Solubility coefficient poly

Many computational studies of the permeation of small gas molecules through polymers have appeared, which were designed to analyze, on an atomic scale, diffusion mechanisms or to calculate the diffusion coefficient and the solubility parameters. Most of these studies have dealt with flexible polymer chains of relatively simple structure such as polyethylene, polypropylene, and poly-(isobutylene) [49,50,51,52,53], There are, however, a few reports on polymers consisting of stiff chains. For example, Mooney and MacElroy [54] studied the diffusion of small molecules in semicrystalline aromatic polymers and Cuthbert et al. [55] have calculated the Henry s law constant for a number of small molecules in polystyrene and studied the effect of box size on the calculated Henry s law constants. Most of these reports are limited to the calculation of solubility coefficients at a single temperature and in the zero-pressure limit. However, there are few reports on the calculation of solubilities at higher pressures, for example the reports by de Pablo et al. [56] on the calculation of solubilities of alkanes in polyethylene, by Abu-Shargh [53] on the calculation of solubility of propene in polypropylene, and by Lim et al. [47] on the sorption of methane and carbon dioxide in amorphous polyetherimide. In the former two cases, the authors have used Gibbs ensemble Monte Carlo method [41,57] to do the calculations, and in the latter case, the authors have used an equation-of-state method to describe the gas phase. 

Fig. 1. Solubility coefficients for a number of gases in various polymers above their j ass transition temperature. poly methyl vinyl ether) polyfvinyl acetate) a poly(methyl vinyl ketone) poly-(methyl acrylate) OFEP o poly-(dimethyl siloxane) o polytphenyl siloxane). The solid line is that for natural rubber (Van Amerongen and Barret, see Ref. l, p. 65)...

Besides the above conventional effects, Chapter 3 summarizes data suggesting the ability of some gases to sorb and diffuse inside the actual crystals of poly(4-methyl-l-pentene) (68,69). Finally, Chapter 3 considers liquid crystalline polymers, which seem to form a new class of materials in terms of barrier responses(57). The high barrier nature of liquid crystal polymers appears to be largely due to their unusually low solubility coefficients for typical penetrants. This is quite different from the case for most high barriers like EVOH, and polyacrylonitrile that typically function due to the unusually low mobilities of penetrants in their matrices (70). ... 

Fig. 1. Solubility coefficients for a number of gases in various polymers above their glass transition temperature. poly(methyl vinyl ether) poly(vinyl acetate) a...

In this section, we test the behavior of the NET-GP procedure for a gas-polymer mixture whose solubility has been characterized in both equilibrium and non-equilibrium conditions, that is, above and below the glass transition temperature Tg of the polymer. In Figure 2.1 we plot the value of the infinite dilution solubility coefficient of CO2 in poly(bisphenol-A) carbonate (PC) as a function of the inverse absolute temperature, as measured by Wang and Kamiya l The infinite dilution solubility coefficient, Sq, expressed in cm (STP)/(cm atm), is the slope of the solubility isotherm, in the limit of very low pressures ... 

In contrast to the LCP results just presented, in glassy polymers used as gas separation membranes, free volume influences diffusion coefficients much more than solubility coefficients. Figure 6 provides an example of this effect. In this figure, the solubility, diffusivity, and permeability of methane in a series of glassy, aromatic, amorphous poly(isophthalamides) [PIPAs] are presented as a function of the fractional free volume in the polymer matrix. (More complete descriptions of the transport properties of this family of materials are available elsewhere (59, 40)). The fractional free volume is manipulated systematically in this family of glassy polymers by synthesizing polymers with different substituent and backbone elements as shown in... 

Table 7-5. Permeability Coefficient P, Diffusion Coefficient D, and Solubility Coefficient S of Various Gases in Vulcanized cis-1,4-Poly isoprene) at 25° C...

The permeability, diffusion, and solubility coefficients for the gases as well as the ideal separation factors for gas pairs have been determined. A poly(imide-siloxane) with 20% siloxane content shows the best compromise with very high permeability and a still high permselectivity for the CO2/CH4 gas pair [12]. 

Here, Si and 82m 6 the solubility coefficients of those molecules of species 1 and 2 wbicb dissolve according to Henry s law. The utility of such a mbtture sorption isotherm model has been verified (see, for example, Sanders et al. (1984) for a mixture of CO2 and C2H4 in poly(metbyl methacrylate)). 

Poly (vinylchloride)-polypyrrole composite film was prepared by allowing the oxidative polymerization to take place in PVC matrix with diffused pyrrole. The PVC film was immersed in a swelling solution containing pyrrole so that the pyrrole monomer could diffuse into the polymer matrix and then subsequently polymerized in an oxidative solutions containing oxidant in an binary solvent system of similar solubility coefficients with PVC film. Mixture of acetone, n-hexane and pyrrole was chosen as a diffusion solution because it yields highly conductive and transparent composite film with good processability. 

Permeability, Diffusion and Solubility Coefficients of Alkanes Through Santoprene (Blend of Ethylene-Propylene Copolymer and Isotactic Poly(propylene)) Permeability, Diffusion and Solubility Coefficients of Esters Through Poly(epichlorohydrin)... 

Permeability, Diffusion and Solubility Coefficients of Esters through Poly(epichlorohydrin) VI/567... 

Figure 9.5 shows the dependence of the solubility coefficient on temperature in the range 250 K< T 400 K. As expected, solubility decreases with temperature that is, as the temperature increases, the gas molecules in the experiment become more difficult to condense. This behavior is in agreement with the experiments (CO2 in PET ) and simulations [CO2 and He in PE ° CO2 and CH4 in polyetherimide"" CH4 and CO2 in HDPE" n-alkanes in poly(dimethylsilamethylene)" and O2, N2, and CH4 in PE for long and short chains ]. 

Partition Coefficients of nonvl-phenyl-poly-(ethoxy)-ethanol (NPE) Surfactants. The solubility of surfactants in water and hydrophobic solvents is well documented (11,12,22), but only a few attempts at measuring partition coefficients between immiscible liquids have been reported (2,4,9,10). Partition coefficients of surfactants are of theoretical interest because of their relation to observed surfactant properties such as emulsification, wetting and detergency. Partition coefficients (K ) may be also of considerable practical value for predicting surfactant recov and recycling in industrial processes. For example, in the cold water extraction of tar sand, an effective surfactant with a high Kp could be efficiently recycled in the process water and would not follow the bitumen into the upgrading stream. 

Considering the rather complicated processes that take place during dissolution it is not surprising that some systems show peculiar behavior. For example, while solubility generally increases with temperature, there are also polymers that exhibit a negative temperature coefficient of solubility in certain solvents. Thus, poly(ethylene oxide), poly(N-isopropylacrylamide), or poly(methyl vinyl ether) dissolve in water at room temperature but precipitate upon warming. This behavior is found for all polymer-solvent systems showing a lower critical solution temperature (LCST). It can be explained by the temperature-dependent... 

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