Molar Expansibilities Research Articles

Identification of heat transfer intensification mechanism by reversible N2O4 decomposition using direct numerical simulation

Waste heat recovery is an indispensable solution towards high energy efficiency in various industrial processes. While many methods are available to recuperate waste heat of medium-to-high temperature range, limited solutions are applicable at low-temperature (<373 K). The present work presents a potentially reasonable cost while less understood method, namely the reactive heat transfer using reversible exo-/endothermic reactions for harvesting low-grade heat. Invoking high-fidelity direct numerical simulation, the interplay amongst turbulence, heat transfer, and chemical reactions is investigated in a heated channel flow. We consider a temperature difference between hot source and reacting working fluid of 100 K and show a remarkable improvement of heat transfer coefficient by 600% compared to non-reacting working fluid. This is associated with ∽17% higher total energy absorption across the geometry of interest. These improvements are proven to be related to the existence of mild exothermic reactions near the channel core, the molar expansion, and the mild endothermic reaction close to the hot source which contributes to a thin thermal boundary layer, etc.

Computational comparison of the conventional diesel and hydrogen direct-injection compression-ignition combustion engines

Most research and development on hydrogen (H2) internal combustion engines focus on premixed-charge spark ignition (SI) or diesel-hydrogen dual-fuel technologies. Premixed charge limits the engine efficiency, power density, and safety, while diesel injections give rise to CO2 and particulate emissions. This paper demonstrates a non-premixed compression-ignition (CI) neat H2 engine concept that uses H2 pilots for ignition. It compares the CI H2 engine to an equivalent diesel engine to draw fundamental insights about the mixing and combustion processes. The Converge computational fluid dynamics solver is used for all simulations. The results show that the brake thermal efficiency of the CI H2 engine is comparable or higher than diesel, and the molar expansion with H2 injections at TDC constitutes 5–10 % of the total useful work. Fuel-air mixing in the free-jet phase of combustion is substantially higher with H2 due to hydrogen’s gaseous state, low density, high injection velocity, and transient vortices, which contribute to the 3 times higher air entrainment into the quasi-steady-state jet regions. However, the H2 jet momentum is up to 4 times lower than for diesel, which leads to not only ineffective momentum-driven global mixing but also reduced heat transfer losses with H2. The short H2 flame quenching distance may also be inconsequential for heat transfer in CI engines. Finally, this research enables future improvements in CI H2 engine efficiency by hypothesizing a new optimization path, which maximizes the free-jet phase of combustion, hence is totally different from that for conventional diesel engines.

Evaluation of possible interactions for ionic liquids [Emim][HSO4] and [Bmim][BF4] in aqueous sorbitol solutions at T = (293.15–313.15) K by volumetric data

Our systematic volumetric studies on the aqueous solutions containing ionic liquids and carbohydrates is followed in this research by consideration of the ternary (1-butyl-3-methylimidazolium tetrafluoroborate or 1-ethyl-3-methylimidazolium hydrogen sulfate + sorbitol + water) mixtures. For this purpose, via the measured density data, apparent molar volumes, their values at infinite dilution and apparent molar expansibility for these ionic liquids (ILs) in aqueous sorbitol solutions have been calculated. By means of these information, as where as possible, solute =solvent and solute-solute interactions in these systems are discussed. Hydrophilic–hydrophobic hydrophobic–ionic and hydrophobic–hydrophobic interactions are governing in the considered ternary solutions. Both ionic liquids act as structure maker in these solutions.

Densities and apparent molar volumes of diluent solutions of [EmimNTf2], [BmimNTf2], and [BmmimNTf2] in DEGDME and TEGDME

The densities of six diluents with molality of 0.0199to 0.5070 mol·kg−1 were measured at atmospheric pressure from 293.15 to 328.15 K. The studied ionic liquids (ILs) include 1-ethyl-3-methylimidazolium bis[(trifluoromethyl)sulfonyl]imide ([Emim][NTf2]), 1-butyl-3-methylimidazolium bis[(trifluoromethyl)sulfonyl]imide ([Bmim][NTf2]), and 1-butyl-2,3-dimethylimidazolium bis[(trifluoromethyl)sulfonyl]imide ([Bmmim][NTf2]). The solvents include diethylene glycol dimethyl ether (DEGDME) and tetraethylene glycol dimethyl ether (TEGDME). The measured densities were applied for calculation of VÐΦ/m3·mol-1 (apparent molar volume) from 293.15 K to 328.15 K. The influence of the introduction of methylene (–CH2-), methyl (–CH3) groups, and the structure of solvents on the density, apparent molar volume were discussed in depth. Redlich-Rosenfeld-Meyer (RRM) equation was used to fit VÐΦ/m3·mol-1 dependence on the molality of the six studied diluent solutions. Two parameter of VÐΦo/m3·mol-1 (infinite dilution apparent molar volume) and EÐΦ0/m3·mol-1·K-1 (limiting apparent molar expansibility) were also been fitted and discussed based on the RRM equation and polynomial equation, respectively. Besides, the interactions of ion-ion and ion–solvent were discussed according to the fitted parameters. The structure making or breaking were also discussed for IL in solvent.

