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Ronald P Danner - One of the best experts on this subject based on the ideXlab platform.
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diffusion of solvents in poly vinyl acetate and partially and fully hydrolyzed poly vinyl alcohol
Polymer International, 2014Co-Authors: John M Zielinski, Mourad Hamedi, Ida M Balashova, Ronald P DannerAbstract:Diffusivities of methyl acetate, methanol and water in poly(vinyl acetate) and fully and partially hydrolyzed poly(vinyl alcohol) have been measured by capillary column inverse gas chromatography and/or gravimetric sorption. Data from the literature have been used when available for comparison. Overall the diffusivities show good consistency in terms of their temperature and concentration dependences. The Free-Volume Model has been applied to all the data with excellent results. In most cases the dramatic changes in diffusivities with temperature and concentration can be captured using only a few experimental data points and two regression parameters. This demonstrates that the Free-Volume theory is a valuable tool for the design of equipment for processing and devolatilization of polymer − solvent systems. © 2013 Society of Chemical Industry
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measuring and correlating diffusivity in polymer solvent systems using free volume theory
Fluid Phase Equilibria, 2014Co-Authors: Ronald P DannerAbstract:Abstract This paper provides a review of the measurement, data reduction, and correlation of diffusivities using the Free-Volume theory for polymer–solvent systems, particularly in the range of very low solvent concentration. The experimental methods discussed are inverse gas chromatography, gravimetric sorption, and pressure decay. The Free-Volume Model is described in terms of its potential and limitations for correlation and extrapolation of diffusion data. Data are given and analyzed for a number of systems including two of practical importance: solvents in poly(vinyl alcohol) and bisphenol-A in poly(vinyl chloride).
Christian Boned - One of the best experts on this subject based on the ideXlab platform.
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viscosity measurements and correlations of binary mixtures 1 1 1 2 tetrafluoroethane hfc 134a tetraethylene glycol dimethylether tegdme
Fluid Phase Equilibria, 2005Co-Authors: Matias Alfonso Monsalvo, Antoine Baylaucq, Patrick Reghem, Sergio E Quinonescisneros, Christian BonedAbstract:Abstract This paper reports viscosity data for the binary system1,1,1,2-tetrafluoroethane (HFC-134a), x1, +tetraethylene glycol dimethylether (TEGDME), 1 − x1. The measurements (200 data points) were obtained at various pressures (between 10 and 100 MPa) in the homogeneous liquid state from T = 293.15–373.15 K. The measurements have been carried out with a falling body viscometer for four molar fractions x1 = (0.28, 0.44, 0.63 and 0.88). The density values of this system were interpolated from previous results obtained at the laboratory. All of the available viscosity data, including pure HFC-134a and pure TEGDME (both previously studied at the laboratory), have been correlated using several viscosity Models (mixing rules, self-refrencing Model, hard-sphere theory, friction theory and free volume Model). The resulting Models are presented and discussed in this work.
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influence of the number of ch2ch2o groups on the viscosity of polyethylene glycol dimethyl ethers at high pressure
Fluid Phase Equilibria, 2004Co-Authors: Antoine Baylaucq, Christian Boned, Maria J P Comunas, Frederic Plantier, Josefa FernandezAbstract:Abstract This work reports new measurements of the viscosity of liquid diethylene glycol dimethylether (DEGDME) upto 100 MPa at eight temperatures ranging from 293.15 to 353.15 K. The measurements at atmospheric pressure have been performed with an Ubbelohde-type glass capillary tube viscometer with an uncertainty of ±1%. At pressures upto 100 MPa the viscosity was determined with a falling body viscometer with an uncertainty of ±2%. Using previous polyalkylene glycol dimethylether viscosity and density data (Triethylene glycol dimethyl ether and tetraethylene glycol dimethyl ether) obtained at the laboratory, present measurements were used to study the dependence of the viscosity and of the molecular parameters of hard-sphere scheme and Free-Volume Model on the number of CH2CH2O groups.
