Isobaric vapor-liquid equilibria for methyl esters + butan-2-ol at different pressures

Vapor-liquid measurements for the mixtures of three methyl esters (ethanoate, propanoate, butanoate) and butan-2-ol were obtained at 74.66, 101.32 and 127.99 kPa in a small capacity still. All systems were found to be thermodynamically consistent and the maximum likelihood principle was chosen as the regression technique to determine the parameters of different available equations. Only the mixture methyl butanoate + butan-2-ol presented a minimum azeotrope which shifted toward concentrations richer in alcohol as working pressure increased. Experimental results were compared with prediction by UNIFAC and ASOG methods.     

Isobaric vapor–liquid equilibria for ethanol–water system containing different ionic liquids at atmospheric pressure

Isobaric vapor–liquid equilibrium (VLE) data for ethanol–water systems containing ionic liquids (ILs) 1-methyl-3-methylimidazolium dimethylphosphate ([MMIM][DMP]), 1-ethyl-3-methylimidazolium diethylphosphate ([EMIM][DEP]), 1-butyl-3-methylimidazolium bromide ([BMIM][Br]), 1-butyl-3-methylimidazolium chloride ([BMIM][Cl]) and 1-butyl-3-methylimidazolium hexafluorophosphate ([BMIM][PF₆]) at atmospheric pressure (101.32 kPa) were measured with a circulation still. The results showed that the VLE of ethanol–water systems in the presence of different ILs was obviously different from that of the IL-free system. All ILs studied showed a salting-out effect, which gave rise to a change of the relative volatility of ethanol, and even to an elimination of the azeotropic point. It was found that the salting-out effect followed the order of [BMIM][Cl] > [BMIM][Br] > [BMIM][PF₆] and [MMIM][DMP] > [EMIM][DEP], which was ascribed to the preferential solvation ability of the ions resulting from the dissociation of the IL.     

Isobaric vapour–liquid equilibria for binary mixtures of n-heptane with bromobenzene,chlorobenzene and fluorobenzene at atmospheric pressure

Vapour–liquid equilibria at atmospheric pressure for binary mixtures of n-heptane + bromobenzene, +chlorobenzene and +fluorobenzene have been determined. These have been shown to be thermodynamically consistent.     

Phase equilibria of methanol–triolein system at elevated temperature and pressure

The phase behavior of methnol–triolein system was determined experimentally at 6.0, 8.0 and 10.0 MPa in the temperature range of 353.2–463.2 K. The results demonstrated that the miscibility of the system was rather poor at low temperature, and the miscibility could be improved by increasing temperature. At a higher pressure, the miscibility was more sensitive to temperature as pressure was fixed. The critical temperature, critical pressure, and acentric factor of triolein were estimated and the experimental data were correlated using the Peng–Robinson equation of state. The calculated data agreed reasonably with the experimental results.     

Effect of 1,2-propanediol on the vapor-liquid equilibria of the ethyl acetate + ethanol system at 101.3 kPa

Vapor-liquid equilibrium (VLE) data for the system ethyl acetate + ethanol in the presence of 1,2-propanediol at concentrations of 0%, 20%, 30%, and 40% by weight were measured at 101.3 kPa. The experimental VLE data of the ternary system ethyl acetate + ethanol + 1,2-propanediol were correlated by the Margules, Wilson, NRTL, and UNIQUAC liquid models. The relative volativities of ethyl acetate with respect to ethanol were also determined. The results of the investigation indicate the disappearance of the binary azeotrope between ethyl acetate and ethanol at the solvent concentrations studied in this work.     

Isobaric vapour–liquid equilibria for binary mixtures of 1,2-dibromoethane with 1,2-dichloroethane,trichloromethane, and 1,1,2,2-tetrachloroethane at atmospheric pressure

Vapour–liquid equilibria at atmospheric pressure have been determined for binary mixtures of 1,2-dibromoethane + 1,2-dichloroethane, +trichloromethane, and +1,1,2,2-tetrachloroethane. These have been shown to be thermodynamically consistent.     

