Solvent dependent swelling behaviour of poly(<Emphasis Type="Italic">N</Emphasis>-vinylcaprolactam) and poly(<Emphasis Type="Italic">N</Emphasis>-vinylcaprolactam-<Emphasis Type="Italic">co</Emphasis>-itaconic acid) gels and determination of solubility parameters

Swelling behaviour of poly(N-vinylcaprolactam) (PVC) and poly(N-vinylcaprolactam-co-itaconic acid) (P(VC-co-IA)) gels was investigated in different solvents (water, ethanol, methanol, isopropyl alcohol (IPA), chloroform, toluene, acetone) and in binary solvent mixtures (ethanol/chloroform, ethanol/methanol, IPA/chloroform, ethanol/water, IPA/water). Gels were synthesised in ethanol by the free radical cross-linking polymerisation method at 60°C for 24 h in the presence of azo-bis(isobutyronitrile) and allyl methacrylate as the initiator and cross-linker, respectively. And also, ethanol/distilled water mixture (?_r = 4:1) was used as the synthesis medium to determine its effect on the swelling of gels. It was found that the presence of water in the synthesis medium significantly affected the equilibrium swelling value (ESV) and the swelling tendency of gels both in solvents and in solvent mixtures. All gels synthesised in ethanol showed the highest swelling in chloroform. The gels synthesised in the ethanol/water mixture displayed different swelling behaviour. In this case, while chloroform was still valid for maximum swelling of PVC, P(VC-co-IA) had the highest swelling in methanol. Solubility parameters of gels were predicted by the van Krevelen-Hoftyzer (VKH) and Hoy methods (group contribution methods) and theoretical calculations verified the experimental swelling order.     

Swelling behavior of chitosan hydrogels in ionic liquid-water binary systems

The swelling behavior of chitosan hydrogels in ionic liquid-water binary systems was studied using hydrophilic room-temperature ionic liquids (RTILs) to elucidate the swelling mechanism of chitosan hydrogels. No penetration of RTIL into a dry chitosan material was observed. Swelling was achieved by soaking in water-RTIL binary mixtures, with larger swelling observed at higher water contents. In one instance, the binary mixture was acidic and produced larger than expected swelling due to the dissociation of the amine groups in the chitosan. The equilibrium binary system content behavior of the chitosan hydrogels depended upon the amount of free water, which is a measure of the number of water molecules that do not interact with the ionic liquid. After evaporation of water, remnant RTIL remained in the chitosan network and hardness testing indicated a plasticization effect, suggesting that the RTIL molecularly mixed with the chitosan. Chitosan hydrogels containing only RTIL were prepared by dropping pure RTIL onto a fully preswollen hydrogel followed by water evaporation. This method may be a useful means for preparing air-stable swollen chitosan gels.     

Physical gelation of binary mixtures of hydrocarbons mediated by n-lauroyl-L-alanine and characterization of their thermal and mechanical properties

Fatty acid amides, such as n-lauroyl-L-alanine, gelate both aliphatic and aromatic hydrocarbon solvents efficiently. In addition this compound is found to gelate the binary solvent mixtures comprised of aromatic hydrocarbon, e.g., toluene and aliphatic hydrocarbons, e.g., n-heptane. Scanning electron microscopy and atomic force microscopy show that the fiber thickness of the gel assembly increases progressively in the binary mixture of n-heptane and toluene with increasing percentage of toluene. The self-assembly patterns of the gels in individual solvents, n-heptane and toluene, are however different. The toluene gel consists of predominantly one type of morphological species, while n-heptane gel has more than one species leading to the polymorphic nature of the gel. The n-heptane gel is thermally more stable than the toluene gel as evident from the measurement using differential scanning calorimetry. The thermal stability of the gels prepared in the binary mixture of n-heptane and toluene is dependent on the composition of solvent mixture. Rheology of the gels shows that they are shear-thinning material and show characteristic behavior of soft viscoelastic solid. For the gels prepared from binary solvent mixture of toluene and n-heptane, with incorporation of more toluene in the binary mixture, the gel becomes a more viscoelastic solid. The time sweep rheology experiment demonstrates that the gel made in n-heptane has faster gel formation kinetics than that prepared in toluene.     

Thermodynamic properties of biofuels: Heat capacities of binary mixtures containing ethanol and hydrocarbons up to 20 MPa and the pure compounds using a new flow calorimeter

Heat capacities are of great significance in the design of new processes and the improvement of existing ones in R&D in production plants as well as the adaptation of new products, in this case, biofuels to their use in a variety of engines and technical devices. An automated flow calorimeter has been developed for the accurate measurement of isobaric heat capacities for pure compounds and mixtures over the range (250 to 400) K and (0 to 20) MPa. In this paper, isobaric heat capacities for heptane, ethanol and the binary mixtures of ethanol with heptane and toluene are reported.     

