Modeling of Nitrogen and Carbon Dioxide Solubility in Alternative Fuels at High Pressures Using the Soave‐Redlich‐Kwong Equation of State

In this paper, the Soave‐Redlich‐Kwong equation of state with quadratic mixing rule has been tested for correlation of vapor‐liquid equilibria (VLE) at high pressures in the binary nitrogen + dimethyl ether, dimethyl ether + methanol, nitrogen + methanol, carbon dioxide + dimethyl ether and carbon dioxide + methanol systems. The interaction parameters k_ij were evaluated for each binary pair and used for prediction of VLE in the ternary nitrogen + dimethyl ether + methanol and carbon dioxide + dimethyl ether + methanol systems at high pressures. The results of correlation and prediction are discussed.     

A study of some equation‐of‐state parameters of poly(methylhydrosiloxane‐co‐dimethylsiloxane) with some solvents by gas chromatography

Trace amount of methyl acetate, ethyl acetate, tert‐butyl acetate, pentane, hexane, and heptane were passed through the chromatographic column loaded with poly(methylhydrosiloxane‐co‐dimethylsiloxane) coated on Chromosorb W. The retention diagrams of the solvents on the copolymer were plotted by means of specific retention volumes at temperatures between 40 and 80°C by inverse gas chromatography technique. In this study, some thermodynamic interaction parameters such as Flory–Huggins polymer–solvent interaction parameter, equation‐of‐state polymer–solvent interaction parameter, effective exchange energy parameter, and weight fraction activity coefficients at infinite dilution of the solvent were determined. Then, the exchange enthalpy parameter and entropy parameter were determined by using a relation for the enthalpy interaction parameter of the equation‐of‐state theory, which is arranged for the inverse gas chromatography conditions. Later, the partial molar heat of sorption and the partial molar heat of mixing were obtained. The solubility parameter of this copolymer was determined as 6.64 (cal/cm³)^1/2 at room temperature. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 104: 1627–1631, 2007     

UNIQUAC Interaction Parameters with Closure for Imidazolium Based Ionic Liquid Systems Using Genetic Algorithm

Ionic liquids (ILs) are being considered as favourable solvents for liquid‐liquid extraction. Ternary phase equilibria containing the ionic liquid based systems have been reported in the literature for aromatic‐aliphatic‐IL as well as aliphatic‐alcohol‐IL ternary systems. In this work global optimization has been used for the prediction of UNIQUAC interaction parameters for IL based systems. The twin concepts of closure equation and global optimization via Genetic Algorithm (GA) have been benchmarked and tested on 88 aromatic and 28 hydrogen bonding multi‐component systems. For the aromatic systems the rmsd values obtained with closure equation are ～20 percent better than without closure equation and ～50 percent better than literature. Similarly for hydrogen bonding systems with closure equation gives ～20 percent better rmsd values than without closure equations with an overall improvement of ～60 percent. After this rigorous testing we have applied this procedure on 29 imidazolium based IL ternary systems. Improvements in rmsds with closure have been ～6 percent better than without closure.     

Water content of light n‐alkanes: New measurements and cubic‐plus‐association equation of state modeling

Light hydrocarbon gases such as methane, ethane, propane, and butane or other so called gaseous solvents have been suggested as steam additives to improve bitumen recovery and energy efficiency. The water content of these gases is one of the key requirements in the simulation and design of solvent‐aided thermal heavy oil recovery processes. In this work, we present new experimental data for the water content of these gases at high temperatures (up to 493.15 K) and moderate pressures (P < 6 MPa). The experimental data was regenerated using the cubic‐plus‐association equation of state. The Soave–Redlich–Kwong equation of state is used to treat the physical interactions. The association interactions are captured using Wertheim's first‐order thermodynamic perturbation theory. A set of binary interaction parameters is proposed to calculate the water content of methane, ethane, propane, and n‐butane at the operating conditions of the thermal heavy oil and bitumen recovery processes. © 2016 American Institute of Chemical Engineers AIChE J, 63: 1384–1389, 2017     

On the use of pressure‐volume‐temperature data of polyethylene liquids for the determination of their solubility and interaction parameters

