Mark McHugh | Virginia Commonwealth University (original) (raw)
Papers by Mark McHugh
Rocket propellants are subjected to extreme thermodynamic conditions in high-performance liquid r... more Rocket propellants are subjected to extreme thermodynamic conditions in high-performance liquid rocket engines, with temperatures in excess of 700 K and pressures nearing 100 MPa. Knowledge of the fuel viscosity is crucial for modeling the performance of liquid rocket engines utilizing rocket grade kerosene rocket propellant 1 (RP-1) or RP-2. The present study reports the viscosity of two RP-2 fuel samples at temperatures from 298 to 573 K and pressures up to 100 MPa. A high-temperature, highpressure (HTHP), variable-volume, close-clearance, windowed, rolling-ball viscometer is used to measure the viscosity based on terminal velocity and RP-2 density. To facilitate the use of the RP-2 viscosity data with computational fluid dynamics (CFD) and other analytical models, these data are modeled with the free volume theory (FVT), with an empirical temperature/pressure-dependent correlation and with a modified form of the Vogel−Fulcher−Tammann (VFT) equation.
Public reporting burden for this collection of information is estimated to average 1 hour per res... more Public reporting burden for this collection of information is estimated to average 1 hour per response, including the time for reviewing instructions, searching existing data sources, gathering and maintaining the data needed, and completing and reviewing this collection of information. Send comments regarding this burden estimate or any other aspect of this collection of information, including suggestions for reducing this burden to Washington Headquarters Services, Directorate for Information Operations and Reports,
International Journal of Pharmaceutics, 2014
This paper describes the synthesis of H 2 O 2-H 2 O filled poly(methyl methacrylate) (PMMA) micro... more This paper describes the synthesis of H 2 O 2-H 2 O filled poly(methyl methacrylate) (PMMA) microcapsules as potential candidates for controlled O 2 delivery. The microcapsules are prepared by a water-in-oil solvent emulsion and evaporation method. The results of this study describe the effect of process parameters on the characteristics of the microcapsules and on their in vitro performance. The size of the microcapsules, as determined from scanning electron microscopy, ranges from ~5 to 30 µm and the size distribution is narrow. The microcapsules exhibit an internal morphology with entrapped H 2 O 2-H 2 O droplets randomly distributed in the PMMA continuous phase. In vitro release studies of 4.5 wt% H 2 O 2 loaded microcapsules show that ~70% of the H 2 O 2 releases in 24 hours. This corresponds to a total O 2 production of ~12 cc per gram of dry microcapsules. Shelf-life studies show that the microcapsules retain ~84 wt% of the initially loaded H 2 O 2 after nine months storage at 2-to-8 °C, which is an attractive feature for clinical applications.
The Journal of Supercritical Fluids, 2013
Chemical Engineering & Technology, 2000
This paper was also published in German in Chem. Ing. Tech. 71 (1999) No. 7, pp. 729±732.
Industrial & Engineering Chemistry Research, 2015
This study reports the high-temperature, high-pressure density data for propane, squalane, and th... more This study reports the high-temperature, high-pressure density data for propane, squalane, and their binary mixtures for five compositions at temperatures to 520 K and pressures to 260 MPa. The density measurements are obtained with a floating-piston, variable-volume, high-pressure view cell. From the density data, the isothermal and isobaric excess molar volumes upon mixing are computed. For the mixture compositions studied here, the excess volume is mostly negative, showing a minimum at 0.6550 mole fraction of propane and becomes less negative as the propane concentration increases. The perturbedchain statistical associating fluid theory (PC-SAFT) equation of state (EoS) provides good representation for the experimental data. A mean absolute percent deviation (δ) of 1.4% is obtained with the PC-SAFT EoS when using propane and squalane pure component parameters fit to density data at high-temperature, high-pressure conditions.
