Relationship solvent solubility parameter

Figure 14.23 Relationship between the critical strain of a polymer and the solvent solubility parameter. (From Ref. 24.)...

The Eq. (32) displays an interesting fact, namely, antibatness of the dependences of fractal dimension D on components of solvent solubility parameter 8 and 8. As it follows from the indicated relationship, A8 increase (i.e., 8 enhancement for fixed polymer) results to Z) growth and 8 increase—in its reduction. In addition the Eq. (32) form assumes stronger (power one) dependence D. on 8 than on 8. At the same time polymer solubility range, that is, the range A8, in which changes within the limits of 1.50-2.0, becomes wider at 8 growth [24]. 

Activity Coefficients. The relationships between solvent solubility parameters and solvent activity coefficients y, can be obtained in regular solutions by the relationship... 

The rate constants in organic reaction in a solvent generally reflect the solvent effect. Various empirical measures of the solvent effect have been proposed and correlated with the reaction rate constant [5]. Of these, some measures have a linear relation to the solubility parameter of the solvent. The logarithms of kj and k2/ki were plotted against the solubility parameter of toluene, NMP and DMSO[6] in Fig. 2. As shown in Fig.2, the plots satisfied the linear relationship. The solvent polarity is increased by the increase of solubility parameter of the solvent. It may be assumed that increase of unstability and solvation of Ci due to the increase of solvent polarity make the dissociation reaction of Ci and the reaction between Ci and COisuch as SNi by solvation[7] easier, respectively, and then, k2/ki and ks increases as increasing the solubility parameter as shown in Fig. 2. 

Fig.2. Relationship between reaction rate constant and solubility parameter of solvent in the reaction of CO2 with GMA using Aliquat 336 at 85 C.

Solubility parameters can be a useful guide to solvent selection, but precise quantitative relationships between solvent properties and extraction rates are not yet possible [37]. As an illustrative example we mention extraction of Irganox 1010 from PP [37]. Freeze-ground PP was extracted at 120 °C with 2-propanol,... 

The polymer-solvent interaction parameter can be estimated by using the solubility parameters for the polymer and solvent. An approximate relationship between these parameters is... 

For the solubility of TPA in prepolymer, no data are available and the polymer-solvent interaction parameter X of the Flory-Huggins relationship is not accurately known. No experimental data are available for the vapour pressures of dimer or trimer. The published values for the diffusion coefficient of EG in solid and molten PET vary by orders of magnitude. For the diffusion of water, acetaldehyde and DEG in polymer, no reliable data are available. It is not even agreed upon if the mutual diffusion coefficients depend on the polymer molecular weight or on the melt viscosity, and if they are linear or exponential functions of temperature. Molecular modelling, accompanied by the rapid growth of computer performance, will hopefully help to solve this problem in the near future. The mass-transfer mechanisms for by-products in solid PET are not established, and the dependency of the solid-state polycondensation rate on crystallinity is still a matter of assumptions. 

As early as 1926, Hildebrand showed a relationship between solubility and the internal pressure of the solvent, and in 1931 Scatchard incorporated the CED concept into Hildebrand s equation. This led to the concept of a solubility parameter, S, which is the square root of CED. Thus, as shown below, the solubility parameter S for nonpolar solvents is equal to the square root of the heat of vaporization per unit volume ... 

TheD term accounts for part of the effects of solution enthalpy. Enthalpy of mixing results when the solute-solvent interaction force is different from the solute-solute and the solvent-solvent interactions. Intermolecularforces can be further characterized as dispersion, dipolar, and hydrogen-bond forces. In the mobile order solubility approach, dispersion and dipolar forces were not separated. The effects of these two forces on solubility were expressed in terms of modiLed solubility parameters, S andSj. The relationship between solubility and solubility parameters can be derived in the... 

Hildebrand s solubility parameter 8 = [Av//° - ///]/ V)1/2 is a useful guide for the solubility of nonpolar solutes in nonpolar solvents, but a poor predictor for solubilities in water. In general, the more polar a solvent, or solute, the better it dissolves in water, but again, there is no clear relationship between any... 

The establishment of relationships between molecular sizes/shape, and structure of compounds in pitches and solubilities in solvents of known solubility parameters. 

Obviously the value a is dependent on the nature of the polymer-solvent interaction in theta solvents a = 0.5, while in "good" solvents a 0.8. Therefore some relationship between a and the solubility parameter of the solvent, r)s, may be expected. 

