Binary Mixtures of Aromatic Compounds (n-Propylbenzene, 1,3,5-Trimethylbenzene, and 1,2,4-Trimethylbenzene) with 2,2,4,6,6-Pentamethylheptane: Densities, Viscosities, Speeds of Sound, Bulk Moduli, Surface Tensions, and Flash Points at 0.1 MPa

Abstract

This study presents measured densities, viscosities, speeds of sound, surface tensions, and flash points and calculated bulk moduli of mixtures of 2,2,4,6,6-pentamethylheptane with C9H12 isomers (1,3,5-trimethylbenzene, 1,2,4-trimethylbenzene, and n-propylbenzene). The densities, speeds of sound, bulk moduli, and surface tensions increase and viscosities decrease as the mole fraction of the C9H12 isomer increases. Flash points decreased, remained the same, and increased as the amounts of n-propylbenzene, 1,3,5-trimethylbenzene, and 1,2,4-trimethylbenzene increased, respectively. Ideal behavior was found for viscosity, in which the excess molar Gibbs energies of activation for viscous flow did not differ statistically from zero. Nonideal behavior was found for excess molar volumes, V m E, and excess speeds of sound, c E, which were positive for all mixtures. Molecular dynamics (MD) simulations were used to predict the densities, bulk moduli, surface tensions, and viscosities of these binary mixtures. Although the densities, bulk moduli, and surface tensions were correctly reproduced, the simulations predicted nearly constant viscosities as a function of composition. The MD simulations showed that the molecular-level fluid structure of n-propylbenzene differed from that of 1,3,5-trimethylbenzene and 1,2,4-trimethylbenzene and that the preferential orientation of the aromatic rings of all three molecules was disrupted upon mixing with 2,2,4,6,6-pentamethylheptane. Finally, the mixtures showed an enrichment of 2,2,4,6,6-pentamethylheptane near the liquid–vapor interface. This interfacial enrichment depended on the mixture composition, with high C9H12 mole fractions leading to a larger degree of 2,2,4,6,6-pentamethylheptane enrichment at the interface.

Volumetric and Viscometric Properties of Maltitol in Glycylglycine Aqueous Solutions at T = 293.15–333.15 K

“…Before measuring the viscosities of solutions, the Ubbelohde viscometer was calibrated using ultrapure water and a standard viscosity liquid (S3­(L), Anton Paar, Austria) at different temperatures. The viscosity η of solutions can be calculated by the following formula according to Poiseuille’s law where ρ is the density of solution, c and b are the viscosity constants of the Ubbelohde viscometer, and t is the flow time.…”

Properties of Binary Mixtures of 2,2,4,6,6-Pentamethylheptane (iso-Dodecane) with iso-Butylbenzene, sec-Butylbenzene, tert-Butylbenzene, or 1,3-Diethylbenzene: Densities, Viscosities, Speeds of Sound, and Isentropic Bulk Moduli in the Temperature Range of 288.15–333.15 K, Surface Tensions at 295 K, and Flash Points at 0.1 MPa

“…26,31,47,48 Simulations of n-propylbenzene, 1,2,4-trimethylbenzene, and 1,3,5-trimethylbenzene showed that the pure aromatic compounds were oriented with their benzene rings in both parallel (angles near 0°) and perpendicular arrangements, with the long-chain propyl compound having a larger probability of the in-parallel configuration than the others. 26 In mixtures with iso-dodecane, the probability of finding these molecules with their aromatic rings in parallel arrangements increased in comparison to that in the pure aromatic liquids. 26 This alteration in the orientation of the alkylbenzene molecules in the presence of iso-dodecane was likely to contribute to the positive excess molar volumes determined experimentally for these binary mixtures.…”

“…26 In mixtures with iso-dodecane, the probability of finding these molecules with their aromatic rings in parallel arrangements increased in comparison to that in the pure aromatic liquids. 26 This alteration in the orientation of the alkylbenzene molecules in the presence of iso-dodecane was likely to contribute to the positive excess molar volumes determined experimentally for these binary mixtures. For mixtures of n-alkylbenzenes with nhexadecane, Morrow et al reported changes in molecular orientation of the aromatic ring in the benzene and toluene in the presence of n-hexadecane, but for ethyl-, n-propyl-and nbutylbenzene, this change in the aromatic ring orientation was small.…”

“…25,27−29 Excess speeds of sound of propylbenzene, 1,3,5-trimethylbenzene, and 1,2,4trimethylbenzene with iso-dodecane were positive. 26 No study, however, has investigated the properties of isododecane mixtures with iso-butylbenzene, sec-butylbenzene, tert-butylbenzene, or 1,3-diethylbenzene. This study reports on the measured density, viscosity, speed of sound, surface tension, and flash point of two-component mixtures of these aromatic compounds in iso-dodecane and compares trends with binary mixtures of these aromatics in n-dodecane.…”

Probing the high-pressure viscosity of hydrocarbon mixtures using molecular dynamics simulations

“…A common theme in the successful entries was the use of an allatom force field, which has been shown previously to be important for accurate viscosity predictions of long-chain hydrocarbons. 28 Several other studies have used MD simulations to investigate the viscosity of hydrocarbon mixtures; [37][38][39][40][41][42][43][44][45][46] however, only a few of these have calculated viscosities at elevated pressure. In a recent study, Verma et al 42 studied the viscosity of n-octane + n-dodecane and n-hexadecane + ndecylbenzene binary mixtures up to 200 MPa using the Green-Kubo method.…”