Solubility parameters fractional polarity

Three solution parameters that are used to describe solvency of the solvent blend in fundamental terms solubility parameter, fractional polarity, and hydrogen bonding index number (85). 

When viscometric measurements of ECH homopolymer fractions were obtained in benzene, the nonperturbed dimensions and the steric hindrance parameter were calculated (24). Erom experimental data collected on polymer solubiUty in 39 solvents and intrinsic viscosity measurements in 19 solvents, Hansen (30) model parameters, 5 and 5 could be deterrnined (24). The notation 5 symbolizes the dispersion forces or nonpolar interactions 5 a representation of the sum of 8 (polar interactions) and 8 (hydrogen bonding interactions). The homopolymer is soluble in solvents that have solubility parameters 6 > 7.9, 6 > 5.5, and 0.2 < <5.0 (31). SolubiUty was also determined using a method (32) in which 8 represents the solubiUty parameter... 

As already mentioned molecules cohere because of the presence of one or more of four types of forces, namely dispersion, dipole, induction and hydrogen bonding forces. In the case of aliphatic hydrocarbons the dispersion forces predominate. Many polymers and solvents, however, are said to be polar because they contain dipoles and these can enhance the total intermolecular attraction. It is generally considered that for solubility in such cases both the solubility parameter and the degree of polarity should match. This latter quality is usually expressed in terms of partial polarity which expresses the fraction of total forces due to the dipole bonds. Some figures for partial polarities of solvents are given in Table 5.5 but there is a serious lack of quantitative data on polymer partial polarities. At the present time a comparison of polarities has to be made on a commonsense rather than a quantitative approach. 

Further development of this concept (Long and Speight, 1989, 1990, 1997) involved the construction of a different type of compositional map using the molecular weight distribution and the molecular type distribution as coordinates. The separation involved the use of an adsorbent such as clay, and the fractions were characterized by solubility parameter as a measure of the polarity of the molecular types. The molecular weight distribution can be determined by gel... 

Measuring the overall solubility parameter of a petroleum fraction is time-consuming. Therefore, it is desirable to have a simpler, less time-consuming measurement that can be made on petroleum fractions that will correlate with the solubility parameter and thus give an alternative continuum in polarity. In fact, the hydrogen-to-carbon atomic ratio and other properties of petroleum fractions that can be correlated with the solubility parameter (Wiehe, 1992, 1995, 1996 Speight, 1994) also provide correlation for the behavior of crude oils. 

When the only effects that have to be taken into account are those of cavity formation in the solvent and the dispersion interactions, i.e., when both the solvent and the solute are non-polar, then Hildebrand s solubility parameter concept (Hildebrand and Scott 1950) provides good estimates of the solubility. The mole fraction of a gaseous solute, x2, in a solution in equilibrium at a partial pressure p2 of this gas, can be estimated from the following expression ... 

As we saw above (eqn.3.34), the solubility parameter concept provides a very simple rule for approximating the polarity of a mixture. For a binary mobile phase containing water (W) and methanol (Me) the sum of the two volume fractions should equal 1, hence... 

The polarity index or the solubility parameter may be used as a measure of solvent strength, which would be a measure of polarity in those cases. For reversed phase HPLC, solvent strength parameters have been proposed for the four most common solvents used, i.e. water (Si = 0), methanol (Si = 2.6), acetonitrile (Si = 3.2) and THF (Si = 4.5). Using these values water makes no contribution to the eluting power of the mobile phase and the solvent strength is measured by the volume fraction of organic modifier. 

Application of solubility parameter data is hindered by the multicomponent nature of humic substances, and homogeneous fractions are needed to obtain the necessary data for the macromolecules. Nevertheless, the available information shows that the best solvents for humic acids have polar,... 

Solubility maps usually show the soluble area of a resin in a variety of solvents and are usually based on the physical chemical constants of the solvents. We recognize the various solution parameters such as solubility parameter, internal pressure, dipole moment, fractional polarity, or the various measures of hydrogen bonding, but we have chosen solubility parameter (8), (the measure of all the intermolecular forces present in... 

As for every material, the behavior of cellulose derivatives is governed by equations in which solubility parameters or surface free energy terms are frequently included. For comparison purposes, it seemed opportune to collect recently published data (Table 8). Polarity is for most applications a relevant parameter and therefore fractional polarities xp were calculated from solubility parameters or surface free energies, Eq. (4) Sect. 2.3. 

Table 8. Experimentally determined and calculated values of the solubility parameter 6, as well as fractional polarities xp of various cellulose derivatives (subscript d is for dispersive, p for polar and h for hydrogen-bonding)1...

Riggs showed the solubility of a pitch in a series of solvents with increasing solubility parameters followed a bell shaped curve, with maximum solubility occurring when the solubility parameter of the solute and solvent were equal( ). In general, non-polar solvents with total solubility parameters ranging from 8.0-9.5 were desirable for extracting mesophase forming fractions from pitches. In this... 

Product Dielectric constant at 20°C, 10 kHz Solubility parameter 6, cal/cm Fractional polarity... 

The dielectric constant is governed by the ease of formation of dipoles under the influence of electric forces in the solvent. The molecular weight is therefore not expected to have an effect on the dielectric constant but the polarity of the product, as expressed by its Hildebrand solubility parameter and fractional polarity (for more detail see chapter on solvent power), have a pronounced influence. This is demonstrated by the homologous series of -alcohols, where the solubility parameter and fractional polarity decrease from 14.5 and 0.388 respectively for methanol to 10.9 and 0.074 for -pentanol. A few examples taken from the second series are shown in Table 2.9. 

Nelson, Hemwall and Edwards have proposed a three parameter system which shows some similarity with that of Crowley, Teague and Lowe. It also uses the Hildebrand solubility parameter and a fractional polarity as suggested by Gardon, together with a net hydrogen bond index. This latter parameter is an attempt to... 

For this reason two-dimensional plots are generally made when using the Nelson, Hemwall and Edwards parameter system. In the first instance solubility maps were constructed of the fractional polarity against the Hildebrand solubility parameter, as shown in Figure 2.9. 

In a later stage it appeared to be more convenient to plot the hydrogen bond index against the Hildebrand solubility parameter as demonstrated in Figure 2.10. In this way of presentation contours of the maximum permissible fractional polarity can be indicated, which gives a good, and in practice very satisfactory, presentation of the three-dimensional case. 

Solvents have solubility parameters which fall within the contours of the map. However, at a given Hildebrand solubility parameter and hydrogen bonding index, the higher the solvent fractional polarity, the lower... 

Solubility parameter Hydrogen bond index Fractional polarity Nitro cellulose dil ratio Nitro cellulose dil ratio (J/cm ) /2 24.5... 

Auto ignition temperature Upper flammability limit Lower flammability limit Viscosity Refractive index Solubility in water Solubility of water Solubility parameter Hydrogen bond index Fractional polarity Nitro cellulose dil ratio Nitro cellulose dil ratio Surface tension Specific heat liquid Latent heat Dielectric constant Antoine constant A Antoine constant B Antoine constant C Heat of combustion UN number IMO classification ADR/RID classification UK exposure limits USA exposure limits German exposure limits EU classification EU risk phrases EU safety phrases... 

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