Prediction of Excess Volumes and Excess Surface Tensions from Experimental Refractive Indices

Abstract

Refractive indices for the binary liquid mixtures: {hexane or heptane + ethanol}, {o-xylene + benzene} and {cyclohexane + benzene, toluene or hexane} were measured at 298.15 K. Excess refractive indices were calculated and fitted to a Redlich-Kister function. Using some mixture rules (Lorentz-Lorenz, Dale -Gladstone, Eykman, Oster, Arago-Biot and Newton), predictions for v^E have been made and compared with experimental data taken from the literature. Furthermore the Sugden equation has been used in two different ways for predicting excess surface tensions: the first one starting from densities and the other one from refractive indices. Results are plotted together with the literature data.     

STUDIES ON THE DYNAMIC COMPETITIVE ADSORPTION OF ORGANIC VAPORS ON THE ACTIVATED CARBON FIBERS ACTIVATED WITH PHOSPHORIC ACID

The dynamic competititve adsorption behaviors of different binary organic vapor mixtures on ACF-Ps under different operation conditons were investigated by gas chromatography in this paper,The studied mixtrues included benzene/toluene,toluene/xylene,benzene/isopropylbenzene ethly acetate/toluene and benzene/ethyl acetate.Experimental results show that various ACF-Ps,as with ACF-W,can remove both vapors in binary vapor mixtures with over 99% of removal efficiency before the breakthrough point of the more weakly adsorbed vapor,In dynamic competitive adsorption,the more weakly weakle adsorbed vapor noe only penetrates early,but also will be displaced and desorbed consequently by stronger adsorbate and therefore produces a rolling up in the breakthrough curve,The ACF-Ps prepared at different temperatuers have somewhat different adsorption selectivity,The feed concentration ratio of vapros,the length/diameter ratio and the thick of bed have effect on competitive adsorption.The competitive adsorption ability of a vapor is mainly related to its boiling point.Usually,the higher the boiling point ,the stronger the vapor adsorbed on ACF-P.     

近临界下HZSM-5催化的甲苯歧化反应

用高压观测池通过可视观测确定了苯、甲苯和对二甲苯等二元系及三元系的临界性质以及甲苯歧化反应混合物临界性质随着反应进程的变化规律；在此基础上，分别研究了近临界区以及高温下以HZSM-5为催化剂的甲苯歧化反应。结果发现，在近临界区甲苯歧化反应的对二甲苯选择性最高，随温度的升高甲苯转化率明显增加，对二甲苯选择性下降。高温下压力对对二甲苯选择性没有影响，转化率随压力升高而提高。     

Crosslinked Polystyrene Beads Modified with Sulfonyl Groups and Their Application in Aromatic/Aliphatic Hydrocarbons Separation

The separation of aromatic hydrocarbons from aromatic/aliphatic mixtures was investigated with cross- linked polystyrene（CPS） beads modified with sulfonyl groups. Three sulfonating agents, i.e. benzenesulfonyl chlo- ride（BsCl）, 4-toluene sulfonyl chloride（TsC1） and methanesulfonyl chloride（MsC1） were used to prepare sulfonyl CPS beads by Friedel-Crafts reaction. The CPS beads modified with BsC1 exhibited higher sulfonation rate than those modified with MsC1 and TsCI and obtained optimum selectivity in the experiments of toluene/n-heptane separation. Further separation tests with various other aromatic/aliphatic mixtures were carried out at an initial aromatic concen- tration of 13%（mass fraction） with the results showing that the modified beads have preferential selectivity for aro- matic hydrocarbons in all aromatic/aliphatic mixtures, and especially a separation factor of 8.21 and a swelling ratio of 30% for toluene/cyclohexane system. The thermal stability and regeneration test indicate that the used polystyrene beads can be recovered through heat-drying and reused effectively.     

A new specific metal ion chelated‐poly(N‐vinylimidazole) gel sorbents for albumin adsorption‐desorption

Poly(N‐vinylimidazole) (PVIm) hydrogels were prepared by γ‐irradiating binary mixtures of N‐vinylimidazole‐water in a ⁶⁰Co‐γ source having 4.5 kGy/h dose rate. These affinity gels having different swelling ratio of Cu(II)‐chelated, Co(II)‐chelated and plain PVIm in acetate buffer were used in the albumin adsorption studies. Bovine serum albumin (BSA) adsorption on these gels from aqueous solutions containing different amounts of BSA at different pH adjusted with acetate and phosphate buffer was investigated in batch reactors. The adsorption capacities of BSA on/in the gels were decreased dramatically by increasing the ionic strength (I) adjusting with NaCl. BSA adsorption capacities of the metal ion‐chelated gels were higher than the plain PVIm gel even if the swelling ratio of the metal ion‐chelated gels was very low comparing to the PVIm gel. The rigidity of the metal ion‐chelated gel is very high and it can be used for the column applications. More than 95% of BSA were desorbed in 3 h in the desorption medium containing KSCN for PVIm gel and EDTA for metal ion‐chelated gels. These results indicate that PVIm and metal ion‐chelated PVIm gels are very efficient to remove BSA and the different metal ion‐chelated PVIm gels show different affinity for BSA or biomolecules.     