Specific volumes of high‐density and low‐density polyethylene liquids at several elevated temperatures and pressures were measured. The measured specific volumes were then used to estimate the thermal expansion coefficients $\left( {{\rm \alpha = }\frac{{\rm 1}}{v}\left( {\frac{{\partial v}}{{\partial T}}} \right)_P } \right)$ and isothermal compressibility $\left( {{\rm \beta = } - \frac{{\rm 1}}{v}\left( {\frac{{\partial v}}{{\partial P}}} \right)_T } \right)$ of the polymers. Two different approaches were used in which one was simply to fit the raw data by second order polynomials to obtain (?v/?T)_P and (?v/?P)_T, while the other by the Sanchez‐Lacombe (S‐L) equation of state. It was found that the resultant α and β obtained from the above methods differ significantly, indicating that the S‐L equation of state may not be suitable for determining α and β at elevated temperatures. When these two sets of α and β were used to calculate the corresponding solubility parameters and then the Flory‐Huggins interaction parameters (χ) of the polymers, the results also differ considerably. Nonetheless, χ obtained from the first method agrees well with the results obtained from small angle neutron scattering measurements while the S‐L equation of state method does not. The current results suggest that solubility and interaction parameters obtained from pressure‐volume‐temperature experiments depend critically on the manner by which the data analysis is performed. Polym. Eng. Sci. 44:853–860, 2004. © 2004 Society of Plastics Engineers.     

Describing the sorption characteristics of a ternary system of benzene (1) and alcohol (2) in a nonporous polymer membrane (3) by the Flory–Huggins model

The Flory–Huggins equation was used to describe results of total and preferential sorption measurements for the binary liquid mixture of benzene (1) and alcohol (2) in one of two nonporous polymer membranes (3), low‐density polyethylene (LDPE) and Nafion membrane. The concentration dependence of binary and ternary interaction parameters was determined. The interaction parameters for the benzene – methanol binary mixture were obtained from binary vapor‐liquid equilibrium data in the literature to decrease the number of adjusted parameters. The results show that use of a ternary interaction parameter is necessary. Data treatment was performed assuming either no crystallinity or an average crystallinity typical for the studied membranes. Subsequently, the limiting activity coefficients of solutes in LDPE were calculated from the values of the interaction parameters and their values compared to values of the limiting activity coefficients of benzene and methanol in hypothetical liquid alkane with the same density as LDPE obtained by the UNIFAC method. POLYM. ENG. SCI., 55:1187–1195, 2015. © 2014 Society of Plastics Engineers     

The role of fiber bundle interaction forces in non‐isothermal compression molding of thermoplastic composites

The non‐isothermal flow during compression molding of thermoplastic‐based composites having a planar, randomly oriented fiber structure has been investigated. Local interactions at the bundle‐bundle level were measured and a constitutive equation was derived to describe the shear and squeeze flow of the composites. This equation contains only micro‐mechanics‐related variables, and accounts for the temperature dependence of the interaction forces. The flow of the material under industrial processing conditions can thus be related to the deformation mechanisms of the reinforcement structure at the scale of the individual fibers Good agreement was obtained between the predicted and experimentally observed theological behavior of the composites in both shear and squeeze flow. The use of this approach to analyze the industrial molding of complex‐shaped parts is dis cussed.     

1,2,3‐triazole crosslinked polymers as binders for solid rocket propellants

In this study, 1,2,3‐triazole crosslinked polymers were synthesized as a new binder for solid rocket propellant systems by reacting the azide groups of the polymer with the ethynyl groups of a dipolarophile curing agent. All the mixtures were cured in an oven at 52°C for 7 days, and the curing reactivity of the products was analyzed using a Fourier transform‐infrared spectrometer. The carbonyl group adjacent to the triple bond, which acts as an electron‐withdrawing group, considerably accelerated the 1,3‐dipolar cycloaddition reaction between the azide and ethynyl functional groups, affording rubbery materials. The modulus of the polymers increased whereas the elongation at the break decreased with increasing ratio of the crosslinker to the prepolymer, resulting in highly crosslinked polymers. The molecular weights between the crosslinking points and interaction parameters of the 1,2,3‐triazole crosslinked polymers were determined from the swelling data, Flory–Rehner equation, and Mooney–Rivlin equation. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014 , 131, 40594.     

Solubility of methane in glycols at elevated pressures

The solubility of methane in ethylene glycol and in diethylene glycol has been determined at temperatures in the range 25 to 125 °C at pressures up to 20.4 MPa. The experimental results were correlated by the Peng-Robinson (1976) equation of state, and interaction parameters have been obtained for these systems. Henry's constants were derived for comparison with data from the literature.     