Studies on synthesis, volume and conductivity behaviors of three novel pharmaceutical salts [CnPy][AceSA] (n = 8, 10, 12)

In the present work, three new pharmaceutical salts based on N-alkyl-pyridinium ([CnPy]+, n = 8, 10, 12) as the cations and acetyl-sulfacetamide ([AceSA]-) as an anion were synthesized. The thermal stability was measured by synchronous thermal analyzer. The solvation and micellization behaviors in aqueous solution were investigated by experimental density and conductivity data at different temperatures. These data were used to calculate the apparent molar volume at infinite dilution, V2,φ0, the apparent molar expansibility at infinite dilution, Eφ0, limiting molar conductivity, Ʌ0, critical micelle concentration, cmc, and the relative thermodynamic functions for the micellization of [CnPy][AceSA] in aqueous solution. The effect of the aliphatic chain length of N-alkyl-pyridinium cation and temperature on the estimated properties was examined. The obtained results confirmed that [CnPy]+(n = 8, 10, 12) cations with longer alkyl chain exhibit higher decomposition temperature, large V2,φ0, low cmc and Ʌ0 values. The results were discussed in terms of solute–solvent interactions and structural changes of [CnPy][AceSA] in water.

Using Volumetric Method the Study of Molecular Interactions of NSAID (DP) in Water and Water + 1M Urea at Different Temperatures

Understanding possible interactions of drugs and the factors that command such interactions could be helpful to control their disadvantageous effects upon human health. In this study, volumetric properties for the solution of diclofenac potassium (DP), a non-steroidal anti-inflammatory drug (NSAID), were investigated for the first time to look into its molecular interactions at four different temperatures varying from 298.15 K to 313.15 K at 5 K intervals in water as well as aqueous hydrotropic agent urea (1M) solutions. Experimental density data obtained using a pycnometer have been taken to estimate apparent molar properties, i.e., limiting apparent molar volume (〖V_ɸ〗^0), apparent molar volume (V_ɸ), limiting apparent molar expansibility (〖E_ɸ〗^0) and apparent molar expansibility (E_ɸ). The results obtained were discussed in terms of solute-solvent and solute-solute interactions in the studied systems. The obtained results from volumetric data were explored in terms of the existence of solute-solvent interactions in aqueous systems of drug solutions.

Effect of ethylene glycol/diethylene glycol/triethylene glycol on the thermodynamics of the aqueous biotin solutions at various temperatures

Acoustic and volumetric parameters for the liquid mixture (water + Biotin + ethylene glycol/diethylene glycol/triethylene glycol) are evaluated at different temperatures (288.15 K, 298.15 K, 308.15 K, and 318.15 K) and constant pressure of 0.1 MPa over the range of biotin concentrations (0.0000, 0.0015, 0.0025, and 0.0035) mol·Kg-1. The experimental work was carried out by Anton Paar DSA 5000 M, where the density (ρ) and the speed of sound (c) are measured, which are later used to determine the various derived thermodynamic properties, such as, apparent molar properties (apparent molar volume, Vϕ; apparent molar isentropic compression,Kϕ,S), the partial molar properties (partial molar volume, Vϕ0; partial molar isentropic compression, Kϕ,S0), the partial molar transfer properties (partial molar volume of transfer, ΔVϕ0; partial molar isentropic compression of transfer, ΔKϕ,S0) and the partial molar expansibility (Eϕ0) along with its first derivative ∂Eϕ0/∂TP. The obtained results are explained in terms of the kind of intermolecular interactions developed in the mixture using the co-sphere overlap model. Further, with the partial molar properties, the pair and triplet interaction coefficients (VAB,KAB; VABB, KABB) are calculated.

