Solubility parameter acids

For example, nylon 66 will dissolve in formic acid, glacial acetic acid, phenol and cresol, four solvents which not only have similar solubility parameters but also are capable of acting as proton donors whilst the carbonyl groups on the nylon act as proton acceptors (Figure 5.6). 

As may be expected of an amorphous polymer in the middle range of the solubility parameter table, poly(methyl methacrylate) is soluble in a number of solvents with similar solubility parameters. Some examples were given in the previous section. The polymer is attacked by mineral acids but is resistant to alkalis, water and most aqueous inorganic salt solutions. A number of organic materials although not solvents may cause crazing and cracking, e.g. aliphatic alcohols. 

The solubility parameter is about 19.2MPa and being amorphous they dissolve in such solvents as tetrahydrofuran, mesityl oxide, diacetone alcohol and dioxane. Since the main chain is composed of stable C—C and C—O—C linkages the polymer is relatively stable to chemical attack, particularly from acids and alkalis. As already mentioned, the pendant hydroxyl groups are reactive and provide a site for cross-linking. 

Being cross-linked, the resin will not dissolve without decomposition but will be swollen by liquids of similar solubility parameter to the cured resin. The chemical resistance is as much dependent on the hardener as on the resin since these two will determine the nature of the linkages formed. The acidic hardeners form ester groups which will be less resistant to alkalis. 

The fluids have reasonably good chemical resistance but are attacked by concentrated mineral acids and alkalis. They are soluble in aliphatic, aromatic and chlorinated hydrocarbons, which is to be expected from the low solubility parameter of 14.9 MPa. They are insoluble in solvents of higher solubility parameter such as acetone, ethylene glycol and water. They are themselves very poor solvents. Some physical properties of the dimethylsilicone fluids are summarised in Table 29.2. 

Numerous reports of comparable levels of success in correlating adhesion performance with the Scatchard-Hildebrand solubility parameters can be found in the literature [116,120-127], but failures of this approach have also been documented [128-132J. Particularly revealing are cases in which failure was attributed to the inability of the Scatchard-Hildebrand solubility parameter to adequately account for donor-acceptor (acid-base) interactions [130,132]. Useful reviews of the use of solubility parameters for choosing block copolymer compatibilizers have been prepared by Ohm [133] and by Gaylord [134]. General reviews of the use of solubility parameters in polymer science have been given by Barton [135], Van Krevelen [114], and Hansen [136]. 

As pointed out earlier, acrylics differ from the commonly used rubber precursors for PSA formulation in the fact that they often incorporate polar monomers, such as acrylic acid, A-vinyl pyrrolidone, vinyl acetate, or acrylamide. As a result, the solubility parameters of acrylic polymers are typically higher than those of rubbers, like polyisoprenes or polybutadienes. 

The other class of acrylic compatible tackifiers includes those based on ter-penes. Terpenes are monomers obtained by wood extraction or directly from pine tree sap. To make the polyterpene tackifiers, the monomers have to be polymerized under cationic conditions, typically with Lewis acid catalysis. To adjust properties such as solubility parameter and softening point, other materials such as styrene, phenol, limonene (derived from citrus peels), and others may be copolymerized with the terpenes. 

The parameters a and p indicate the capacity of a solvent to donate or accept a hydrogen bond from a solute, i.e., the solvent s hydrogen bond acidity or basicity. % is intended to reflect van der Waals-type solute-solvent interactions (dipolar, dispersion, exchange-repulsion, etc.). Equation (43) was subsequently expanded to include a term representing the need to create a cavity for the solute (and thus to interrupt solvent-solvent interactions).188 For this purpose was used the Hildebrand solubility parameter, 5, which is defined as the square root of the solvent s energy of vaporization per unit volume.189 Thus Eq. (43) becomes,190... 

Polymer Solubility. The modified polymers were soluble in DMSO, dimethylacetamide, dimethylformamide and formic acid. They were insoluble in water, methanol and xylene. Above about 57% degree of substitution, the polymers were also soluble in butyrolactone and acetic acid. Solubility parameters were determined for each polymer by the titration procedure as described in the literature (65). The polymer was dissolved in DMSO and titrated with xylene for the low end of the solubility parameter and a second DMSO solution was titrated with water for the high end of the solubility parameter range. These solubility parameters and some other solubility data are summarized in Table II. 

It is shown that the solubility of fullerenes in vegetable oils can be predicted and justified on the basis of the solubility parameters of C60 and C70 and of the glycerol esters of fatty acids. A detailed procedure for the calculation of the solubility parameters of fullerenes and vegetable oils by group increment is reported. 

Keywords Adducts, C60, C70, esters of fatty acid, excipients, fatty acids, fullerenes, glycerol esters of fatty acids, grafting, group increment method, solubility, solubility parameter, vehicles for drug delivery, vegetable oils, triglycerides... 

This chapter shows that the solubility of C60 and C70 fullerenes can be predicted from the solubility parameter of these two molecules and the calculated solubility parameters of fatty acids and their esters. Furthermore, the solubility of C60 and C70 fullerenes in a series of vegetable oils and fatty acid esters will be presented and discussed. 

The Solubility Parameter of Fatty Acids and Fatty Acids Esters of Glycerol... 

Being a mixture of different fatty acids esters of glycerol, the calculation with group increment of the solubility parameter of vegetable oils presents some... 

Table 13.2 Solubility parameters of fatty acid and vegetable oils...

The calculated solubility parameter derived from the Van Krevelen approach has been compared with the experimental solubility parameters of C60 and C70 reported in the literature and derived experimentally. An excellent agreement has been found between the calculated and the experimental <5d values. A comparison with the calculated solubility parameter of the vegetable oils, under certain conditions, permits to show that a good solubility of fullerenes in glycerol esters of fatty acids can be expected. Fulleiene solubility in molten free fatty acids can be predicted on the basis of solubility parameters comparison and it has been verified by dissolving C60 and C70 in molten fatty acids. 

Fig. 4.22 Comparison of measured and calculated distribution ratios of americi-um(III)-terpyridine-decanoic acid complexes between 0.05 M HNOj and various organic solvent combinations. The calculated values are obtained with the Hansen partial solubility parameters. (From Ref. 45.)... 

Next we consider the dispersion polymerization by polyaddition. In a typical method to prepare polyimide particles, polyamic acid solution is first obtained by coupling of pyromellitic dianhydride and oxy-dianiline, and then by heating the solution. The condensation reaction on heating causes crystallization of polyimide in a spherical form (Fig. 11.2.5, left) (33). However, on the contrary to this conventional method, polyamic acid microspheres could be obtained by dispersion polymerization if an appropriate medium is chosen (34). When a solvent that has a solubility parameter around 17 Mpa is used, submicrometer-sized monodisperse polyamic acid parti-... 

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