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the effect of stereoisomerism on dynamic viscosity a study of cis decalin and trans decalin versus pressure and temperature
Physical Chemistry Chemical Physics, 2003Co-Authors: Claus K Zebergmikkelsen, Antoine Baylaucq, Mohammed Barrouhou, Christian BonedAbstract:Decahydronaphthalene (decalin) exists in two stereoisomeric molecular configurations, a cis and a trans configuration. The cis and trans isomers have different physical properties. In this work, a study of the stereoisomeric effect on the dynamic viscosity (and density) versus pressure and temperature has been carried out up to 100 MPa in the temperature range 293.15 K to 353.15 K. The viscosity of cis-decalin is higher than the one of trans-decalin in the considered temperature and pressure ranges due to the twisted structure of cis-decalin compared to the relative more symmetric and rigid structure of trans-decalin. Further, the density of cis-decalin is around 3% higher than for trans-decalin. The measured data have been used in order to perform an analysis of the stereoisomeric effects using recently developed viscosity approaches with a physical and theoretical background. For the hard-sphere scheme it has been found that the roughness factor is related to the specific structure of the stereoisomeric molecules, whereas the same hard-core volume is obtained for cis-decalin and trans-decalin. In the case of the Free-Volume Model, the term arising from the energy barrier, which the molecules have to cross in order to diffuse, is approximately the same for cis-decalin and trans-decalin, but the characteristic molecular length and the molecular overlap of the free volume are different, and strongly related to the structural configuration of the stereoisomeric decalin molecules.
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a new free volume Model for dynamic viscosity and density of dense fluids versus pressure and temperature
Physics and Chemistry of Liquids, 2001Co-Authors: A. Allal, M Mohaouchane, Christian BonedAbstract:Abstract This article presents a Model based on the free volume concept, which describes the variations of dynamic viscosity and density versus temperature and pressure for the dense fluids (density > 200 kg · m−3). This Model involves 6 constants for each pure compound: 3 for viscosity and 4 for density (1 constant is common to both quantities). Moreover if the viscosity and the density are known at a pressure and temperature of reference, it is sufficient to use 4 constants per pure compound. If the density is assumed to be known the Model fits the viscosity data with an average absolute deviation of 3.8% for 3297 data corresponding to 41 very different pure compounds (alkanes, alkylbenzenes, cycloalkanes, alcohols, carbon dioxide, refrigerants). If the pressure is lower than 110MPa the average absolute deviation is 2.8% for viscosity (2977 points). The Model gives also good results for water (3.6%). If the density is unknown, for pressures lower than 110MPa the Model represents viscosity with an averag...
R Krauserehberg - One of the best experts on this subject based on the ideXlab platform.
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free volume investigation of imidazolium ionic liquids from positron lifetime spectroscopy
Fluid Phase Equilibria, 2014Co-Authors: Dana Bejan, R KrauserehbergAbstract:Abstract In this work, relationships between the free volume and various fundamental physical properties (density, surface tension and transport properties) of ionic liquids were investigated. Two imidazolium ionic liquids 1-butyl-3-methylimidazolium tris(pentafluoroethyl)trifluoro phosphate ([C4MIM][FAP]) and 1-butyl-3-methylimidazolium bis[bis(pentafluoroethyl)phosphinyl]imide ([C4MIM][FPI]) were measured by positron annihilation lifetime spectroscopy (PALS). Changes of the ortho-positronium lifetime (o-Ps) with different states (amorphous and crystalline) were depicted as completely as possible. The mean local free (hole) volume was calculated from the o-Ps lifetime in amorphous state for the samples. Comparison between and specific volume obtained from the temperature dependent mass density gave the specific hole densities Nf and the occupied volumes Vocc. Thermal expansion of hole volume was compared with molecular volume VM of [C4MIM][FAP] and [C4MIM][FPI] as well as five other ionic liquids from our previous works, a monotonically increasing correlation between the two quantities was displayed. Hole volume of [C4MIM][FAP] sample from PALS experiment was compared with the result from surface tension according to Furth hole theory, good agreement exhibited. The free volume obtained from this work was applied to Cohen–Turnbull fitting of viscosity for [C4MIM][FPI] sample. The influence of the free volume to transport properties was investigated by the comparison of /VM with the viscosity and conductivity for various ionic liquids. Correlation between the free volume and the molecular volume of ionic liquids was explained by a schematic free volume Model.