Studies on volumetric and acoustic behfavior of L-alanine and L-leucine in aqueous 1-dodecyl-3-methylimidazolium bromide ionic liquid solutions at different temperatures

In this work density (ρ) and speed of sound (c) of a ternary system containing {1-dodecyl-3-methylimidazolium bromide + water + L-alanine or L-leucine} have been determined at five working temperatures, T= (288.15, 293.15, 298.15, 303.15 and 308.15) K. From density data, thermodynamic parameters like the apparent molar volumes (Vϕ), the apparent molar volumes at infinite dilution (Vϕ0) and partial molar volume of transfer ΔVϕ0has been determined. Speed of sound data has been used to determine parameters like partial molar isentropic compression (Kϕ,s), partial molar isentropic compression at infinite dilution (Kϕ,s0) and partial molar isentropic compression of the transfer ΔKϕ,S0. The limiting apparent molar expansibilities at infinite dilution ϕE0= (∂Vϕ0/∂T)p deliver valuable information about the (solute–solvent) interactions present in the system. These parameters provide information about the molecular interactions prevailing between amino acids and ionic liquid.

Effect of some choline based deep eutectic solvents on volumetric and ultrasonic properties of gabapentin drug in water at T = (288.15 to 318.15) K

A key part of the drug preparation process is the optimization of molecular interactions between drugs and solvents. Thermodynamic properties provides complete information on interactions and the selection of suitable solvents for various pharmaceutical processes. Especially, the investigation of antiepileptic drugs in aqueous solutions has been a subject of interest because they employ their effect by interaction with biological membranes. In this study, the density and speed of sound for the gabapentin (GBP) in aqueous deep eutectic solvents (DESs), (choline chloride/ethylene glycol (ChCl/EG), choline chloride/glycerol (ChCl/Gly), and choline chloride/urea (ChCl/U)) as novel category of green solvents were measured at temperature range 288.15 K to 318.15 K. The apparent molar volumes Vφ, apparent molar isobaric expansion Eφ0, Hepler’s constant and apparent molar isentropic compressibility κφ were calculated from the density and speed of sound data. Findings show that Vφ values are higher for binary systems compared to ternary systems. The order of Vφ values for aqueous DESs solutions are as follows: ChCl/EG > ChCl/U > ChCl/Gly. The standard partial molar volume Vφ0 and partial molar isentropic compressibility κφ0 were obtained by using the Redlich-Meyer equation. The obtained results for the Vφ0 quantity indicate a strong interaction between the GBP drug and the ChCl/Gly. Finally, using the results of Eφ0, it is understood that GBP has acted as a structure maker in the presence of all DESs.

Studies of intrinsic volumes of ethylene glycol and polyethylene glycol–300 molecules in aqueous solutions at 298.15 K: Application of Tammann–Tait–Gibson (TTG) equation of state

Systemic density (ρ) measurements have been carried–out for aqueous solutions of polyethylene glycols (PEG's) with the molar mass 200, 300, 400 and 600 D at (288.15, 293.15, 298.15, 303.15 and 308.15) K and at ambient pressure of 0.1 MPa in dilute solute concentration region (0.0119–0.4941 mol⋅kg−1). The ρ data are used to obtain the apparent molar volume (Vϕ) and partial molar volume (V¯2) of studied PEG's in aqueous solutions at finite concentration as well as at infinitely dilute solutions (Vϕ0) at studied temperatures. The coefficient of thermal expansion (α) for solutions, apparent molar expansivity (Eϕ) and limiting apparent molar expansivity (Eϕ0) for solutes are calculated at 293.15, 298.15 and 303.15 K. The densities of studied PEG's in carbon tetrachloride (CCl4) medium are also measured at 298.15 K. The transfer volume (ΔtrVϕ0) for PEG from pure liquid state to CCl4 and to water as solvent are estimated. The literature data of sound velocity (u), coefficient of thermal expansion (α) and specific heat capacity (CP) for solutions have been utilized to obtain thermodynamic properties like adiabatic compressibility (βad) and isothermal compressibility (βT) in case of aqueous solutions of ethylene glycol (EG) and PEG–300 at 298.15 K. The data are further utilized to obtain apparent molar adiabatic compressibility (KϕS) and apparent molar isothermal compressibility (KϕT) for EG and PEG–300 solute molecules at finite and at infinitely dilute solute concentration (KϕS0 and KϕT0, respectively). Further, the data of KϕT, α and CP data have been utilized to estimate internal pressure Pi (=∂U∂VT) of solutions containing EG and PEG–300 molecules as a function of concentration. The intrinsic volumes (Vint.) of these molecules have been calculated by applying Tammann–Tait–Gibson (TTG) equation of state. It is being observed that intrinsic volume differs appreciably from the value based upon EG and PEG–300 in a liquid state as a standard state. The excess volume change (V¯20E=V¯20-V¯int.0) values are found to be −16.1 and −63.8⋅10–6 m3⋅mol−1 for EG and PEG–300, respectively. Similar calculations made for PEG–300 in CCl4 medium also yield excess volume change of −60⋅10–6 m3⋅mol−1 magnitude. These results are explained on the basis of three dimensional hydrogen bonded structure of EG and the linkage ▪ interaction with solvent water having a presence of helical segments. The inferences drawn will be of help to understand the weak denaturing interactions of glycols in protein denaturation studies.