The value of kd was obtained from the determination of triplet lifetimes by measuring the decay of phosphorescence and found to be insensitive to changes in solvent polarity. The k2 values derived from Eqs. 10 and 11 were correlated with solvent parameters using the linear solvation energy relationship described by Abraham, Kamlet and Taft and co-workers [18] (Eq. 12), which relates rate constants (k) to four different solvation parameters (1) or the square of the Hildebrand solubility parameter (solvent cohesive energy density), (2) n or solvent dipolarity or polarizability, (3) a, or solvent hydrogen bond donor acidity (solvent electrophilic assistance), and (4) or solvent hydrogen bond acceptor basicity (solvent nucleophilic assistance). 

Small [36] showed that most of the reported 8 can be estimated by the last of the above three relationships, on the basis of the molecular structure of the solvent. He used this method to calculate the solubility parameter of poly(styrene) to obtain a value, 5pol = 9.12 (cal/mL)1 2, which is within the range of the experimental 8-values [8.6 to 9.7 (cal/mL)1/2] reported for this polymer [34, 37 39], [note that (joule/mL)1/2 = 2.046 (cal/mL)1/2]. 

Sometimes, Hildebrand s solubility parameter 8 has been incorrectly used in linear Gibbs energy relationships cf. for example [96, 97, 226, 255]. Since in linear Gibbs energy relationships the correlated solvent-dependent solute properties e.g. Ig K, Ig k, h v) are proportional to Gibbs energy changes of reaction or activation (AG, AG ) and... 

Equations (5) follow from the functional relationship of interaction energies to properties of the two interacting species (/) a is therefore a measure of the interaction strength of the adsorbent surface. It is believed that in most LSC systems the solution terms are effectively zero, as a result of cancellation of solvent-solute interactions in the two phases (/). Arguments in terms of solubility parameter theory lead to a similar conclusion 28) Inserting Eqs. (5) into Eq. (4), with neglect of the solution terms, then gives... 

HIPS resists damage to properties from exposure to water, alkalis and dilute mineral acids. It is swollen by some organic solvents and dissolved by others in a relationship governed by the difference between the solubility parameter of the continuous phase and that of the solvent. HIPS is particularly susceptible to damage when exposed to chlorinated and aromatic hydrocarbons. 

By itself the solubility parameter can explain the behaviour of only a relatively small group of solvents - those with little or no polarity and those unable to participate in hydrogenbonding interactions. The difference between the solubility parameters expressed as (dj - 2) will give an indication of solubility relationships. 

Other molecular properties have been also proposed to model the hydrophobic interactions. The parachor, which is related to the surface tension of a compound (139, 140) represents mainly the intermolecular interactions in a liquid. The Hildebrand-Scott solubility parameter, 6, (141) is related to intermolecular van der Waals forces and the closely related molar attraction constant, F, is obtained by multiplying 6 by the molar volume (142). The partition coefficient between two solvents can be obtained from the solubility parameters and the molar volumes of the solute and the solvents (193). This relationship is based on regular solution theory (194) and the assumption that the partial molar volumes of the solute is not different from its molar volume. Recently this has been criticized and a new derivation was proposed (195) in which the partial molar volumes are taken into account. The molar refractivity, MR, is related to dispersion forces and can be obtained as a sum of the partial molar refractivi-ties assigned to atoms and bonds (140, 143). These parameters have been compared (144) to establish their relative applicability to correlations with biological activity. The conclusion was that logP and molecular refractivity were the best parameters. Parameters obtained from high pressure liquid chromatography (144,... 

Solute-solvent interactions were largely studied and modeled by Linear Solvation Energy Relationships and the —> Hildebrand solubility parameter. 

Solubility parameters of solvents can be correlated with the structure, molecular weight, and density of the solvent molecule. According to the additive method of Small [15], the solubility parameter is calculated from a set of additive constants, F, called molar attraction constants, by the relationship. ... 

The majority of studies on the structure and properties of Nafion membranes are very often performed on the dry or humidified samples while many important applications of these materials are in the "wet form. The knowledge pertaining to the interaction between the solvents and the polymer by the use of the solubility parameter should facilitate the understanding of the structure-property-performance relationship. Investigations of ionic transport (13), spectroscopic properties (14) and dielectric loss tangent (12) of the membrane in light of the solubility parameter could prove to be an interesting and perhaps profitable line of inquiry. 

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