The Journal of Chemical Thermodynamics, 2015
ABSTRACT Binary mixture density data are reported for propane (C3) with n-decane (C10) and with n... more ABSTRACT Binary mixture density data are reported for propane (C3) with n-decane (C10) and with n-eicosane (C20) at T = (320 to 525) K and pressures to 265 MPa. The (C3 + C10) mixture density data are in good agreement with available literature data to 70 MPa, which is the maximum reported literature pressure. There are no available binary mixture density data to compare to the (C3 + C20) mixture density data reported in the present study. The mixture density data are correlated with the Tait equation to facilitate interpolation of the data at different experimental conditions. Equations of state that are suitable for reservoir simulations are used to model the reported data. These models include the Peng–Robinson equation of state (PREoS), a volume-translated PREoS fit to high temperature, high pressure (HTHP) pure component density data, the PC-SAFT EoS, and modifications of the PC-SAFT EoS developed for better representation of HTHP data. The models give superior density predictions for (C3 + C10) mixtures compared to (C3 + C20) mixtures.
ABSTRACT The necessity of exploring ultradeep reservoirs requires the accurate prediction of hydr... more ABSTRACT The necessity of exploring ultradeep reservoirs requires the accurate prediction of hydrocarbon density data at extreme temperatures and pressures. In this study, three equations of state (EoS) models, Peng-Robinson (PR), high-temperature high-pressure volume-translated PR (HTHP VT-PR), and perturbed-chain statistical associating fluid theory (PC-SAFT) EoS are used to predict the density data for hydrocarbons in ultradeep reservoirs at temperatures to 523 K and pressures to 275 MPa. The calculated values are compared with experimental data. The results show that the HTHP VT-PR EoS and PC-SAFT EoS always perform better than the regular PR EoS for all the investigated hydrocarbons.
Fluid Phase Equilibria, 2014
ABSTRACT Experimental phase behavior data are reported for three hyperbranched polyester polymers... more ABSTRACT Experimental phase behavior data are reported for three hyperbranched polyester polymers, Boltorn H20 (B-H20), Boltorn H2004 (B-H2004), and Boltorn U3000 (B-U3000) in supercritical ethane, propane, propylene, CO2, and dimethyl ether (DME) at temperatures to 450 K and pressures to 200 MPa. B-H20 has 100% hydroxyl terminal groups, B-H2004 has 60% saturated C6 and C8 hydrocarbon terminal groups, and B-U3000 has 90% unsaturated C16 and C18 hydrocarbon terminal groups. Cloud point, liquid–vapor, and liquid–liquid–vapor phase transitions are measured with a high-pressure, variable-volume, view cell for each Boltorn polymer at ∼5 wt% in solution. B-H20, with 100% hydroxyl terminal groups, only dissolves in DME, which is expected to hydrogen bond to the polymer hydroxyl groups. At the other extreme, B-U3000, with long chain, nonpolar hydrocarbon terminal groups, is significantly more soluble in nonpolar ethane and propane compared to propylene, CO2, or DME.
The Journal of Physical Chemistry B, 2013
The cis and trans conformation of a branched cyclic hydrocarbon affects the packing and, hence, t... more The cis and trans conformation of a branched cyclic hydrocarbon affects the packing and, hence, the density, exhibited by that compound. Reported here are density data for branched cyclohexane (C6) compounds including methylcyclohexane, ethylcyclohexane (ethylcC6), cis-1,2-dimethylcyclohexane (cis-1,2), cis-1,4-dimethylcyclohexane (cis-1,4), and trans-1,4-dimethylcyclohexane (trans-1,4) determined at temperatures up to 525 K and pressures up to 275 MPa. Of the four branched C6 isomers, cis-1,2 exhibits the largest densities and the smallest densities are exhibited by trans-1,4. The densities are modeled with the Peng-Robinson (PR) equation of state (EoS), the high-temperature, high-pressure, volume-translated (HTHP VT) PREoS, and the perturbed chain, statistical associating fluid theory (PC-SAFT) EoS. Model calculations highlight the capability of these equations to account for the different densities observed for the four isomers investigated in this study. The HTHP VT-PREoS provides modest improvements over the PREoS, but neither cubic EoS is capable of accounting for the effect of isomer structural differences on the observed densities. The PC-SAFT EoS, with pure component parameters from the literature or from a group contribution method, provides improved density predictions relative to those obtained with the PREoS or HTHP VT-PREoS. However, the PC-SAFT EoS, with either set of parameters, also cannot fully account for the effect of the C6 isomer structure on the resultant density.