Physicochemical study on molecular interactions of the active pharmaceutical ingredient ionic liquid domiphen salicylate with amino acids at different temperatures

The molecular interactions between the active pharmaceutical ingredient ionic liquid domiphen salicylate ([Dom][Sal]) and some amino acids (glycine, L-alanine, L-valine, L-leucine) in aqueous solution were studied. In order to accomplish this objective, the volume, conductivity and UV–vis spectroscopy of ternary systems were measured at different temperatures. The infinite dilution apparent molar volume, V2,φ0, transfer volume, ΔtV0, hydration number, nH and infinite dilution apparent molar expansibility, Eφ0 of amino acids in aqueous [Dom][Sal] solution were derived from the measured density data. Side chain contributions to V2,φ0 have been estimated. Critical micelle concentration, cmc, and thermodynamic properties of micellization (ΔGm0, ΔHm0,ΔSm0) for [Dom][Sal] in aqueous amino acids solutions were calculated using electrical conductivity data. The binding constant Kb of the amino acid with [Dom][Sal] was estimated based on the maximum absorbance data of the UV–vis spectroscopy. The impacts of temperature, concentration and the length of aliphatic chain of amino acids on these parameters were discussed. The mentioned parameters was employed to unveil the solute–solvent interactions in ternary systems.

Solvodynamic study on Solubility Enhanced Lovastatin in presence of Arginine as Cosolute

In this study, the solute-cosolute interaction, solute-solvent interaction involved in the solubilisation process of ARG solutions and LVS-ARG solution systems are illustrated. The sound velocity values of both solution systems were determined at varying concentrations of ARG (0.01-0.8 mol.dm-3) at 298.15 K. Next, the refractive index and the density of the solution systems was measured at temperature range from 298.15 to 313.15K. Acoustic and volumetric parameters such as isentropic compressibility (KS), apparent isentropic molar compressibility (KSΦ), relative association (RA), acoustic impedance (Z), internal pressure (πi), free volume (Vf), molar volume (Φv0), molar expansibility (ΦE0) were calculated from sound velocity and density data. From the study, an increasing trend in sound velocity was observed with the increase in ARG concentration while compressibility values showed opposite trend. Additionally, solute-solvent interaction and structural effects of water for ARG and LVS-ARG systems are discussed regarding the changes in acoustic parameters.

Molecular interactions of two biologically active molecules (L–serine and L-valine) in aqueous [Hmim]Cl solutions: Volumetric and viscometric approach

Mixtures of amino acids L–serine and L–valine + (0.05, 0.1, 0.2 and 0.3 mol·kg−1) aqueous solutions of ionic liquid 1-n-hexyl-3-methylimidazolium chloride, [Hmim]Cl, at temperatures T = (293.15, 298.15, 303.15, 308.15 and 313.15 and 318.15 K) have been studied using density and viscosity measurements. From density, the volumetric properties: the apparent molar volume, Vϕ, limiting partial molar volume, Vϕ0, and expansibility, Eϕ0, standard molar volume of transfer, ΔVϕ0, and hydration number, nH, were calculated. Similarly, from viscosity measurements and using the Jones–Dole equation and transition state treatment, the viscosity B coefficient and some activation parameters of viscous flow were calculated. These parameters, their variation with temperature and concentration, were discussed in terms of transition state theory. Based on the co-sphere overlap model, the solute–solute and solute–solvent interactions were discussed, including amino acids hydration, and structural effects. The structure making/breaking ability of the amino acids in solutions was also discussed using Hepler's constant and (dB/dT) variation.