Modeling of solid–liquid equilibria for polyethylene and polypropylene solutions with equations of state

We modeled solid–liquid equilibria (SLEs) in polyethylene and polypropylene solutions with a Soave–Redlich–Kwong (SRK) cubic equation of state (EOS) and a perturbed‐chain statistical associating fluid theory (PC‐SAFT) EOS. Two types of mixing rules were used with SRK EOS: The Wong–Sandler mixing rule and the linear combination of the Vidal and Michelsen mixing rules (LCVM), both of which incorporated the Bogdanic and Vidal activity coefficient model. The performance of these models was evaluated with atmospheric‐pressure and high‐pressure experimental SLE data obtained from literature. The basic SLE equation was solved for the equilibrium melting temperature instead of for the composition. The binary interaction parameters of SRK and PC‐SAFT EOS were estimated to best describe the experimental equilibrium behavior of 20 different polymer–solvent systems at atmospheric pressure and 31 other polymer–solvent systems at high pressure. A comparison with experimental data showed that SRK–LCVM agreed very well with the atmospheric SLE data and that PC‐SAFT EOS was more efficient in high‐pressure conditions. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011     

The solubility of CO2 in triethylene glycol monomethyl ether

The solubility of CO₂ in triethylene glycol monomethyl ether (TEGMME) has been measured at 40, 70 and 100°C at pressures up to 8.8 MPa. The results were correlated with the Peng-Robinson (1976) equation of state. The interaction parameters and Henry's constants were derived.     

Correlation of measured excess enthalpies of binary systems composed of n-alkane+1-alkanol

The excess enthalpies of the binary mixture composed of n-alkane (n-octane, n-nonane, n-decane) and 1-alkanol (ethanol, 1-propanol, 1-butanol) have been measured by using a flow-type isothermal microcalorimeter (model CSC 4400, Calorimetry Science Corp., USA) at 313.15 K under atmospheric pressure. The measured excess enthalpy data were correlated by the Redlich-Kister equation and the nonrandom lattice fluid with hydrogen bonding (NLFHB) equation of state. Hydrogen bonding type specific parameters were introduced in the NLF-HB equation of state framework, and the effects of those parameters were investigated for excess enthalpy calculations. With two adjustable temperature-dependent interaction parameters, the NLF-HB equation represents the excess enthalpies for nine binary systems qualitatively. This article is dedicated to Professor Chul Soo Lee in commemoration of his retirement from Department of Chemical and Biological Engineering of Korea University.     

Closure equations in the estimation of binary interaction parameters

Binary interaction parameters used in the UNIQUAC activity coefficient model are found to be dependent on each other and related by a linear relation termed as the closure equation. For a ternary system, six binary interaction parameters are related by one closure equation. Similarly for quaternary systems, three independent closure equations are obtained for the twelve binary interaction parameters and for quinary systems there are six closure equations for twenty parameters. Each closure equation consists of six parameters. The binary interaction parameters that do not satisfy the closure equations may lead to a less accurate prediction of liquid-liquid equilibria. In this work the binary interaction parameters have been estimated with and without closure equations for few ternary and quaternary systems. Parameters that satisfy the closure equations exhibit better root mean square deviation than those that do not satisfy the closure equations in most of the cases. A similar behavior is observed for NRTL model also.     

Vapor‐induced swelling of supported methacrylic and siloxane polymer films: Determination of interaction parameters

White light reflectance spectroscopy is applied to monitor vapor‐induced thickness changes of polymer films, supported on suitable silicon substrates. Assuming unidirectional swelling due to the constraining support, the equilibrium volume swelling of four methacrylic polymers and two siloxane‐based copolymers upon exposure to various activities of water, methanol, ethanol, and ethyl acetate vapor, at 30°C is evaluated. The deduced sorption isotherms were fitted to the Flory‐Huggins equation and interaction parameters, as well as solubility coefficients at infinite solute dilution, were deduced for each binary system. The relative sorption capacity of the different classes of polymers toward the four vapors are in line with the expected solubility interactions between solvent and solute. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2010     

Solubility of propylene in semicrystalline polypropylene

Gas solubilities and polymer swelling in propylene and semicrystalline polypropylene system at temperatures of 323.2 and 348.2 K and pressures up to propylene's vapor pressure were measured. Pressure, specific volume, and temperature (PVT) measurements of polypropylene were carried out at temperatures from 313 to 573 K and pressures up 200 MPa. Two kinds of polypropylenes, which had different stereoregularities, were used for both solubility and PVT measurements. The solubilities were correlated with the Sanchez–Lacombe equation of state (EOS) with temperature‐dependent binary interaction parameters to within 5% average relative percentage deviation. Swelling ratios estimated with Sanchez–Lacombe EOS coupled with optimized interaction parameters were 20% lower than the experimental values. © 2000 John Wiley & Sons, Inc. J Appl Polym Sci 79: 1134–1143, 2001     

