Dilute solutions high-viscosity solvents

True solvents dissolve the polymer at all concentrations. Some liquids give solutions at certain concentrations, but further dilution precipitates the polymer. In these quasi-solutions, polymer molecules collect in clusters, raising the effective molecular weight of the polymer and giving an abnormally high viscosity. Solvents in the middle 80 per cent of the polymer s parameter range are... 

As far as elastic effects are concerned, Eqs. (14.9.27) and (14.9.28) state that A, is proportional to and N2 equals zero. Both of these relations are found to be true for dilute polymer solutions in high-viscosity solvents [38]. Typical data for N are shown in Figure 14.21. 

Solutions of linear high polymers show unusually high viscosity even at very low concentrations. In fact, the discovery of polymer molecules was due to the high viscosity (7). We expect that at infinite dilution increase in the viscosity coefficient of solution over that of the pure solvent is characteristic of a polymer molecule. Thus, we define a quantity called intrinsic viscosity by ... 

Comments (S42, S75).- Sera of plasmacytoma patients and newborn show differences of over 100% compared to the wet chemistry method. Due to their high viscosity, these samples must be diluted in a ratio of 1 15. If water or common salt solution are used as solvents, bilirubin concentrations occur that are 1 to 3 times higher. It is therefore recommended to dilute with a serum having a very low bilirubin concentration. This method, however, is very questionable and should therefore be rejected. Heparin is mentioned as an anticoagulant EDTA is unsuitable for plasma separation. 

Similar solution behavior was reported(9-11) for sulfonate ionomers. Rochas eit al. (9) observed a polyelectrolyte effect for acrylonitrile-methallylsulfonate copolymers in DMF. Lundberg and Phillips(10) studied the effect of solvents, with dielectric constants ranging from c 2.2 to e 46.7, on the dilute solution viscosity of the sulfonic acid and Na-salt derivatives of sul-fonated polystyrene (SPS). For highly polar solvents such as DMF and dlmethylsulfoxide (DMSO, e 46.7) they observed a polyelectrolyte effect, but for relatively non-polar solvents such as THF and dioxane (c = 2.2) no polyelectrolyte effect was observed. Like Schade and Gartner, these authors concluded that polar solvents favor ionization of the metal sulfonate group while non-polar solvents favor ion-pair interactions. 

In many operations the material to be purified is received as a liquid or in solution and is processed as is. Modification may be needed as with a high viscosity liquid that may require dilution with a miscible solvent. 

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