The Journal of Chemical Thermodynamics, 2014
The Journal of Chemical Thermodynamics, 2013
Experimental high-temperature, high-pressure (HTHP) density data for bis(2-ethylhexyl) phthalate ... more Experimental high-temperature, high-pressure (HTHP) density data for bis(2-ethylhexyl) phthalate (DEHP) are reported in this study. DEHP is a popular choice as a reference fluid for viscosity calibrations in the HTHP region. However, reliable HTHP density values are needed for accurate viscosity calculations for certain viscometers (e.g. rolling ball). HTHP densities are determined at T = (373, 424, 476, 492, and 524) K and P to 270 MPa using a variable-volume, high-pressure view cell. The experimental density data are satisfactorily correlated by the modified Tait equation with a mean absolute percent deviation (d) of 0.15. The experimental data are modeled with the Peng-Robinson (PREoS), volume-translated PREoS (VT-PREoS), and perturbed chain statistical associating fluid theory (PC-SAFT EoS) models. The required parameters for the two PREoS and the PC-SAFT EoS models are determined using group contribution methods. The PC-SAFT EoS performs the best of the three models with a d of 2.12. The PC-SAFT EoS is also fit to the experimental data to obtain a new set of pure component parameters that yield a d of 0.20 for these HTHP conditions.
Macromolecules, 1991
ABSTRACT
Macromolecules, 1996
Experimental cloud-point data to 250°C and 2000 bar are presented to demonstrate the impact of di... more Experimental cloud-point data to 250°C and 2000 bar are presented to demonstrate the impact of dimethyl ether (DME) and ethanol on the phase behavior of poly(ethylene-co-acrylic acid) (3.9 mol % acrylic acid) (EAA3.9)-butane mixtures. The addition of 6.4 wt % DME to the EAA-butane system decreases the cloud-point pressure from 2000 to 650 bar at 165°C due to the cross-association of dimethyl ether and acrylic acid in EAA3.9. At high DME concentrations, its impact is reduced as the amount of DME increases since polar interactions between excess DME increase after the acrylic acid sites are saturated with DME. Ethanol is a better cosolvent than DME at low ethanol concentrations. The addition of 2.2 wt % ethanol decreases the cloud-point pressure from 2000 to 650 bar at 165°C due to the crossassociation of ethanol and acrylic acid in EAA3.9. Ethanol becomes an "antisolvent" at concentrations greater than 16 wt % as excess ethanol self-associates, forming multimers that increase the polarity of the mixture. The cloud-point data are modeled with statistical associating fluid theory (SAFT). The ternary calculations use temperature-independent, binary mixture parameters whose values are obtained by fitting the phase behavior of the three binary pairs that form the ternary system. SAFT correctly predicts the trends observed in the cloud-point curves from zero to 100 wt % DME, although quantitatively it overestimates the effect of DME. SAFT underestimates the effect of ethanol, as the calculated onephase region is smaller than that observed. However, SAFT correctly predicts the decreasing impact of ethanol with increasing ethanol concentration and that ethanol becomes an antisolvent at high ethanol concentrations.
Journal of Polymer Science Part B: Polymer Physics, 1992
SYNOPSIS Cloud-point data to 180°C and 2,800 bar are presented for three poly (ethylene-co-methyl... more SYNOPSIS Cloud-point data to 180°C and 2,800 bar are presented for three poly (ethylene-co-methyl acrylate) copolymers [lo, 31, and 41 mol % methyl acrylate (M A) ] and for polyethylene in ethylene, ethane, propylene, and propane. At low concentrations of MA in the backbone of the copolymer, the saturated hydrocarbons are better solvents for the copolymer than their olefinic analogs because polarizability drives the phase behavior. For the higher MAcontent copolymers, which have more polar repeat units, the unsaturated hydrocarbons are better solvents owing to favorable quadrupolar interactions between the solvent and the polymer segments. The cloud-point curves of the high MA-content copolymers in the unsaturated hydrocarbons are shifted to very high temperatures to overcome strong acrylateacrylate interactions in the polymer. In fact, the 41 mol % MA copolymer cannot be dissolved in propane at temperatures to 180°C and pressures to 2,800 bar even though the copolymer is predominantly ethylene, while the same copolymer dissolves in propylene at 40°C and a t pressures as low as 1,400 bar. Although the Sanchez-Lacombe equation of state is used to model the cloud-point curves, two temperature-dependent mixture parameters are needed for a good fit of the data.
