Thermodynamics, Dynamics, and Rheology of Fuel Surrogates: Application of the Time–Temperature Superposition Principle in Molecular Dynamics Simulations

Perego, Alessandro; Khabaz, Fardin

doi:10.1021/acs.energyfuels.0c01183

Cited by 11 publications

(7 citation statements)

References 71 publications

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“…The viscosity values are plotted versus the Weissenberg number Wi = γ̇τ R , where γ̇ is the shear rate and τ R is the Rouse relaxation time of the hexadecane molecules, as seen in Figures a–d. Note that the Rouse relaxation time was obtained from τ R = ⟨ R 2 ⟩/ D , where ⟨ R 2 ⟩ and D are the square of the end-to-end distance and the diffusion coefficient of hexadecane at given temperatures for all systems, respectively …”

Section: Resultsmentioning

confidence: 99%

“…The ILs (1-( n -alkyl)-3-methylimidazolium bistriflimide, [C n C 1 Im ] + [NTf 2 ] − ) and (1-(isoalkyl)-3-methylimidazolium bistriflimide, [( n – 2) m C n –1C 1 Im ] + [NTf 2 ] − ) were dispersed in hexadecane as the base oil (see Table for the chemical structures of the cations and anions). Hexadecane is a conventional oil that is often used as a reference for fuel mixtures. , The number of hexadecane molecules in the mixture was kept at 1024, while ion pairs were added to obtain IL mole fractions of 0.02, 0.05, 0.1, and 0.2 accordingly, as provided in Table . These IL contents were selected to study the thermo-rheological properties of the mixture at low and high contents when ILs can be considered as “additives” in the base oil.…”

Section: Simulation Details and Methodologymentioning

confidence: 99%

“…On the other hand, the AM1-bcc method , was used to assign charges for carbon and hydrogen atoms of hexadecane that have previously shown consistent results for the dynamics and rheology of this model oil with experiments . To calculate van der Waals and electronic interactions, a potential energy cutoff distance of 12 Å was used.…”

Section: Simulation Details and Methodologymentioning

confidence: 99%

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Thermodynamics and Rheology of Imidazolium-Based Ionic Liquid–Oil Mixtures: A Molecular Simulation Study

Lazarenko

Khabaz

2021

J. Phys. Chem. B

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Conventional lubricants decrease the wear and friction between rolling and sliding surfaces while raising environmental concerns. The thermodynamics and flow behavior of lubricants that contain environmentally friendly additives such as ionic liquids (ILs) are of interest to industries that require lubricants with superior tribological properties. Noncorrosive ILs are promising additives for conventional oil that not only further decrease friction but also create a less hazardous alternative to existing lubricants. In this study, thermodynamics, dynamics, and rheology of IL−oil mixtures are studied by using atomistically detailed molecular dynamics (MD) simulations. A combination of different imidazolium-based cations with linear) and bis[(trifluoroethane)sulfonyl]imide ([NTf 2 ] − ) anion are selected as the model IL which is suspended in bulk hexadecane. The effects of IL content, architecture, size of cation, and temperature are examined on the thermorheological and dynamics of the IL−hexadecane mixture. At equilibrium, ILs self-assemble and create clusters with different shapes and sizes and affect the dynamics and rheology of the mixtures. Mixtures show a significant deviation from ideal solutions behavior. Shear and extensional rheology simulations show that mixtures mostly show Newtonian behaviors at low and moderate rates which is followed by a weak thinning behavior at high rates. It is shown that a small addition of ILs (x=2% mole fraction) to oil significantly increases both the shear and extensional viscosity of the mixture by a factor of 3.