Investigations on volumetric, compressibility and viscometric properties of L-ascorbic acid and thiamine hydrochloride in aqueous 1-ethyl-3-methylimidazolium hydrogen sulfate solutions at different temperatures

A comprehensive study on volumetric, compressibility, and viscometric properties of two vitamins namely L-ascorbic acid and thiamine hydrochloride in aqueous and (0.05, 0.10, and 0.15 mol kg−1) binary aqueous 1-ethyl-3-methylimidazolium hydrogen sulfate media has been done. The physical properties like density, speed of sound, and viscosity have been estimated at six discrete temperatures (293.15–318.15) K and ambient pressure (0.1 MPa). The thermophysical parameters like apparent molar volume (Vϕ), partial molar volume (Voϕ), partial molar expansivity (Eϕo), Hepler’s constant ∂Eϕo∂TP, apparent molar isentropic compressibility (Kϕ,s), partial molar isentropic compressibility (Kϕ,so), acoustic and volumetric interaction coefficients (KAB, KABB, VAB, VABB), Jones-dole coefficients (A and B) etc are deliberated. Cosphere overlap model was employed for the understanding of various types of molecular interactions that are established in the studied systems. Also, the structure breaking ability of both vitamins have been examined through the positive sign of dBdT values and negative sign of ∂Eϕo∂TP values. Moreover, this study provides the crucial data imperative for the designing of several industrial processes.

Studies of solute–solvent interactions of imidazolium-based ionic liquid in water and aqueous l-alanine solution via volumetric and compressibility properties at T = (293.15–313.15) K

The assessment of stability and behavior of ionic liquid is possible through the study of molecular interactions of the ionic liquid in water and mixed aqueous l-alanine solutions. We have studied density (ρ) and speed of sound (u) parameters at various temperatures. Derived parameters like apparent molar volume (Vϕ) and apparent molar isentropic compressibility (KS,ϕ) of solutes are calculated in the temperature range of 293.15 K–313.15 K. For aqueous binary and ternary solutions having ionic liquid [EMIm][MeSO4] and l-alanine as solute components. For ternary aqueous solutions concentration of l-alanine was kept constant (0.05 mol.kg−1). The limiting apparent molar volume (Vϕ0) and compressibility (KS,ϕ0) values for IL are estimated by using smooth extrapolation of Vϕ and KS,ϕ data. In both binary and ternary systems, the limiting apparent molar expansivity (Eϕ0) of solute and coefficient of thermal expansion (α*) and hydration number (nh) parameters have been calculated. The estimation of transfer parameters i.e., transfer volume and transfer compressibility results for transfer of IL from aqueous to aqueous l-alanine solutions are explained in terms of ion–solvent and hydrophobic interaction effects.

Temperature dependent physicochemical studies propylene and hexylene glycols in methanol solutions of chlorhexidine

The experimentally obtained density (ρ) and sound velocity (c) values of chlorhexidine (methanol solution) at a concentration of (0.0015, 0.0035 and 0.0055) mol∙kg-1 with propylene and hexylene glycols at the temperature of 288.15, 298.15, 308.15 and 318 K have been used to calculate the various physico-chemical properties. Apparent molar volume (Vϕ) and apparent molar isentropic compression (Kϕ,s) have been computed by using density and sound velocity data respectively. Partial molar volume (Vϕ0) and partial molar isentropic compression (Kϕ,s0) have been determined by using apparent molar properties. Empirical parameters and limiting apparent molar expansibilities have also been calculated. These parameters give information in the form of strong solute–solvent interactions which increases from propylene to hexylene glycols.

Liquid phase PVTx properties of {water (1) + 1,3-dimethylurea (2)} mixtures at temperatures from 278.15 to 323.15 K and pressures to 100 MPa

In this study, the compression coefficients k=ΔV/Vo of the binary mixture {water (1) + 1,3-dimethylurea (2)} were measured within the temperature range from 278.15 K to 323.15 K (278.15, 288.15, 288.15, 308.15, 323.15), the pressure range from 10 to 100 MPa (10, 25, 50, 75 and 100) and the composition range up to x2 = 0.19364 (1,3-dimethylurea mole fraction). The molar isothermal compression, KT,m, molar isobaric thermal expansion, EP,m, isochoric coefficient of thermal pressure, βV, and the internal pressure of the mixture, Pint, were calculated. It was demonstrated that the concentration dependences (on the mole fraction of 1,3-dimethylurea (1,3-DMU)) of the molar isothermal compressions of the mixture at low pressures and low temperatures are characterized by a minimum at x2≈0.06 ÷ 0.07, which levels out both with increase in pressure and with increase in temperature. The molar isobaric thermal expansion of the mixture increases with an increase in the 1,3-DMU concentration for all state parameters. At low temperatures, the concentration dependences of the molar expansion are characterized by the presence of a pressure inversion zone. The concentration dependences of the isochoric coefficient of thermal pressure of the mixture indicate the hydrophobic properties of the 1,3-DMU molecule become stronger at high pressures. The obtained results are discussed in terms of solute–solvent and solute–solute interactions.