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free volume of an epoxy resin and its relation to structural relaxation evidence from positron lifetime and pressure volume temperature experiments
Physical Review E, 2006Co-Authors: G Dlubek, R Krauserehberg, E M Hassan, Jurgen PionteckAbstract:From positron annihilation lifetime spectroscopy analyzed with the new routine LT9.0 and pressure-volume-temperature experiments analyzed employing the equation of state (EOS) Simha-Somcynsky lattice-hole theory (SS EOS) the microstructure of the free volume and its temperature dependence of an oligomeric epoxy resin (ER6, ${M}_{n}\ensuremath{\approx}1750\phantom{\rule{0.3em}{0ex}}\mathrm{g}∕\mathrm{mol}$, ${T}_{g}=332\phantom{\rule{0.3em}{0ex}}\mathrm{K}$) of diglycidyl ether of bisphenol-$A$ (DGEBA) have been examined and characterized by the hole Free-Volume fraction $h$, the specific free and occupied volumes ${V}_{f}=hV$ and ${V}_{\mathrm{occ}}=(1\ensuremath{-}h)V$, and the size distribution (mean, $⟨{\ensuremath{\nu}}_{h}⟩$, and mean dispersion, ${\ensuremath{\sigma}}_{h}$) and the mean density ${N}_{h}^{\ensuremath{'}}={V}_{f}∕⟨{\ensuremath{\nu}}_{h}⟩$, of subnanometer-size holes. The results are compared with those from a previous work [G. Dlubek et al., Phys. Rev. E 73, 031803 (2006)] on a monomeric liquid of the same resin (ER1, ${M}_{n}\ensuremath{\approx}380\phantom{\rule{0.3em}{0ex}}\mathrm{g}∕\mathrm{mol}$, ${T}_{g}=255\phantom{\rule{0.3em}{0ex}}\mathrm{K}$). In the glassy state ER6 shows the same hole sizes as ER1 but a higher ${V}_{f}$ and ${N}_{h}^{\ensuremath{'}}$. In the liquid ${V}_{f}$, $⟨{\ensuremath{\nu}}_{h}⟩$, $d{V}_{f}∕dT$, and $d{V}_{f}∕dP$ are smaller for ER6. The reported dielectric $\ensuremath{\alpha}$ relaxation time $\ensuremath{\tau}$ shows certain deviations from the Free-Volume Model which are larger for ER6 than for ER1. This behavior correlates with the SS EOS, which shows that the unit of the SS lattice is more heavy and bulky and therefore the chain is less flexible for ER6 than for ER1. The Free-Volume fraction $h$ in the liquid can be described by the Schottky equation $h\ensuremath{\propto}\mathrm{exp}(\ensuremath{-}{H}_{h}∕{k}_{B}T)$, where ${H}_{h}=7.8$--$6.4\phantom{\rule{0.3em}{0ex}}\mathrm{kJ}∕\mathrm{mol}$ is the vacancy formation enthalpy, which opens a different way for the extrapolation of the equilibrium part of the free volume. The extrapolated $h$ decreases gradually below ${T}_{g}$ and becomes zero only when $0\phantom{\rule{0.3em}{0ex}}\mathrm{K}$ is reached. This behavior means that no singularity would appear in the relaxation time at temperatures above $0\phantom{\rule{0.3em}{0ex}}\mathrm{K}$. To quantify the degree to which volume and thermal energy govern the structural dynamics, the ratio of the activation enthalpies ${E}_{i}=R[(d\phantom{\rule{0.2em}{0ex}}\mathrm{ln}\phantom{\rule{0.2em}{0ex}}\ensuremath{\tau}∕d{T}^{\ensuremath{-}1}){]}_{i}$, at constant volume $V$ and constant pressure $P({E}_{V}∕{E}_{P})$, is frequently determined. We present arguments for necessity to substitute ${E}_{V}$ by ${E}_{Vf}$, the activation enthalpy at constant (hole) free