Journal of Chemical & Engineering Data, 2008
High-pressure phase behavior data are reported for statistically random poly(ethylene-co-20.2 mol... more High-pressure phase behavior data are reported for statistically random poly(ethylene-co-20.2 mol %-1butene) (PEB 10) in ethane and deuterated ethane from ambient temperature to 155°C and pressures to 130 MPa. The two cloud-point curves exhibit negative slopes in pressure-temperature (P-t) space with the PEB 10-deuterated ethane curve at higher pressures than the curve in ethane. Data are also reported for statistically random deuterated PEB 10 (d-PEB 10) in n-pentane, isopentane, neopentane, and cyclopentane. Solvent quality orders as cyclopentane > n-pentane g isopentane > neopentane, which is also the same ordering of the solvent critical temperatures. The d-PEB 10-cyclopentane cloud-point curve has a steep positive P-t slope of ≈ 0.28 MPa •°C-1 near 200°C. The d-PEB 10-n-pentane and isopentane curves also have positive P-t slopes of ≈ 0.16 MPa •°C-1 at temperatures between (≈ 100 and 200)°C and pressures to ≈ 15 MPa. The curve for the d-PEB 10-neopentane system is virtually flat at a fixed pressure of ≈ 20 MPa from (200 to ≈ 30)°C, where the curve changes abruptly to a positive slope of ≈ 1.65 MPa •°C-1. The positive-slope portion of this cloud-point curve represents solid + liquid to fluid transitions where the neopentane is the solid phase not the d-PEB 10 , which is amorphous.
Journal of Chemical & Engineering Data, 1989
Preuure-compositlon isotherms for the carbon dietlde-styrene system are obtained at 35, 55, 80, a... more Preuure-compositlon isotherms for the carbon dietlde-styrene system are obtained at 35, 55, 80, and 100 OC. A portlon of the crlticaCmlxture curve Is also obtalned In the vicinity of the crltlcal polnt of pure carbon dloxlde. The resultlng experhnental data are modeled by wing the Peng-Robinson equation of state. Two temperature-lndependent model parameters are used to pbtaln good agreement between calculated and experimental data.
Industrial & Engineering Chemistry Research, 2013
Experimental density data for o-xylene, m-xylene, p-xylene, and 2-methylnaphthalene, are reported... more Experimental density data for o-xylene, m-xylene, p-xylene, and 2-methylnaphthalene, are reported at pressures (P) to 265 MPa and temperatures (T) to 525 K using a variable-volume, high-pressure cell. The reported data agree to within ±0.4% of available literature data. o-Xylene has the largest densities and p-xylene has the smallest densities in the P−T range investigated in this study although the 525 K isotherms for all three aromatics virtually superpose at high pressures. The aromatic densities are modeled using the Peng−Robinson (PR), high-temperature, high-pressure, volume-translated Peng−Robinson (HTHP VT-PR), and perturbed chain statistical associating fluid theory (PC-SAFT) equations of state (EoS). Generally, the PC-SAFT EoS gives the best predictions of the HTHP density data with mean absolute percent deviations (δ) within 1.0%, even though the pure-component parameters are fitted to low-pressure vapor pressure and saturated liquid density data. δ decreases to 0.4% for calculations with a new set of PC-SAFT parameters obtained from a fit of the HTHP experimental density data obtained in this study.
Fuel, 2013
h i g h l i g h t s A technique for solidification determination at high pressures. High-pressure... more h i g h l i g h t s A technique for solidification determination at high pressures. High-pressure solidification data reported for cyclic and aromatic hydrocarbons. Experimental data well represented by quadratic and Simon equations.