Experimental and predicted excess molar volumes of the ternary system.

Summary Experimental excess molar volumes for the ternary system x₁MTBE+x₂1-propanol+(1-x₁-x₂) heptane and the three involved binary mixtures have been determined at 298.15 K and atmospheric pressure. Excess molar volumes were determined from the densities of the pure liquids and mixtures, using a DMA 4500 Anton Paar densimeter. The ternary mixture shows maximum values around the binary mixture MTBE+heptane and minimum values for the mixture MTBE+propanol. The ternary contribution to the excess molar volume is negative, with the exception of a range located around the rich compositions of 1-propanol. Several empirical equations predicting ternary mixture properties from experimental binary mixtures have been applied.     

Individual and simultaneous swelling of amphiphilic conetworks in water and n‐heptane

A series of amphiphilic conetworks of different compositions comprising poly(ethylene glycol) and poly(dimethylsiloxane) nanodomains were made, and their cocontinuity was characterized via separate swelling in water and n‐heptane and simultaneous swelling in water/n‐heptane mixtures. The extent and rate of swelling were determined and analyzed. The swelling of the cocontinuous hydrophilic poly(ethylene glycol) and hydrophobic poly(dimethylsiloxane) domains progressed independently of each other, and morphological changes, which occurred during swelling, influenced the rate of swelling. © 2006 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 44: 1474–1481, 2006     

长链不饱和脂肪酸甲酯的臭氧化反应

长链不饱和脂肪酸甲酯的臭氧化反应;选择性     

Liquid-liquid equilibria of (cyclohexane + acetonitrile + methylcyclohexane + toluene) and of {(acetonitrile + methylcyclohexane) + benzene or + toluene or + cyclohexane or + chlorobenzene} at 298.15 K

Tie-line results at 298.15 K and atmospheric pressure are reported for (cyclohexane + acetonitrile + methylcyclohexane + toluene) and for {(acetonitrile + methylcyclohexane) + benzene or + toluene or + cyclohexane or + chlorobenzene). The extended UNIQUAC and UNIQUAC equations are used to correlate binary vapour-liquid equilibria and mutual solubilities for 10 mixtures constituting the ternary mixtures and to predict the ternary and quaternary liquid-liquid equilibria by use of only binary parameters.     

Tuning aggregation of microemulsion droplets and silica nanoparticles using solvent mixtures

The effect of solvent on stability of water-in-oil microemulsions has been studied with AOT (sodium bis(2-ethylhexyl)sulfosuccinate) and different solvent mixtures of n-heptane, toluene and dodecane. Dynamic light scattering DLS was used to monitor the apparent diffusion coefficient D(A) and effective microemulsion droplet diameter on changing composition of the solvent. Interdroplet attractive interactions, as indicated by variations in D(A), can be tuned by formulation of appropriate solvent mixtures using heptane, toluene, and dodecane. In extreme cases, solvent mixtures can be used to induce phase transitions in the microemulsions. Aggregation and stability of model AOT-stabilized silica nanoparticles in different solvents were also investigated to explore further these solvent effects. For both systems the state of aggregation can be correlated with the effective molecular volume of the solvent V(mol)(eff) mixture.     

Preparation and Characterization of Poly(N‐Vinylpyrrolidone‐co‐Methacrylic Acid) Hydrogels

In this study, N‐vinylpyrrolidone (VP)/methacrylic acid (MAA) copolymers have been prepared at three different mole percents, the methacrylic acid composition being around 5, 10, 15%. MAA and VP monomer mixtures have been irradiated in ⁶⁰Co‐γ source at different irradiation doses and percent conversions have been determined gravimetrically. ～80% conversion of monomers into hydrogels were performed at 3.4 kGy irradiation dose. These hydrogels were swollen in distilled water at pH 4.0, 7.0, and 9.0. P(VP/MAA) hydrogel which contains 5% methacrylic acid showed the maximum % swelling at pH 9.0 in water. Diffusion of water was found to be of non‐Fickian character. Diffusion coefficients of water in P(VP/MAA) hydrogels were calculated. Initial swelling rates of P(VP/MAA) hydrogels increased with increasing pH and MAA content in hydrogels. Swelling kinetics of P(VP/MAA) hydrogels was found to be of second order. Thermal behavior of PMAA, PVP and P(VP/MAA) hydrogel were investigated by thermal analysis. P(VP/MAA) hydrogel gained new thermal properties and the temperature for maximum weight loss and temperature for half‐life of P(VP/MAA) hydrogel were determined.     

