Correlation of solute solubility in supercritical carbon dioxide using a new empirical equation

A new empirical equation is proposed to correlate solute solubility in supercritical carbon dioxide (SCCO₂). The new empirical model has four parameters per each solute that can be obtained by correlation of the experimental solubility data. The input variables of the equation are pressure, temperature and density of pure SCCO₂. The new equation is applied for correlation of solubility of 24 compounds in SCCO₂ at wide range of temperatures and pressures. The overall percent of absolute average relative deviation (%AARD) of the new equation for correlation of the experimental data is 6.54%. Comparison of the results of the present model with a three-parameter and a four-parameter empirical model demonstrates good accuracy of the new empirical model.     

A new model for predicting solute solubility in supercritical fluids based on the Wilson equation

In this work, a new model based on the Wilson solution theory was proposed for predicting the solubility of solids in supercritical fluid (SCF) with and without cosolvent(s) of binary and ternary systems via computation of activity coefficients. For binary systems the model contains two adjustable parameters, while for ternary systems there are four adjustable parameters. The calculated results of the proposed model were compared with that of the literature models, and it is shown that the proposed model is a more accurate one.     

Cohesion parameters for surfaces, pigments, and fillers

Conclusions  The surfaces of pigments, fillers, plastics, fibres, and other materials can be characterized by cohesion parameters. These have a solid fundamental basis. Greater insight into the make-up of a product is possible when one also has the cohesion parameters for the polymer and solvents which are used in connection with these pigments and fillers. The critical surface tension and wetting tension are single point determinations. Cohesion parameters allow a more complete characterization of surfaces than do these single point measurements, and at the same time allow insight as to how the single point measurements fit into the overall energy picture for the product. A simple test method based on the spontaneous spreading of small droplets of known liquids is suggested to determine whether or not a surface is contaminated.     

A correlation for thermal conductivity of liquid n-alkanes based on the Vogel-Tammann-Fulcher-Hesse equation

This paper demonstrates that thermal conductivity of liquid paraffin hydrocarbons of different molecular weights can be correlated properly and conveniently using the Vogel-Tammann-Fulcher-Hesse equation. This approach is advantageous for applications of practical importance because it leads to a simpler effective correlation with fewer empirically determined parameters while providing twice better accuracy than a previous empirical correlation utilizing cubic-polynomial equations. This is illustrated by analyzing and correlating the thermal conductivity data of several liquid n-alkanes.     

Hansen solubility parameters for a carbon fiber/epoxy composite

In this study, the physical affinity between an epoxy matrix and oxidized, unsized carbon fibers has been evaluated using Hansen solubility (cohesion) parameters (HSP). A strong physical compatibility has been shown, since their respective HSP are close. The use of a glassy carbon substrate as a model for unsized carbon fiber has been demonstrated as appropriate for the study of interactions between the materials in composite carbon fiber–epoxy systems. The HSP of glassy carbon are similar to those of carbon fibers and epoxy matrix.     

A new procedure for calculating Hansen solubility parameters of carbon nanotube/polymer composites

In this article, a new modeling and optimization procedure for Hansen solubility parameters (HSP) is developed. HSP values and the radius of interaction sphere for a solute can be determined by using this method based on experimental data at room temperature. The newly developed method could fit the experimental data better and get smaller radius of interaction sphere compared with the classical Hansen’s method. The HSP values of carbon nanotubes and polymer matrix are calculated to show the accuracy of the proposed approach. The physical affinity between the carbon nanotubes and polymer in the filler-polymer matrix system composite has been evaluated by their HSP spheres interaction.     

两维新溶解度参数和柴油脱蜡溶剂的选择

试图应用两维溶解度参数理论对能够改善柴油低温流动性能的脱蜡溶剂进行筛选。在建立两维平面坐标模型的基础上,计算了柴油中各组分和14种溶剂的两维溶解度参数,提出了用两维坐标图中溶剂与正构烷烃溶质的距离R_c作为是否相溶的判断依据。通过分析两维溶剂溶解度参数与萃取效果的关系,发现除2-丙醇外其他溶剂的正构烷烃萃取率随着R_c的增大而增大,表明可以依据溶剂的R_c选择柴油的脱蜡溶剂。同时发现物理溶解度参数Δ_p对溶剂的脱蜡性能影响很小,萃取过程主要受化学溶解度参数分量Δ_c的影响,且溶剂的偶极力是影响其脱蜡性能的主要因素。     

