to characterize the dilute-solution properties of associating polymers. Reduced viscosity is a linear function of the polymer concentration at low concentrations for the systems in this study, so the use of a Huggins-type relationship is justified. 

It is important to note that the typical application of xanthan uses a semi-dilute, not dilute solution. Interactions between the chains, which are not considered in this study, play an important role in the viscosity of these solutions. 

The basic resins need some form of modification to achieve (1) suitable application viscosities, (2) flexibility, and (3) reduction in costs if possible. Suitable polyamide resins (those of the more flexible variety) are thus frequently modified by the addition of EVA copolymer (high-viscosity, high-melt-point grade). The amount of EVA that can be added is restricted to a maximum of 25% in most cases because of compatibility problems. The blend is then further modified with selected tackifying resin addition and small quantities of filler, to reach an optimum balance of performance properties. To achieve maximum adhesion, it is common for polyamide hot melts of this type to be used in conjunction with a polyamide resin solution primer system for edging material. The primer is invariably a dilute solution of the base polyamide resin. 

Feakins D, Waghome WE, Lawrence KG (1986) The viscosity and structure of solutions. Part 1. a new theory of the Jones-Dole B-coefficient and the related activation parameters application to aqueous solutions. J Chem Soc Faraday Trans 82 563-568 Frank HS, Evans MW (1945) Free volume and entropy in condensed systems. III. entropy in binary liquid mixtures partial molal entropy in dilute solutions structure and thermodynamics in aqueous electrolytes. J Chem Phys 13 507-532... 

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