Temperature-dependent thermodynamic and physicochemical studies of glycols in aqueous biotin solutions

The current study deals with the analysis of the molecular interactions among the glycols (propylene glycol, PG and hexylene glycol, HG) molecules in (0.000, 0.001, 0.002 and 0.003) mol·Kg-1 aqueous solutions of biotin at constant experimental pressure 0.1 MPa and temperature range (288.15 K, 298.15 K, 308.15 K and 318.15 K). The speed of sound and the density for the liquid mixtures is measured with Anton Paar DSA 5000 M. Numerous thermodynamic and acoustic parameters are determined using these experimental data. The apparent molar volume (Vϕ), partial molar volume (Vϕ0), partial molar volume of transfer (ΔVϕ0), apparent molar isentropic compression (Kϕ,S), partial molar isentropic compression (Kϕ,S0), partial molar isentropic compression of transfer (ΔKϕ,S0) were estimated using the experimentally obtained density and speed of sound respectively along with the partial molar expansibility(Eϕ0), its first-order derivative ∂Eϕ0/∂TP and pair-triplet interaction coefficients (VAB,KAB,VABB; KABB). The apparent molar properties recommend the existence of strong (solute and solvent) interactions in the ternary mixture which is also justified by the positive partial molar expansibility values, while the partial molar properties suggest the formation of the hydrogen bond in the mixture. With Passynski's equation the hydration number (nh) for PG/HG in aqueous solutions of biotin is calculated utilizing the compressibility data and the obtained results are explained in terms of combined hydration effects and hydrophobic effect.

Effect of position of OH group in isomeric butanediols on intermolecular interaction with Choline Acetate: A thermodynamic study at different temperatures

The prominent effect of the position of hydroxyl groups in isomeric butanediols i.e.1,3-butanediol (1,3-BTD), 1,2-butanediol (1,2-BTD) and 2,3-butanediol (2,3-BTD) on intermolecular interactions with Choline Acetate has been investigated using various thermophysical parameters such as density ρ, speed of sound u, refractive index nD and specific conductivity κ over different concentration range and at temperatures varying from 293.15 to 323.15 K at atmospheric pressure. To gain further insight the derived parameters such as apparent molar volumes Vϕ, apparent molar isentropic compressibilities Ksϕ, and their infinite parameters mainly limiting apparent molar volumes at infinite dilution Vϕo, limiting apparent molar expansibilities Eϕo, limiting isentropic compression Kϕo, molar refraction Rm and infinite molar conductance ̂mo values have been calculated. The least values obtained for apparent molar volumes and compressibilities in case of 1,3-BTD mixtures are attributed to its highest ability to form intramolecular hydrogen bonding among isomeric butanediols and thus lesser availability to interact with Choline Acetate molecules. However for 2,3-BTD and 1,2-BTD binary mixtures the results have been explained on the basis of hydrophobic or iceberg effect where alkyl groups are present either on one end (1,2-BTD) or at both ends (2,3-BTD) while OH groups are located at vicinal carbon atoms.

The density, viscosity, speed of sound, excess properties of binary mixtures of linear polydimethylsiloxane and various alkanes at temperatures in the range (288.15–328.15) K

This article describes the binary system composed of linear polydimethylsiloxane (PDMS) and diesel fuel main components n-decane, n-dodecane, n-tridecane and n-tetradecane at atmospheric pressure, and the density, viscosity and speed of sound were measured at 288.15 K, 298.15 K, 308.15 K, 318.15 K and 328.15 K, respectively. Their excess molar volume (VmE), excess viscosity (ηE), excess molar Gibbs free energy (ΔGEm), molar isobaric thermal expansion (EP,m) and excess molar isentropic compressibility (κEs,m) were calculated. The influence of the intermolecular force, steric hindrance, molecular stacking and other factors on the excessive properties of the binary system solution was discussed. The results indicate that with an increase in carbon chain length, the excess molar volume, excess viscosity, molar isobaric thermal expansion and excess molar isentropic compressibility increased and excess molar Gibbs free energy decreased, which probably ascribe to the increase in steric effect and the stronger interactions between homo-molecular than those of hetero-molecular interactions between PDMS and long-chain alkane molecules.