Rocket propellants are subjected to extreme thermodynamic conditions in high-performance liquid r... more Rocket propellants are subjected to extreme thermodynamic conditions in high-performance liquid rocket engines, with temperatures in excess of 700 K and pressures nearing 100 MPa. Knowledge of the fuel viscosity is crucial for modeling the performance of liquid rocket engines utilizing rocket grade kerosene rocket propellant 1 (RP-1) or RP-2. The present study reports the viscosity of two RP-2 fuel samples at temperatures from 298 to 573 K and pressures up to 100 MPa. A high-temperature, highpressure (HTHP), variable-volume, close-clearance, windowed, rolling-ball viscometer is used to measure the viscosity based on terminal velocity and RP-2 density. To facilitate the use of the RP-2 viscosity data with computational fluid dynamics (CFD) and other analytical models, these data are modeled with the free volume theory (FVT), with an empirical temperature/pressure-dependent correlation and with a modified form of the Vogel−Fulcher−Tammann (VFT) equation.
Public reporting burden for this collection of information is estimated to average 1 hour per res... more Public reporting burden for this collection of information is estimated to average 1 hour per response, including the time for reviewing instructions, searching existing data sources, gathering and maintaining the data needed, and completing and reviewing this collection of information. Send comments regarding this burden estimate or any other aspect of this collection of information, including suggestions for reducing this burden to Washington Headquarters Services, Directorate for Information Operations and Reports,
International Journal of Pharmaceutics, 2014
This paper describes the synthesis of H 2 O 2-H 2 O filled poly(methyl methacrylate) (PMMA) micro... more This paper describes the synthesis of H 2 O 2-H 2 O filled poly(methyl methacrylate) (PMMA) microcapsules as potential candidates for controlled O 2 delivery. The microcapsules are prepared by a water-in-oil solvent emulsion and evaporation method. The results of this study describe the effect of process parameters on the characteristics of the microcapsules and on their in vitro performance. The size of the microcapsules, as determined from scanning electron microscopy, ranges from ~5 to 30 µm and the size distribution is narrow. The microcapsules exhibit an internal morphology with entrapped H 2 O 2-H 2 O droplets randomly distributed in the PMMA continuous phase. In vitro release studies of 4.5 wt% H 2 O 2 loaded microcapsules show that ~70% of the H 2 O 2 releases in 24 hours. This corresponds to a total O 2 production of ~12 cc per gram of dry microcapsules. Shelf-life studies show that the microcapsules retain ~84 wt% of the initially loaded H 2 O 2 after nine months storage at 2-to-8 °C, which is an attractive feature for clinical applications.
The Journal of Supercritical Fluids, 2013
Chemical Engineering & Technology, 2000
This paper was also published in German in Chem. Ing. Tech. 71 (1999) No. 7, pp. 729±732.
Industrial & Engineering Chemistry Research, 2015
This study reports the high-temperature, high-pressure density data for propane, squalane, and th... more This study reports the high-temperature, high-pressure density data for propane, squalane, and their binary mixtures for five compositions at temperatures to 520 K and pressures to 260 MPa. The density measurements are obtained with a floating-piston, variable-volume, high-pressure view cell. From the density data, the isothermal and isobaric excess molar volumes upon mixing are computed. For the mixture compositions studied here, the excess volume is mostly negative, showing a minimum at 0.6550 mole fraction of propane and becomes less negative as the propane concentration increases. The perturbedchain statistical associating fluid theory (PC-SAFT) equation of state (EoS) provides good representation for the experimental data. A mean absolute percent deviation (δ) of 1.4% is obtained with the PC-SAFT EoS when using propane and squalane pure component parameters fit to density data at high-temperature, high-pressure conditions.