Isothermal vapor-liquid equilibria for the binary systems propylene-carbon dioxide,propylene-ethylene and propylene-ethane at high pressure

isothermal vapor-liquid equilibria for the binary systems propylene-carbon dioxide, propylene-ethylene and propylene-ethane have been measured at 283.15 and 298.15 K using a static method.The equilibrium data obtained have been correlated with the total-pressure method using both the Redlich-Kwong equation of state modified by Soave and the perturbation equation proposed by Gubbins and Twu. From normal probability plots of the residuals in the correlations versus the theoretical residuals in the normal distribution, the applicability of each of these two equations has been tested statistically.Furthermore, the fugacity coefficients calculated from the virial equation have been compared with those obtained from the correlations for the low-pressure regions.     

Isobaric (vapour+liquid) equilibria data for the binary systems (toluene+acetic acid) and (toluene+methyl ethyl ketone) at atmospheric pressure

Isobaric vapour–liquid equilibrium data have been measured for the binary systems toluene (1) + acetic acid (2) and toluene (1) + methyl ethyl ketone (2) at atmospheric pressure. An all-glass Fischer–Labodest-type apparatus, capable of handling pressures from 0.25 to 400 kPa and temperatures up to 523.15 K was used. The data were correlated by means of the NRTL, UNIQUAC, WILSON models and the applied UNIFAC model with satisfactory results; the relevant parameters are given and results were tested with regard to thermodynamic consistency using the methods of a modified Redlich–Kister and Herington equations.     

Electroinitiated oligomerization of methyl acrylate in methanol solution

The electroinitiated oligomerization of methyl acrylate in methanol solution in the presence of lithium acetate was studied. It was found that in this system the initiator is the methyl radical (obtained from anodic oxidation of acetate ion), and the major termination step is the abstraction of hydrogen radical from methanol by the growing oligomer chain. Eleven compounds were found to be formed in the reaction. A reaction sequence for their formation together with an electric balance for the reactions is given.     

Isobaric vapor liquid equilibria data for the binary system (glycidyl butyrate + acetone,glycidyl butyrate + carbon tetrachloride,glycidyl butyrate + chloroform) at atmospheric pressure 101 kPa

Isobaric vapor liquid equilibria (VLE) for the binary mixtures of glycidyl butyrate(1) + acetone(2), glycidyl butyrate(1) + carbon tetrachloride(2) and glycidyl butyrate(1) + chloroform(2) at 101 kPa were studied. The experimental data were satisfactorily correlated with the models of Wilson, NRTL and UNIQUAC activity coefficients. The activity coefficients for the equilibrium data were obtained by the nonlinear least square method. The average relative deviations between experimental temperatures and calculated temperatures by the Wilson, NRTL and UNIQUAC models were 0.16, 0.16, 0.23% for glycidyl butyrate(1) + chloroform( 2), 0.38, 0.12, 0.27% for glycidylbutyrate(1) + carbon tetrachloride(2), and 0.67, 0.13, 0.54% for glycidyl butyrate(1) + acetone(2). Azeotrope behavior was not found for these systems. The thermodynamic consistency of the correlations was checked by the Herrington’s area test.     

Isobaric vapor-liquid equilibria of acetone-propyl ether and isopropyl ether-propyl ether systems. Corroboration of no reverse volatility

Isobaric vapor - liquid equilibria were determined at 101.325 kPa for binary mixtures containing acetone + isopropyl ether, acetone + propyl ether and isopropyl ether + propyl ether using a dynamic still with vapor and liquid circulation. The azeotrope of the system acetone + isopropyl ether is in agreement with the literature value and none of the other systems shows an azeotrope.

The thermodynamic consistency of the experimental data was checked by Van Ness's test and Herington's criterion modified by Wisniak and they satisfied our data. The activity coefficients were correlated using the Wilson model and the UNIFAC prediction. In the final part of the work, an experiment for extractive distillation is described on a laboratory scale and the results confirmed that there is no reversal of volatility of this system.     

