Solubility parameter from viscosity measurements

Solubility Parameter from Viscosity Measurements. Based on the calculated values of Sftba, several solvents (with solubility parameters ranging from 14.5 to 19... 

Thus, one can calculate the solubility parameter from a knowledge of the heat of vaporization, A//m, and the molar volume, Vm- This is straightforward for many solvents and values of 8 have been tabulated by Barton (6). For polymers this is not easy since the heat of vaporization is not known and other methods have to be applied to determine the solubility parameter of various polymers. Several experimental methods such as the measurement of polymer swelling or intrinsic viscosity may be applied. Alternatively, 5 may be calculated from a knowledge of the molar attraction constants, G, of the various functional groups in the polymer (7, 8). The values of G for the various groups are assumed to be additive ... 

Luciani et al. (1998) critically examined the experimental methods used for the measurements of the interfacial coefficient in polymer blends as well as the theoretical models for its evaluation. A new working relation was derived that makes it possible to compute the interfacial tension from the chemical structure of two polymers. The calculations involve the determination of the dispersive, polar, and hydrogen-bonding parts of the solubility parameter from the tabulated group and bond contributions. The computed values for 46 blends were found to follow the experimental ones with a reasonable scatter of +/— 36 %. The authors mentioned also that since many experimental techniques have been developed for low-viscosity Newtonian fluids, most were irrelevant to industrial polymeric systems. For their studies, two were selected capillary breakup method and a newly developed method based on the retraction rate of deformed drop. 

The following components of solubility parameters for PPO have been obtained (177) Sd = 16.3 1, Sp = 4.7 0.5, 6h = 7.4 0.5, and So = 18.5 1.2 with units (J/mL)"/2. The determination was based on the use of three mixtures of solvents. For each mixture, the point of maximum interaction between the mixture and the polyol was obtained from the maximum value of the intrinsic viscosity. The parameter 8d measures dispersion 8p, polar bonding 5h, hydrogen bonding and 5q is the Hildebrand solubility parameter which is the radius vector of the other orthogonal solubility parameters. Water solubility of PPO has been determined using turbidimetric titration (178) (Table 7). 

Very little data on the Hildebrand solubility parameters of ionic liquid-solute systems is available to date. A study of eight ionic liquids using viscosity measurements in different solvents indicated polarities similar to allyl alcohol or dimethylsulfoxide [35], More recent work has shown that the solubility parameters can be reliably estimated from surface tension and density measurements [36], The equilibrium position of keto-enol tautomers in conjunction with quantitative H-NMR-, IR- and UV/Vis-spectroscopy has been studied in ionic liquids [37, 38], where the stabilisation of the enol form is favoured in non-polar solvents in general. Comparison to the relative tautomer ratios obtained in methanol and acetonitrile indicated that even hydrophobic (non-polar) [BTA]-based ionic liquids were more polar than these organic solvents. 

Figure 6-1. Influence of goodness of solvent, as measured by the solubility parameter, 6i, of the solvent, on the intrinsic viscosity. [17], of dissolved natural rubber and on the volume fraction, 02, of the cross-linked natural rubber polymer in aliphatic hydrocarbons, (O), long-chain esters, ( ), and long-chain ketones, (O). After data from G. M. Bristow and W. F. Watson. The solubility parameter is given in the traditional physical units.

The authors [91] proposed description of organic phase influence on limiting characteristics of polyurethanearylates (PUAr) interfacial polycondensation. As it is known [55], one from the methods of polymer solubility parameter 5 experimental determination is plotting of the dependence of intrinsic viscosity [t ], measured in several solvents, on this solvents solubility parameter 5 value. The smaller difference 6p-5J or the better solvent thermodynamical quality in respect of polymer is, the larger [q] is. The dependences [q](5 ) have usually belllike shape and such dependence maximum corresponds to 5 [55]. In Fig. 23 the dependence of on 5 of solvents, used as organic phase at PUAr interfacial polycondensation is adduced. The dependence q /S ) bell-like shape is obtained again and its maximum corresponds to 5 10 (cal/cm ), that is a reasonable estimation for PUAr [36, 55]. Let us note that all q values were determined in one solvent, which was not used at synthesis, namely, in mixture phenol-simm-tetrachloroethane. The dependence qj 4(5 ), adduced in Fig. 23, allows to make two conclusions. Firstly, the value q, reached in PUAr interfacial polycondensation process, is controlled by solvent thermodynamical qnality and the greatest... 

It is reasonably easy to use Eq. 26 to determine the solubility parameter of a solvent, but since the heat of vaporization of polymers is usually not known, other methods are needed to determine the solubility parameters of polymers. There are several experimental methods, based on polymer swelling measurements or on the determination of the intrinsic viscosity of polymer solutions. Alternatively, solubility parameters can be predicted from knowledge of the chemical structure of each component. The latter method is due to Small (72) and Hoy (73), who supplied values for molar attraction constants (G) of a large number of functional groups (Table 4). The constants G are additive. With these values it is possible to estimate the solubility parameter of any polymer using Eq. 28, where p represents the density and M the molecular weight of the polymer. 

Experimental data were found only for the total solubility parameter of the [TfjN]-series [29]. The Hildebrand solubility parameters as determined from intrinsic viscosity measurements in Ref. [29] are listed along with our calculated total solubility parameter values in Table 5,5,... 

Asphaltene content bears directly on the physical properties of the liquid product. Viscosity is of particular interest because of the importance of this parameter to operation of liquefaction plants and as a measure of the extent of liquefaction. The correlation between asphaltene content and the viscosity of the liquid has been a subject of a number of investigations (23-27). The logarithm of the viscosity ratio, In 7j/rj0 (where i and y0 are the viscosities of the solution and solvent, respectively) was found to be a linear function of concentration when asphaltene was redissolved in the pentane-soluble oil isolated from a coal-derived liquid (24). The slopes of these lines, termed the logarithmic viscosity numbers, are a measure of the contribution to the viscosity of a solution attributable to asphaltene. By comparison of logarithmic viscosity numbers of asphaltenes and their acidic and basic subfractions, it was determined that intermolecular association, which is especially strong between the acid and base subfractions, is responsible for a significant portion of the viscosity of these solutions. 

Since zero-C02 concentration is taken as a reference condition, the parameter is not a function of CO2. Then, f, oc, and jS can be determined from the PVT measurement of the neat polymer. There remains only gas concentration coefficient, (p, a. a. variable affected by CO2 dissolution. The gas expansion coefficient, (p, is determined by solubility measurements, the models with these parameter values could predict the viscosity of polymer/C02 single-phase mixtures. ... 

In Chapter 1 of this book, the necessary parameters for both RDE/RRDE analysis in ORR study, such as O2 solubility, O2 diffusion coefficient, and the viscosity of the aqueous electrolyte solutions, are discussed in depth in terms of their definitions, theoretical backgroimd, and experimental measurements. The effects of type/concentration of electrolyte, temperature, and pressure on values of these parameters are also discussed. To provide the readers with useful information, the values of these parameters are collected from the literature, and summarized in several tables. In addition, the values of both the O2 solubility and diffusion coefficient in Nafion membranes or ionomers are also listed in the tables. Hopefully, this chapter would be able to serve as a data source for the later chapters of this book, and also the readers could find it useful in their experimental data analysis. 

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