The solubility of ethane in triethylene glycol monomethyl ether

The solubility of ethane in triethylene glycol monomethyl ether (TEGMME) has been measured at 40, 70 and 100°C at pressures up to 9.2 MPa. The solubility data obtained are compared with those of ethane in other physical solvents. The results were correlated with the Peng-Robinson (1976) equation of state and the interaction parameters were obtained. Henry's constants were also determined.     

Calculation of alcohol‐acetone‐cellulose acetate ternary phase diagram and their relevance to membrane formation

ABSTRACT Alcohol‐acetone‐cellulose acetate phase diagrams incorporated with methanol, ethanol, and isopropanol as nonsolvents are calculated according to a new form of the Flory–Huggins equation. Nonsolvent–cellulose acetate interaction parameters are measured by swelling experiments. Concentration‐dependent nonsolvent–solvent interaction parameters are obtained by vapor–liquid equilibrium and the Wilson equation. It is shown that alcohol is a week coagulant compared with water, and water > methanol > ethanol > isopropanol for cellulose acetate. The phase diagrams characteristic of acetone‐cellulose acetate combined with water, methanol, ethanol, and isopropanol as nonsolvents is different, which leads to the different morphological structure of a cellulose acetate membrane. The structure of a water coagulated membrane has large macrovoids from liquid–liquid phase separation. A methanol coagulated membrane has a honeycomb‐like structure from spinodal microphase separation. An ethanol or isopropanol coagulated membrane has a thicker, dense top layer from the delay time phase separation. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 80: 1650–1657, 2001     

Migration of substituted aromatic solvents into polyurethane/polystyrene semi‐interpenetrating polymer network

The molecular transport of substituted aromatic solvents through polyurethane/polystyrene (PU/PS, 50/50) semi interpenetrating polymer network has been investigated at 20, 40, and 60°C. Sorption–desorption–resorption–redesorption (S‐D‐RS‐RD) experiments were performed to determine the true value of transport coefficients. Sorption results are obtained by a gravimetric method and diffusion coefficients have been calculated using Fick's equation for the linear data points of time dependent sorption/resorption curves. It was observed that most of the systems follow the Fickian mode of transport. The first order kinetic equation was used to estimate the kinetic rate constant of sorption. Activation parameters for different transport processes were evaluated and the results were used to discuss the polymer–solvent interactions. The concentration profiles at different depths along the thickness of membranes and at different time intervals were computed using Fick's equation under appropriate boundary conditions. The rate of evaporation of liquids has been calculated for desorption and redesorption processes, and these results depend on the volatility of aromatic solvents. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 104: 378–390, 2007     

壳聚糖-聚乳酸接枝共聚物多孔支架制备

天然聚合物壳聚糖,生物可降解材料聚乳酸,都有着良好的生物相容性,在生物医学领域有着广泛的用途。但是,壳聚糖与聚乳酸各自的性能缺陷导致了这两者单独使用有着很大的局限性。为了改善这两者的缺点,可以利用将聚乳酸接枝共聚到壳聚糖主链上。这样既可以改善壳聚糖不易于加工的缺点,而壳聚糖本身碱性多糖的结构也可以中和乳酸降解过程中所产生的酸性。本文介绍了壳聚糖-聚乳酸接枝共聚体系的制备方法。     

二甲醚-甲醇体系二元交互参数的拟合与评价

本文通过化工模拟软件AspenPlus,液相采用NRTL模型,气相采用PR方程,对二甲醚-甲醇二元体系进行汽液平衡计算时涉及到的二元交互作用参数进行了研究。首先分别选用AspenPlus自带的三个数据库VLE—LIT、VLE—RK和VLE—HOC中二元交互参数进行计算,结果表明,选用数据库VLE—ILK和VLE—Hoc中模型参数时,计算值与实验值吻合较好,并且数据库vLE—RK的计算结果更好。其次利用文献实验数据拟合参数,进行气液平衡计算,与实验结果对比表明本文拟合参数最为适合,即对NRTL模型：a12=1．486,a21=-1．1496,b12=-28．06,b21=194．7,C12=0．0172;PR方程：k12=k21=-0．0605。