The Journal of Chemical Thermodynamics, 2015
ABSTRACT Binary mixture density data are reported for propane (C3) with n-decane (C10) and with n... more ABSTRACT Binary mixture density data are reported for propane (C3) with n-decane (C10) and with n-eicosane (C20) at T = (320 to 525) K and pressures to 265 MPa. The (C3 + C10) mixture density data are in good agreement with available literature data to 70 MPa, which is the maximum reported literature pressure. There are no available binary mixture density data to compare to the (C3 + C20) mixture density data reported in the present study. The mixture density data are correlated with the Tait equation to facilitate interpolation of the data at different experimental conditions. Equations of state that are suitable for reservoir simulations are used to model the reported data. These models include the Peng–Robinson equation of state (PREoS), a volume-translated PREoS fit to high temperature, high pressure (HTHP) pure component density data, the PC-SAFT EoS, and modifications of the PC-SAFT EoS developed for better representation of HTHP data. The models give superior density predictions for (C3 + C10) mixtures compared to (C3 + C20) mixtures.
ABSTRACT The necessity of exploring ultradeep reservoirs requires the accurate prediction of hydr... more ABSTRACT The necessity of exploring ultradeep reservoirs requires the accurate prediction of hydrocarbon density data at extreme temperatures and pressures. In this study, three equations of state (EoS) models, Peng-Robinson (PR), high-temperature high-pressure volume-translated PR (HTHP VT-PR), and perturbed-chain statistical associating fluid theory (PC-SAFT) EoS are used to predict the density data for hydrocarbons in ultradeep reservoirs at temperatures to 523 K and pressures to 275 MPa. The calculated values are compared with experimental data. The results show that the HTHP VT-PR EoS and PC-SAFT EoS always perform better than the regular PR EoS for all the investigated hydrocarbons.
Fluid Phase Equilibria, 2014
ABSTRACT Experimental phase behavior data are reported for three hyperbranched polyester polymers... more ABSTRACT Experimental phase behavior data are reported for three hyperbranched polyester polymers, Boltorn H20 (B-H20), Boltorn H2004 (B-H2004), and Boltorn U3000 (B-U3000) in supercritical ethane, propane, propylene, CO2, and dimethyl ether (DME) at temperatures to 450 K and pressures to 200 MPa. B-H20 has 100% hydroxyl terminal groups, B-H2004 has 60% saturated C6 and C8 hydrocarbon terminal groups, and B-U3000 has 90% unsaturated C16 and C18 hydrocarbon terminal groups. Cloud point, liquid–vapor, and liquid–liquid–vapor phase transitions are measured with a high-pressure, variable-volume, view cell for each Boltorn polymer at ∼5 wt% in solution. B-H20, with 100% hydroxyl terminal groups, only dissolves in DME, which is expected to hydrogen bond to the polymer hydroxyl groups. At the other extreme, B-U3000, with long chain, nonpolar hydrocarbon terminal groups, is significantly more soluble in nonpolar ethane and propane compared to propylene, CO2, or DME.
The Journal of Physical Chemistry B, 2013
The cis and trans conformation of a branched cyclic hydrocarbon affects the packing and, hence, t... more The cis and trans conformation of a branched cyclic hydrocarbon affects the packing and, hence, the density, exhibited by that compound. Reported here are density data for branched cyclohexane (C6) compounds including methylcyclohexane, ethylcyclohexane (ethylcC6), cis-1,2-dimethylcyclohexane (cis-1,2), cis-1,4-dimethylcyclohexane (cis-1,4), and trans-1,4-dimethylcyclohexane (trans-1,4) determined at temperatures up to 525 K and pressures up to 275 MPa. Of the four branched C6 isomers, cis-1,2 exhibits the largest densities and the smallest densities are exhibited by trans-1,4. The densities are modeled with the Peng-Robinson (PR) equation of state (EoS), the high-temperature, high-pressure, volume-translated (HTHP VT) PREoS, and the perturbed chain, statistical associating fluid theory (PC-SAFT) EoS. Model calculations highlight the capability of these equations to account for the different densities observed for the four isomers investigated in this study. The HTHP VT-PREoS provides modest improvements over the PREoS, but neither cubic EoS is capable of accounting for the effect of isomer structural differences on the observed densities. The PC-SAFT EoS, with pure component parameters from the literature or from a group contribution method, provides improved density predictions relative to those obtained with the PREoS or HTHP VT-PREoS. However, the PC-SAFT EoS, with either set of parameters, also cannot fully account for the effect of the C6 isomer structure on the resultant density.