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Section: Resultsmentioning

confidence: 99%

Section: Simulation Details and Methodologymentioning

confidence: 99%

Section: Simulation Details and Methodologymentioning

confidence: 99%

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Thermodynamics and Rheology of Imidazolium-Based Ionic Liquid–Oil Mixtures: A Molecular Simulation Study

Lazarenko

Khabaz

2021

J. Phys. Chem. B

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“…where d = 3 is the space dimension of the considered system. Besides, in the case of MD simulations with periodic boundary conditions, it was found that the final value of diffusion coefficient, D, needs to be corrected by following term [61] which takes into account the size of the box and the shear viscosity. It reads:…”

Section: Mass Diffusivitymentioning

confidence: 99%

Thermophysical properties of $n$-hexadecane: Combined Molecular Dynamics and experimental investigations

Klochko,

Noel,

Sgreva

et al. 2022

Preprint

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Investigating properties of phase change materials (PCMs) is an important issue due to their extensive use in heat storage systems and thermal regulation devices. Improvement of the efficiency of such systems should be based on a better knowledge of the microscopic mechanisms governing the thermal and rheological characteristics of PCMs. This may be accomplished by the use of molecular simulations of the aforementioned quantities and their linkage with macroscale investigations. In this work, we studied thermophysical properties of n-hexadecane for different temperatures regimes using molecular dynamics (MD) and carry out several experimental measurements. Particularly, we focused on the evaluation of various rheological and thermal properties such as thermal conductivity, κ, viscosity, η, diffusion coefficient, D, and heat capacities Cp and Cv. Special attention was paid to the comparison of the results of simulations with experimental ones.

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“…TTS can also be used in simulations to address the challenge. Prior works have shown the applicability of TTS in MD studies (both atomistic and coarse-grained) of alkanes, cross-linked epoxy networks, , dynamic covalent networks such as vitrimers, functionalized polyethylenes, asphalt, fuel surrogates, and ionic liquids (IL) . In particular, Balogun et al studied the volumetric, dynamic, and rheological properties of ILs, and using the TTS principle, they accessed the full spectrum of the rheological behavior of the IL system.…”

Section: Introductionmentioning

confidence: 99%

Rheology of Styrene–Butadiene Rubber: Bridging the Gap between Timescales of Atomistically-Detailed Molecular Simulations and Experiments

Perego

Mani

Khabaz

2022

ACS Appl. Polym. Mater.

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We present an atomistically-detailed molecular dynamics (MD) simulation study of the rheology and dynamics of a single styrene−butadiene rubber (SBR) chain. The density and coefficient of thermal expansion of the simulated system are consistent with the experimental observations. Nonequilibrium molecular dynamics (NEMD) is used to characterize the storage and loss moduli of SBR. Both rheological and dynamic (mean squared displacement) properties of SBR successfully collapse onto universal curves using a set of shift factors with the help of the time−temperature superposition (TTS) principle. The mismatch in the timescale of MD simulations and experiments is resolved by rescaling the shift factors to accommodate the influence of the fast cooling rate present in MD simulations. Both storage and loss moduli show an excellent agreement between simulations and experimental results. As rheology simulations are performed under nonequilibrium conditions, they are often computationally expensive; thus being able to determine the shift factors from simulations under equilibrium conditions has the potential to significantly reduce the computational cost of these simulations. Furthermore, the ability to bridge the timescale difference between experiments and simulations allows MD simulations to predict the rheology of polymers such as SBR at a wide range of frequencies.

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Thermodynamics, Dynamics, and Rheology of Fuel Surrogates: Application of the Time–Temperature Superposition Principle in Molecular Dynamics Simulations

Cited by 11 publications

References 71 publications

Thermodynamics and Rheology of Imidazolium-Based Ionic Liquid–Oil Mixtures: A Molecular Simulation Study

Thermodynamics and Rheology of Imidazolium-Based Ionic Liquid–Oil Mixtures: A Molecular Simulation Study

Thermophysical properties of $n$-hexadecane: Combined Molecular Dynamics and experimental investigations

Rheology of Styrene–Butadiene Rubber: Bridging the Gap between Timescales of Atomistically-Detailed Molecular Simulations and Experiments

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