Viscosity solvent solution

PPS is well-recognized for its exceptional chemical resistance. There are no known solvents for PPS below 200°C. A comprehensive survey of solvents for PPS has been published (115). Extreme conditions are required to dissolve PPS in both common and exotic solvents. Solution viscosity measurements are made difficult by this high temperature requirement. Inherent viscosity measurements are performed in 1-chloronaphthalene at 206°C at a concentration of 0.4 g of polymer per deciliter of solution. The inherent viscosity of PPS solutions shows a usefiil response to increa sing molecular weight. Table 2 shows a correlation of inherent viscosity measurements with melt flow measurements. 

Thermal Properties. The thermal stabiUty of cellulose esters is deterrnined by heating a known amount of ester in a test tube at a specific temperature a specified length of time, after which the sample is dissolved in a given amount of solvent and its intrinsic viscosity and solution color are deterrnined. Solution color is deterrnined spectroscopically and is compared to platinum—cobalt standards. Differential thermal analysis (dta) has also been reported as a method for determining the relative heat stabiUty of cellulose esters (127). 

Viscosity. Solvent viscosity of resins is influenced by the concentration of resin, the softening point, the molecular weight distribution, the chemical composition of the resin, and the type of solvent. The higher the resin concentration, the higher the viscosity. For a given concentration, solution viscosity depends on the softening point of the resin (Fig. 22). 

In reversed-phase TLC, mobile phases with high eontent of water do not wet alkyl-bonded siliea layers unless partially modified silica plates are used. It is well known that high-viscosity solvents do not generate the same plate number as low-viscosity solvents because of the solute diffusion coefficient and slow mass transfer [21]. 

Zafarani-Moattar, M.T. and Shekaari, H. Volumetric and speed of sound of ionic liquid, l-butyl-3-methylimidazolium hexafluorophosphate with acetonitrile and methanol at T = (298.15 to 318.15) K, /. Chem., Eng. Data, 50,1694,2005. Wang, J. et al.. Excess molar volumes and excess logarithm viscosities for binary mixtures of the ionic liquid l-butyl-3-methylimidazolium hexafluorophosphate with some organic solvents, /. Solution Chem., 34, 585, 2005. 

Gamma radiation can be used with macroscopic amounts of polymer. This is particularly welcome when polymers are not compatible with the GPC technique. Larger samples can be characterized by viscosity changes, usually measured in dilute solutions. All that is needed is a suitable solvent. If the Mark-Houwink parameters are known, it is possible to calculate viscosity-average molecular weight, Mv, from dilute solution viscosities. However, even the raw viscosity-concentration data in terms of the reduced viscosity may be enough to indicate the sensitivity of a given polymer in qualitative terms. The reduced viscosity at concentrations c is isp/c where t]sp — (solution viscosity — solvent viscosity)/solvent viscosity. 

The ease with which wax may be removed from oil-solvent mixtures depends to a large extent upon its crystal structure. The waxes present in the lower viscosity distillates tend to crystallize from oil-solvent solutions in very large crystals, while those in the higher viscosity distillates and residua form relatively small crystals. The size of crystal depends not only upon the nature of the oil fractions (34) but also upon the viscosity of the solution from which it crystallizes (41), and the manner in which the chilling is conducted. The character of the fraction may be controlled to some extent during the distillation process, and the viscosity of the medium from which the wax crystallizes may be regulated by addition of the solvent. Thus, the size of the crystal may be regulated to permit efficient separation of the wax from the oil-solvent solution. 

Measurements are made of the properties of boiling point (at an appropriate pressure), density, refractive index, refractive dispersion (for appropriate wave lengths), viscosity, critical solution temperature in one or more appropriate solvents, infrared absorption (normally in the range 2 to 15 microns), ultraviolet absorption (normally in the range 0.2 to 0.4 micron or 2000 to 4000 A.), elemental composition, and average molecular weight. 

The reaction between 3,5-diaminoanisole and acid dianhydrides in amide solvents (above all N-methyl-2-pyrrolidone, NMP) was conducted at room temperature. The process occurred in a homogeneous system and led to PCA with relatively high, reduced viscosities of solution (Table 5.1). 

Osaki, K., SchragJ.L. Viscoelastic properties of polymer solutions in high-viscosity solvents and limiting high-frequency behavior. I. Polystyrene and poly(a-methyl-styrene). Polymer J. (Japan) 2,541-549 (1971). 

Dreval.V.Ye., Tager,A.A., Fomina,A.S. Concentrated solutions of polymers. IV. Viscosity of solutions of polystyrene in various solvents. Polymer Sci. USSR 5,495-507 (1964) [Vysokomolekul. Soyedin. 5,1404 (1963). 

Specific Viscosity = TJtp ( solution - solvent)/y solvent... 

Solvents were initially selected primarily on the basis of the conductivity of their salt solutions, the classical example being propylene carbonate (PC). However, solutions based on PC on its own were soon found to cause poor cyclability of the lithium electrode, due to uncontrolled passivation phenomena. Solvent mixtures or blends were therefore developed and selection currently focuses on a combination of high dielectric solvents (e.g. ethylene carbonate, EC) with an alkyl carbonate (e.g. dimethy(carbonate, DMC), to stabilize the protective passivation film on the lithium electrode, and/or with a low viscosity solvent [e.g. 1,2-dimethoxyethane (DME) or methyl formate (MF)], to ensure adequate conductivity. 

Reduced viscosity = (t solution-t solvent)/t solvent for 1% solution in dimethyl formamide at 25° C. 

Lyophilic sols are true solutions of large molecules in a solvent, Solutions of starch, proteins, or polyvinyl alcohol in water are representative of numerous examples. Properties of these solutions at equilibrium (for example, density and viscosity) are regular functions of concentration and temperature, independent of the method of preparation. The solvent-macromolecule compound system may consist uf more than one phase, each phase in general containing both components. Thus, if a solid polymer is added to a solvent in an amount exceeding the solubility limit, the system will consist of a liquid phase (solvent with dissolved polymer) and a solid phase (polymer swollen with solvent, i.e., a polymer with dissolved solvent). 

Thus the existence of such inhomogeneity seems to be necessary to understand the decoupling of the self-diffusion from the viscosity for solutes having the same size as that of the solvent. The existence of such inhomogeneity has also been suggested by Taijus and Kivelson [89] from their computer simulation studies. 

---