The Journal of Chemical Thermodynamics, 2014
The Journal of Chemical Thermodynamics, 2013
Experimental high-temperature, high-pressure (HTHP) density data for bis(2-ethylhexyl) phthalate ... more Experimental high-temperature, high-pressure (HTHP) density data for bis(2-ethylhexyl) phthalate (DEHP) are reported in this study. DEHP is a popular choice as a reference fluid for viscosity calibrations in the HTHP region. However, reliable HTHP density values are needed for accurate viscosity calculations for certain viscometers (e.g. rolling ball). HTHP densities are determined at T = (373, 424, 476, 492, and 524) K and P to 270 MPa using a variable-volume, high-pressure view cell. The experimental density data are satisfactorily correlated by the modified Tait equation with a mean absolute percent deviation (d) of 0.15. The experimental data are modeled with the Peng-Robinson (PREoS), volume-translated PREoS (VT-PREoS), and perturbed chain statistical associating fluid theory (PC-SAFT EoS) models. The required parameters for the two PREoS and the PC-SAFT EoS models are determined using group contribution methods. The PC-SAFT EoS performs the best of the three models with a d of 2.12. The PC-SAFT EoS is also fit to the experimental data to obtain a new set of pure component parameters that yield a d of 0.20 for these HTHP conditions.
Macromolecules, 1991
ABSTRACT
Macromolecules, 1996
Experimental cloud-point data to 250°C and 2000 bar are presented to demonstrate the impact of di... more Experimental cloud-point data to 250°C and 2000 bar are presented to demonstrate the impact of dimethyl ether (DME) and ethanol on the phase behavior of poly(ethylene-co-acrylic acid) (3.9 mol % acrylic acid) (EAA3.9)-butane mixtures. The addition of 6.4 wt % DME to the EAA-butane system decreases the cloud-point pressure from 2000 to 650 bar at 165°C due to the cross-association of dimethyl ether and acrylic acid in EAA3.9. At high DME concentrations, its impact is reduced as the amount of DME increases since polar interactions between excess DME increase after the acrylic acid sites are saturated with DME. Ethanol is a better cosolvent than DME at low ethanol concentrations. The addition of 2.2 wt % ethanol decreases the cloud-point pressure from 2000 to 650 bar at 165°C due to the crossassociation of ethanol and acrylic acid in EAA3.9. Ethanol becomes an "antisolvent" at concentrations greater than 16 wt % as excess ethanol self-associates, forming multimers that increase the polarity of the mixture. The cloud-point data are modeled with statistical associating fluid theory (SAFT). The ternary calculations use temperature-independent, binary mixture parameters whose values are obtained by fitting the phase behavior of the three binary pairs that form the ternary system. SAFT correctly predicts the trends observed in the cloud-point curves from zero to 100 wt % DME, although quantitatively it overestimates the effect of DME. SAFT underestimates the effect of ethanol, as the calculated onephase region is smaller than that observed. However, SAFT correctly predicts the decreasing impact of ethanol with increasing ethanol concentration and that ethanol becomes an antisolvent at high ethanol concentrations.
Journal of Polymer Science Part B: Polymer Physics, 1992
SYNOPSIS Cloud-point data to 180°C and 2,800 bar are presented for three poly (ethylene-co-methyl... more SYNOPSIS Cloud-point data to 180°C and 2,800 bar are presented for three poly (ethylene-co-methyl acrylate) copolymers [lo, 31, and 41 mol % methyl acrylate (M A) ] and for polyethylene in ethylene, ethane, propylene, and propane. At low concentrations of MA in the backbone of the copolymer, the saturated hydrocarbons are better solvents for the copolymer than their olefinic analogs because polarizability drives the phase behavior. For the higher MAcontent copolymers, which have more polar repeat units, the unsaturated hydrocarbons are better solvents owing to favorable quadrupolar interactions between the solvent and the polymer segments. The cloud-point curves of the high MA-content copolymers in the unsaturated hydrocarbons are shifted to very high temperatures to overcome strong acrylateacrylate interactions in the polymer. In fact, the 41 mol % MA copolymer cannot be dissolved in propane at temperatures to 180°C and pressures to 2,800 bar even though the copolymer is predominantly ethylene, while the same copolymer dissolves in propylene at 40°C and a t pressures as low as 1,400 bar. Although the Sanchez-Lacombe equation of state is used to model the cloud-point curves, two temperature-dependent mixture parameters are needed for a good fit of the data.