Adsorption of Uranyl Ions into Poly(Acrylamide‐co‐Acrylic Acid) Hydrogels Prepared by Gamma Irradiation

Acrylamide (AAm)/Acrylic Acid (AAc) copolymers have been prepared by gamma irradiation of binary mixtures at three different compositions where the acrylamide/acrylic acid mole ratios varied around 15, 20, and 30%. Threshold dose for 100% conversion of monomers into hydrogels was found to be 8.0 kGy. Poly(Acrylamide‐co‐Acrylic Acid) (poly(AAm‐co‐AAc)) hydrogels have been considered for the removal of uranyl ions from aqueous solutions. Swelling behavior of these hydrogels was determined in distilled water at different pH values and in aqueous solutions of uranyl ions. The results of swelling tests at pH 8.0 indicated that poly(AAm‐co‐AAc) hydrogel, containing 15% acrylamide showed maximum % swelling. Diffusion of water and aqueous solutions of uranyl ion into hydrogels was found to be non‐Fickian in character and their diffusion coefficients were calculated. The effect of pH, composition of hydrogel, and concentration of uranyl ions on the adsorption process were studied at room temperature. It was found that one gram of dry poly(AAm‐co‐AAc) hydrogel adsorbed 70–320 mg and 70–400 mg uranyl ions from aqueous solutions of uranyl nitrate and uranyl acetate in the initial concentration range of 50–1500 mg UO₂ ²⁺L^?, depending on the amount of AAc in the hydrogels, respectively. Adsorption isotherms were constructed for poly(AAm‐co‐AAc)–uranyl ion system indicating an S type of adsorption in the Giles classification system. It is concluded that crosslinked poly(AAm‐co‐AAc) hydrogels can be successfully used for the removal of uranyl ions from their aqueous solutions.     

Tricritical point induced by smectic ordering of a nematic gel

The authors study volume phase transitions of a nematic gel immersed in a liquid crystal (LC) solvent, which shows a second-order nematic-smectic A phase transition (NST). Combining Flory's elastic energy [Principles of Polymer Chemistry (Cornell University Press, Ithaca, 1953)] for a swelling of the gel with the McMillan model [Phys. Rev. A 4, 1238 (1971)] for smectic ordering, the authors calculate the equilibrium swelling of the gel and smectic order parameters as a function of temperature. The authors take into account an attractive interaction parameter c between the gel and LC solvents. On increasing the value of the coupling constant c, a second-order NST of the gel is changed to a first-order one and a continuous volume phase transition of the gel is changed to a discontinuous one. The authors find a tricritical point of the gel induced by smectic ordering.     

Modelling of the pervaporation of binary mixtures through moderately swelling,non-reacting membranes

The pervaporation of binary mixtures through moderately swelling membranes is analyzed as a solution—diffusion process, on the assumption that the diffusion coefficient of each permeant is an exponential function of both concentrations. A model is derived in which changes in selectivity and fluxes are related to major external conditions: the upstream mole fraction in the feed and the downstream total pressure of the pervaporate. This model leads to the computation of the pervaporation selectivity and the fluxes as a function of the parameters of the model. Numerical examples are given, relative to different shapes of curves for selectivity and fluxes. A flowsheet is given and allows, through the comparison with experimental results, the determination of the parameters of the model. Internal concentration profiles in the membrane may also be computed. In order to test the validity of this model, it has been applied to a set of experimental data for the pervaporation of hydrocarbon binary mixtures through nitrile—butadiene and styrene—butadiene copolymers.     

Viscosities of Binary Liquid Mixtures of Tetrachloroethylene with Some Aliphatic,Alicyclic and Substituted Aromatic Hydrocarbons

Abstract

Viscosities of binary mixtures of tetrachloroethylene with hexane, heptane, cyclohexane, methylcyclohexane, toluene, chlorobenzene, bromobenzene and nitrobenzene were measured at 303.15 K. The values of η^E are negative in all the systems except in tetrachloroethylene + bromobenzene system. An inversion in sign from positive to negative is observed in the system, tetrachloroethylene + bromobenzene. The viscosity data were analysed in terms of absolute reaction rate and free volume theories of liquid viscosity. Further, Grunberg and Nissan Parameter has also been evaluated.