volume, and show that ${E}_{Vf}∕{E}_{P}$ changes as expected: it increases with increasing free volume, i.e., with increasing temperature, decreasing pressure, and decreasing molecular weight. ${E}_{Vf}∕{E}_{P}$ exhibits smaller values than ${E}_{V}∕{E}_{P}$, which leads to the general inference that the free volume plays a larger role in dynamics than concluded from ${E}_{V}∕{E}_{P}$. The same conclusion is obtained when scaling $\ensuremath{\tau}$ to ${T}^{\ensuremath{-}1}{V}_{f}^{\ensuremath{-}\ensuremath{\gamma}}$ instead of to ${T}^{\ensuremath{-}1}{V}^{\ensuremath{-}\ensuremath{\gamma}}$, where both $\ensuremath{\gamma}$'s are material constants.
Sekh Mahiuddin - One of the best experts on this subject based on the ideXlab platform.
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electrical conductivity viscosity and molar volume of potassium nitrate sodium nitrate in cadmium nitrate tetrahydrate melt
Australian Journal of Chemistry, 1998Co-Authors: Gautam Kalita, Nashiour Rohman, Sekh MahiuddinAbstract:The electrical conductivities, viscosities and molar volumes of the 0·3[xKNO3+(1 – x)NaNO3]+ 0·7Cd(NO3)2.4·4H2O systems were measured as functions of temperature (293·15 ≤ T/K ≤ 363·15) and composition (x = 0·0 to 1·0 mole fraction). The temperature dependence of the electrical conductivity and viscosity was non-Arrhenius in nature and has been analysed by using the Vogel–Tammann–Fulcher (VTF) equation. Both conductivity and viscosity vary non-linearly with the molar volume and have been explained by using VTF-type equations based on the free volume Model. In the present system the molar volume and the intrinsic volume are additive. A significant mixed alkali effect has been observed in the normalized electrical conductivity and viscosity and in the electrical conductivity at the isofluidity condition. The variation of the electrical conductivity is governed by the mobility of the potassium ions. The onset of the mixed alkali effect has been explained by the anion polarization Model.
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electrical conductivity viscosity and molar volume of potassium nitrate lithium nitrate cadmium nitrate tetrahydrate melt systems
Journal of Chemical & Engineering Data, 1997Co-Authors: Gautam Kalita, Nashiour Rohman, Sekh MahiuddinAbstract:Densities, viscosities, and electrical conductivity of potassium nitrate + lithium nitrate + cadmium nitrate tetrahydrate melt systems were measured as functions of temperature (≈292.15 ≤ T/K ≤ 363.15) and at various compositions x. The temperature dependence of viscosity and conductivity has been described by the Vogel−Tammann−Fulcher (VTF) equation. Molar volume data were fitted to an equation similar to the VTF equation based on the free volume Model. Viscosity isotherms, unlike electrical conductivity, exhibit both negative as well as positive deviation from linearity as a function of composition. Mixed alkali effect in electrical conductivity has been observed under the isoviscosity condition. The onset of the mixed alkali effect has been explained in terms of the anion polarization Model and complex ion of cadmium.