Journal of Chemical & Engineering Data, 2008
High-pressure phase behavior data are reported for statistically random poly(ethylene-co-20.2 mol... more High-pressure phase behavior data are reported for statistically random poly(ethylene-co-20.2 mol %-1butene) (PEB 10) in ethane and deuterated ethane from ambient temperature to 155°C and pressures to 130 MPa. The two cloud-point curves exhibit negative slopes in pressure-temperature (P-t) space with the PEB 10-deuterated ethane curve at higher pressures than the curve in ethane. Data are also reported for statistically random deuterated PEB 10 (d-PEB 10) in n-pentane, isopentane, neopentane, and cyclopentane. Solvent quality orders as cyclopentane > n-pentane g isopentane > neopentane, which is also the same ordering of the solvent critical temperatures. The d-PEB 10-cyclopentane cloud-point curve has a steep positive P-t slope of ≈ 0.28 MPa •°C-1 near 200°C. The d-PEB 10-n-pentane and isopentane curves also have positive P-t slopes of ≈ 0.16 MPa •°C-1 at temperatures between (≈ 100 and 200)°C and pressures to ≈ 15 MPa. The curve for the d-PEB 10-neopentane system is virtually flat at a fixed pressure of ≈ 20 MPa from (200 to ≈ 30)°C, where the curve changes abruptly to a positive slope of ≈ 1.65 MPa •°C-1. The positive-slope portion of this cloud-point curve represents solid + liquid to fluid transitions where the neopentane is the solid phase not the d-PEB 10 , which is amorphous.
Journal of Chemical & Engineering Data, 1989
Preuure-compositlon isotherms for the carbon dietlde-styrene system are obtained at 35, 55, 80, a... more Preuure-compositlon isotherms for the carbon dietlde-styrene system are obtained at 35, 55, 80, and 100 OC. A portlon of the crlticaCmlxture curve Is also obtalned In the vicinity of the crltlcal polnt of pure carbon dloxlde. The resultlng experhnental data are modeled by wing the Peng-Robinson equation of state. Two temperature-lndependent model parameters are used to pbtaln good agreement between calculated and experimental data.
Industrial & Engineering Chemistry Research, 2013
Experimental density data for o-xylene, m-xylene, p-xylene, and 2-methylnaphthalene, are reported... more Experimental density data for o-xylene, m-xylene, p-xylene, and 2-methylnaphthalene, are reported at pressures (P) to 265 MPa and temperatures (T) to 525 K using a variable-volume, high-pressure cell. The reported data agree to within ±0.4% of available literature data. o-Xylene has the largest densities and p-xylene has the smallest densities in the P−T range investigated in this study although the 525 K isotherms for all three aromatics virtually superpose at high pressures. The aromatic densities are modeled using the Peng−Robinson (PR), high-temperature, high-pressure, volume-translated Peng−Robinson (HTHP VT-PR), and perturbed chain statistical associating fluid theory (PC-SAFT) equations of state (EoS). Generally, the PC-SAFT EoS gives the best predictions of the HTHP density data with mean absolute percent deviations (δ) within 1.0%, even though the pure-component parameters are fitted to low-pressure vapor pressure and saturated liquid density data. δ decreases to 0.4% for calculations with a new set of PC-SAFT parameters obtained from a fit of the HTHP experimental density data obtained in this study.
Fuel, 2013
h i g h l i g h t s A technique for solidification determination at high pressures. High-pressure... more h i g h l i g h t s A technique for solidification determination at high pressures. High-pressure solidification data reported for cyclic and aromatic hydrocarbons. Experimental data well represented by quadratic and Simon equations.