Use of solubility parameters for the preparation of hemodialysis membrances

The Solvent mixtures of acetone and ethanol (swelling agent) were selected for the preparation of cellulose acetate dialysis membranes using the solubility parameter concept. Increased concentration of ethanol or decreased concentration of cellulose acetate in the formulation resulted in membranes with higher dialysis rate constants but with decreased tensile strengths. The membranes prepared from 20 g of cellulose acetate per 100 ml of mixed solvent of 59.9 mole-% acetone and 40.1 mole-% ethanol were comparable to Cuprophane membrane but were better than those prepared by using formamide as a swelling agent.     

Determination of the parameters of the compressibility equation for a dinas mixture

Based on the molding of experimental samples from a dinas mixture and the determination of the apparent density of the samples calculated for the solid phase, we have established the values of the parameters of the compressibility equation, taking into account the residual and elastic deformation of the compact. Values of the molding pressure corresponding to the limiting density in the transition from a three-phase to a two-phase system have been determined as a function of the height of the mixture fill in the mold.     

Determination of the Hansen solubility parameters with a novel optimization method

The Hansen solubility parameters (HSPs) are useful for predicting solvent–solute affinity. In this study, the HSPs and the sphere radii (Ro's) of poly(ether sulfone), bitumen, and lignin were determined by a novel optimization method. A hybrid algorithm, which could locate multiple optima, was developed and used to solve optimization problems for maximizing the fitness (F) and minimizing both Ro and the numbers of good solvent and total outliers. For most selected samples, improved results with higher F and reduced Ro and number of outliers were obtained. The results clarify the correlations among three criteria for an optimal solubility sphere, namely, the smallest Ro, highest F, and lowest number of outliers. They can be satisfied simultaneously only when outliers are avoided; otherwise, a reduction in Ro decreases F but can retain the same outliers. Thereby, defining the solubility sphere as the one having the smallest Ro and the lowest number of outliers is more reasonable according to the physical significance in both cases. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016 , 133, 43328.     

Estimation of the equation of state exchange energy and entropy parameters of a polymer-solvent pair by intrinsic viscosity measurements

The intrinsic viscosity data of linear poly(4-chlorostyrene) in n-propylbenzene and isopropylbenzene were used to estimate the equation of state exchange energy (X₁₂) and entropy (Q₁₂) parameters. The quantities estimated for X₁₂ were 6.7 and 8.1 J cm^?3 and those of Q₁₂ were ?0.069 and ?0.063 J cm^?3 deg^?1 in n-propylbenzene and isopropylbenzene, respectively. The average values of the chain unperturbed dimension constant (K_o) and the characteristic ratio (C_x) were found to be 0.55 × 10^?3 dl mol^1/2g^?3/2 and 10.54, respectively, from the intrinsic viscosities measured at the corresponding θ-temperatures.     

Estimation of equation of state parameters for 1,1,1,2-tetrafluoroethane in a modified benedict-webb-rubin equation

Thermodynamic properties of refrigerants are of great importance in the design and simulation of heat pumps and refrigeration units. The parameter values in the modified Benedict-Webb-Rubin equation of state proposed by Lee and Kesler (1975) have been determined for HFC 134a with the Error-in-Variables Model. The types of data used for the parameter estimation have been: pressure-volume-temperature data for subcooled and superheated conditions, vapour pressures, saturated vapour and liquid volumes, isobaric arid isochoric heat capacities and second virial coefficients. Calculations carried out with the equation of state according to Lee and Kesler, with the parameters here proposed, agree well with experimental data for the fluid.     

Modified parameters for the Redlich-Kwong equation of state

Two new parameters are proposed for the Redlich-Kwong equation of state. They are developed for pure components at T>T_c with emphasis placed on the application of the Redlich-Kwong equation to vapor-liquid equilibrium studies. The proposed parameters reflect the departure from the experimental T_c and P_c values, and are related to the conventional parameters. Calculated critical isotherms of pure propane and hydrogen by means of the proposed method and two methods available in the literature are compared and discussed. A set of mixing rules is proposed for correlating vapor-liquid equilibrium data. Critical volumes and acentric factors of pure components are not required in the application of these mixing rules. Applicability of the proposed new parameters and mixing rules is demonstrated by the correlation of vapor-liquid equilibrium data for five binary systems at thirty-two isothermal conditions and by the prediction of the triple-values dew-point curve for the methane-n-butane mixtures. Based on a paper presented at the Research Seminar on “Vapor-Liquid Equilibria in Multicomponent Mixtures” November 2–6, 1975 at Jablonna, Poland.     

