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Probing the Structure of Liquids with 129Xe NMR Spectroscopy: n-Alkanes, Cycloa...
Morgado, Pedro; Bonifácio, Rui; Martins, Luís F. G.; Filipe, Eduardo J. M.The liquid organization of linear, branched, and cyclic alkanes was studied using atomic 129Xe as a NMR probe. 129Xe chemical shifts have been experimentally determined for xenon dissolved in a total of 21 alkanes. In order to allow the comparison of the different solvents at similar thermodynamic conditions, the measurements were performed over a wide range of temperatures, from the melting point of the solven...
Liquid Mixtures Involving Hydrogenated and Fluorinated Chains: (p, ρ, T, x) Sur...
Duarte, Pedro; Silva, Marcelo; Rodrigues, Djêide; Morgado, Pedro; Martins, Luís F. G.; Filipe, Eduardo J. M.The effect of mixing hydrogenated and fluorinated molecules that simultaneously interact through strong hydrogen bonding was investigated: (ethanol + 2,2,2-trifluoroethanol) binary mixtures were studied both experimentally and by computer simulation. This mixture displays a very complex behavior when compared with mixtures of hydrogenated alcohols and mixtures of alkanes and perfluoroalkanes. The excess volumes...
Viscosity of liquid systems involving hydrogenated and fluorinated substances: ...
Morgado, Pedro; Black, Jana; Lewis, J. Ben; Iacovells, Christopher R.; McCabe, Clare; Martins, Luís F. G.; Filipe, Eduardo J. M.The viscosity of (hexane + perfluorohexane) mixtures has been measured at 298 K, 303 K and 308 K, over the whole composition range. The results show large negative deviations from the arithmetic mean of the viscosities of the pure components, reaching −17% at x(perfluorohexane) = 0.7. To obtain molecular level insight into the behaviour of the system, all-atom molecular dynamics simulations have been performed ...
Diffusion coefficients of 2,2,2-trifluoroethanol/water mixtures
Pereira, Luís A. M.; Ramalho, João P. P.; Carvalho, Alfredo J. P.; Morgado, Pedro; Filipe, Eduardo J. M.; Martins, Luís F. G.Aqueous mixtures of 2,2,2-trifluoroethanol have received significant attention in the last years because their applications, such as working fluid in Rankine cycle thermal engines or as solvent in studies of protein stability (protein folding). From the fundamental point of view, fluoroalcohols have an amphyphile character, due to the simultaneous presence of a hydrophobic (and alkane-phobic) fluorinated surfac...
Excess Thermodynamic Properties of Mixtures Involving Xenon and Light Alkanes: ...
Martins, Luís F. G.; Palace Carvalho, Alfredo J.; Prates Ramalho, João P.; Filipe, Eduardo J. M.As a natural extension of a previous work, excess molar enthalpies and excess molar volumes as a function of composition in a wide range of temperatures have been obtained for binary mixtures of xenon with ethane, propane, and n-butane by Monte Carlo computer simulation. Xenon was modeled by a simple spherical Lennard-Jones potential, and the TraPPE-UA force field was used to describe the n-alkanes. One of the ...
Systems involving hydrogenated and fluorinated chains: Volumetric properties of...
Morgado, Pedro; Lewis, J. Ben; Laginhas, Carlos M. C.; Martins, Luis F. G.; McCabe, Clare; Blas, Felipe J.; Filipe, Eduardo J. M.As part of a combined experimental and theoretical study of the thermodynamic properties of perfluoroalkylalkanes (PFAAs), the liquid density of perfluorobutylpentane (F4H5), perfluorobutylhexane (F4H6), and perfluorobutyloctane (F4H8) was measured as a function of temperature from 278.15 to 353.15 K and from atmospheric pressure to 70 MPa. The liquid densities of n-perfluoropentane, n-perfluorohexane, n-perflu...
Viscosity of Liquid Perfluoroalkanes and Perfluoroalkylalkane Surfactants
Morgado, Pedro; Laginhas, Carlos M. C.; Lewis, J. Ben; McCabe, Clare; Martins, Luís F. G.; Filipe, Eduardo J. M.As part of a systematic study of the thermophysical properties of two important classes of fluorinated organic compounds (perfluoroalkanes and perfluoroalkylalkanes), viscosity measurements of four n-perfluoroalkanes and five perfluoroalkylalkanes have been carried out at atmospheric pressure and over a wide range of temperatures (278–353 K). From the experimental results the contribution to the viscosity from ...
On the Behaviour of Solutions of Xenon in Liquid Cycloalkanes: Solubility of Xe...
Bonifácio, Rui P. M. F.; Filipe, Eduardo J. M.; dos Ramos, M. Carolina; Martins, Luís F. G.The solubility of xenon in liquid cyclopentane has been studied experimentally and theoretically. Measurements of the solubility of xenon in liquid cyclopentane are reported as a function of temperature from 254.60Kto 313.66 K. The imprecision of the experimental data is less than 0.3%. The thermodynamic functions of solvation of xenon in cyclopentane, such as the standard Gibbs energy, enthalpy, entropy and he...
On the Behavior of Solutions of Xenon in Liquid n-Alkanes: Solubility of Xenon ...
Bonifácio, Rui P. M. F.; Martins, Luís F. G.; McCabe, Clare; Filipe, Eduardo J. M.The solubility of xenon in liquid n-pentane and n-hexane has been studied experimentally, theoretically, and by computer simulation. Measurements of the solubility are reported for xenon + n-pentane as a function of temperature from 254 to 305 K. The uncertainty in the experimental data is less than 0.15%. The thermodynamic functions of solvation such as the standard Gibbs energy, enthalpy, and entropy of solva...
Excess Thermodynamics of Mixtures Involving Xenon and Light Linear Alkanes by C...
Palace Carvalho, Alfredo J.; Prates Ramalho, João P.; Martins, Luís F. G.Excess molar enthalpies and excess molar volumes as a function of composition for liquid mixtures of xenon + ethane (at 161.40 K), xenon + propane (at 161.40 K) and xenon + n-butane (at 182.34 K) have been obtained by Monte Carlo computer simulations and compared with available experimental data. Simulation conditions were chosen to closely match those of the corresponding experimental results. The TraPPE-UA fo...
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