Thermal stability of copolymers of vinyl acetate and methyl acrylate

The thermal degradation of a series of copolymers of vinyl acetate and methyl acrylate and the two homopolymers poly(vinyl acetate) and poly(methyl acrylate) obtained using Ce(IV) as initiator has been investigated using differential thermal analysis (DTA) and thermogravimetry (TGA) in dynamic nitrogen. The kinetic parameters E, n, and A have been obtained following several methods of thermogravimetric analyses. The stability increases as the methyl acrylate content in the copolymer composition increases. The incorporation of 5 mol % of vinyl acetate in the copolymer produces a marked decrease in stability compared to the homopolymer poly(methyl acrylate). There is evidence for an intramolecular lactonization process in vinyl acetate—methyl acrylate copolymers.     

Semicontinuous seeded emulsion copolymerization of vinyl acetate and methyl acrylate

The semicontinuous seeded emulsion copolymerization of vinyl acetate and methyl acrylate was investigated. The effect of type of process (starved process versus semi-starved process), type of feed (neat monomer addition versus monomer emulsion addition), amount of seed initially charged in the reactor, and feed rate on the time evolution of the overall conversion, copolymer composition, and polymer particle size was analyzed. It was found that, in the case of the starved process, both monomers, but mainly vinyl acetate, accumulated in the reactor. The preferential accumulation of vinyle acetate resulted in a drift of the copolymer composition. Both monomers accumulation and copolymer composition drift were reduced by increasing the amount of seed initially charged in the reactor and by decreasing the feed rate. For the semi-starved process, it was found that a vinyl aceatate rich copolymer was formed when a low methyl acrylate feed was used, whereas a methyl acrylate rich copolymer was obtained at high methyl acrylate feed rates. For both starved process and semi-starved process, the total number of polymer particles, after an initial increase, reached a plateau value which was the same in all of the experiments carried out. These results were analyzed by means of a mathematical model developed for this system.     

Copolymerization of methyl acrylate and vinyl acetate catalyzed by ethylaluminium chlorides

The copolymerization of vinyl acetate with methyl acrylate in the presence of Et₂AlCl, Et_1.5AlCl_1.5, and Et₂AlCl-benzoyl peroxide systems has been investigated. The influence of monomer ratios and organoaluminium compound concentration on the copolymer yield and composition have been determined and discussed. The monomer sequences distribution has been studied by means of ¹³C-NMR. It was found that organoaluminium compounds in the studied systems catalyze not only the alternating copolymerization, but also the homopropagation of both monomers. An alternating copolymer was obtained in reactions carried out at ?78°C, when a large excess of vinyl acetate was used in the monomer feed.     

Surface modification of acrylate intraocular lenses with dielectric barrier discharge plasma at atmospheric pressure

Surface modification with dielectric barrier discharge (DBD) plasma was carried out at atmospheric pressure (argon as the discharge gas) to improve the biocompatibility of hydrophobic acrylate intraocular lens (IOL). Changes of the plasma-treated IOL surface in chemical composition, morphology and hydrophilicity were comprehensively evaluated by X-ray photoelectron spectroscopy (XPS), field emission scanning electron microscopy (FESEM), atomic force microscopy (AFM) and water contact angle (WCA) measurements. The surface biocompatibility of the untreated and plasma-treated IOLs was compared with the adhesion behavior of platelets, macrophages and lens epithelial cells (LECs) in vitro. After DBD plasma treatment, the hydrophilicity of the IOL surface was obviously improved. The changes in WCA with treatment extension may be attributed to both the introduction of oxygen or/and nitrogen-containing polar groups and the increase of surface roughness induced by plasma etching effect. The existence of low molecular weight oxidized material (LMWOM) was proved on the plasmatreated IOL which was caused by the chain scission effect of the plasma treatment. The plasma-treated IOLs resisted the adhesion of platelets and macrophages significantly. The LECs spreading and proliferation were postponed on the IOLs plasma-treated for more than 180 s, with a well maintained epithelial phenotype of LECs. The IOL biocompatibility was improved after the DBD plasma treatment. We speculate that slighter foreign-body reaction and later incidence of anterior capsule opacification (ACO) may be expected after implantation of the argon DBD plasma-treated IOL. Supported by the Zhejiang Natural Science Foundation of China (Grant No. 2004C23003)