Application of a chemical group contribution technique for calculating solubility parameters of polymers

A chemical group contribution technique, based on the principle of additivity of molar attraction constants for groups in a molecule, has been used for determining the solubility parameters for several polyesters, polyethers and a few other types of polymers. The solubility parameter for a polymer is calculated by using the contributions for chemical groups reported in the literature with the resultant values found to compare favorably. For geometrical isomers of polymers, the calculated solubility parameters are identical but differ for positional substitution.     

A method for estimating both the solubility parameters and molar volumes of liquids

The solubility parameters and molar volumes of substances can be used, in conjunction with suitable theory, to provide estimates of the thermodynamic properties of solutions; the solubility characteristics of polymer-solvent systems and the estimation of the equilibrium uptake of liquids by polymers are examples of the type of practical problems that are amenable to treatment. For low molecular weight liquids, the solubility parameter, δ, is conveniently calculated using the expression δ = (ΔE_v/V)½, where ΔE_v is the energy of vaporization at a given temperature and V is the corresponding molar volume which is calculated from the known values of molecular weight and density. For high molecular weight polymers, the volatility is much too low for ΔE_v to be obtained directly and hence recourse must be made to indirect methods for estimating δ for these materials. One such widely used method is based on Small's additive group “molar-attraction constants” which when summed allow the estimation of δ from a knowledge of the structural formula of the material; however, the density must still be determined experimentally. The proposed method of estimating δ, also based on group additive constants is believed to be superior to Small's method for two reasons: (1) the contribution of a much larger number of functional groups have been evaluated, and (2) the method requires only a knowledge of the structural formula of the compound.     

Changes of solubility parameters during evaporation of solvents as a factor influencing the self-stratification of epoxy/acrylic systems

Behaviour of solutions of binary mixture of epoxy/acrylic resins during solvent evaporation was examined. Properties of various liquid compositions at different stages of solvent evaporation were characterised by their solubility parameters and surface tension. Both parameters were calculated from the weight fractions of particular components determined by gas chromatography (GC). Phase separation during solvent evaporation and self-stratification were observed and characterized using optical microscopy and FTIR methods. The results of investigations indicate the possibility of using these methods in order to foresee behaviour of binary compositions.     

Isolated methyl groups as new structural parameters for petroleum crudes

For the first time, the contents of isolated methyl groups, i.e. methyl groups bound to quaternary aliphatic or aromatic carbon, in crude oil samples were determined. As an analytical tool we used the ³J(H,H) modulated ¹H-NMR spin echo technique. Weighed amounts of hexamethyldisiloxane (HMDS) containing six isolated methyl groups were added to the samples to determine absolute concentrations. The contribution of isolated methyl carbon to total carbon was in the range of 3.0 to 6.9% methyl groups bound to aliphatic carbon, and 1.2 to 4.6% for methyl bound to aromatic carbon. Model compound mixtures of known composition were prepared to validate the new procedure. The procedure delivers accurate and precise results with regard to relative standard deviations of less than 1%.     

A new method for the determination of the solubility of disperse dyes

The solubility of sparingly soluble compounds, particularly when they are present in the finely dispersed state, is difficult to measure, especially at elevated temperature and pressure. To date there have been no simple methods of determination. A quick and very simple method is now presented, termed ‘solubility titration’, based on the idea that if the substance under test is added gradually in small amounts to a solvent or dilute solution, its extinction or light scattering in the u.v/visible region must change abruptly the moment the solubility is exceeded. Such is actually the case, and the solubility is found from the extinction or from the light scattered, at the point indicated by the intersection of two curves. This method was developed specifically to determine the water solubility of commercial disperse dyes under dyeing conditions, i.e. at 130d?C and elevated pressure (about 400 kPa). Tests gave precise, highly reproducible values.