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mixed alkali effect in sodium thiocyanate potassium thiocyanate acetamide melt systems
Canadian Journal of Chemistry, 1996Co-Authors: Sekh MahiuddinAbstract:Electrical conductivity and molar volume of the 0.25[xNaSCN + (1 −x)KSCN] + 0.75CH3CONH2 systems were measured as functions of temperature and composition (x = 0.0 – 1.0 mol fraction). Temperature dependence of the electrical conductivity was non-Arrhenius in nature and has been analysed by using the Vogel–Tammann–Fulcher (VTF) equation. Molar volume data were fitted to an equation similar to the VTF equation based on the free volume Model. Molar volumes and intrinsic volumes were found to be additive in nature. Electrical conductivity isotherms deviate from linearity in different fashion for different temperature regions. The onset of the mixed alkali effect is governed by the anion polarization effect, by a contribution of the auto-dissociated molten acetamide, and by polymeric-type solvated ions. Key words: electrical conductivity, sodium thiocyanate, potassium thiocyanate, acetamide, mixed alkali effect.
Douglass S Kalika - One of the best experts on this subject based on the ideXlab platform.
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effect of copolymer composition temperature and carbon dioxide fugacity on pure and mixed gas permeability in poly ethylene glycol based materials free volume interpretation
Journal of Membrane Science, 2007Co-Authors: Sumod Kalakkunnath, Douglass S KalikaAbstract:Abstract Network copolymers, prepared by photopolymerizing poly(ethylene glycol) diacrylate (PEGDA: CH 2 CHCOO(CH 2 CH 2 O) 14 OCCH CH 2 ) and poly(ethylene glycol) methyl ether acrylate (PEGMEA: CH 2 CHCO(OCH 2 CH 2 ) 8 OCH 3 ), have been studied for mixed-gas CO 2 /H 2 and CO 2 /CH 4 separations. Gas separation properties in the networks are sensitive to copolymer composition, temperature, and carbon dioxide fugacity in the feed. In conventional approaches, the effect of temperature can be described by the Arrhenius equation, while the influence of copolymer composition and fugacity can only be described empirically; the corresponding Models require a large number of adjustable parameters. However, as shown here, the three factors influencing gas transport correlate well with free volume, and a simplified free volume Model with only two adjustable parameters can satisfactorily describe the effects of copolymer composition, temperature, and CO 2 fugacity on pure- and mixed-gas transport properties. Copolymer composition and temperature can be directly related to the fractional free volume, while CO 2 fugacity of the feed can be correlated with free volume via the glass transition temperature of the polymer–gas mixture, which is computed using Chow's Model.
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transport and structural characteristics of crosslinked poly ethylene oxide rubbers
Journal of Membrane Science, 2006Co-Authors: Haiqing Lin, Sumod Kalakkunnath, Benny D Freeman, Elizabeth M Van Wagner, J S Swinnea, Steven J Pas, Anita J Hill, Douglass S KalikaAbstract:Abstract Three series of crosslinked poly(ethylene oxide) rubbers have been prepared by photopolymerization of prepolymer solutions containing: (1) poly(ethylene glycol) diacrylate (PEGDA) and H2O, (2) PEGDA and poly(ethylene glycol) methyl ether acrylate (PEGMEA), and (3) PEGDA and poly(ethylene glycol) acrylate (PEGA). All of these polymers have similar chemical composition (approximately 82 wt.% ethylene oxide), but the crosslink density and the content and chemistry of chain end groups are different. The effect of chain end groups and crosslink density on mass density, glass transition temperature (Tg), free volume, and H2, N2, CH4 and CO2 transport properties of the polymers was determined. The effect of temperature on gas permeability and solubility was also investigated. Many of the samples were amorphous. However, samples with high concentrations of PEGMEA could crystallize, and the formation of crystalline regions significantly decreased permeability. A generalized free volume Model was used to interpret the effect of crosslink density and chain end groups on gas permeability and diffusivity, where free volume was characterized using two techniques: (1) density and group contribution theory, and (2) positron annihilation lifetime spectroscopy. Finally, the potential application of these materials for CO2/light gas separations was explored.
