Volumes of mixing and theP * effect: Part I. Hexane isomers with normal and branched hexadecane

The Prigogine-Flory theory of solution thermodynamics has been used to interpret molar excess volume data, V ^E , for two series of alkane mixtures: the five isomers of hexane mixed with normal hexadecane (Data from Reeder, et al.) and the five hexane isomers mixed with a highly branched hexadecane isomer, 2,2,4,4,6,8,8-heptamethylnonane (this work). Values of V ^E are negative and similar for both series, but vary considerably with the hexane within a series. According to the theory, V ^E contains a P^* contribution not found in the excess enthalpy and entropy, which depends strongly on the internal pressures and the derived P^* parameters of the components. Values of V ^E are well predicted for both series, the variation of V ^E corresponding to the different internal pressures or P^* parameters of the hexanes.     

Analysis of the equations of state of polyolefin melts in terms of the simha-somcynsky hole theory

Pressure–volume–temperature data on melts of low-density polyethylene, polypropylene (PP), poly(butene-1) (PBT), and poly(4-methylpentene-1) (PMP) previously reported by us have been evaluated in terms of the Simha–Somcynsky hole theory of polymeric liquids by a determination of the reducing parameters P^*, V^*, and T^* for each system. Literature data on the reducing parameters of linear polyethylene and of a branched polyethylene of intermediate density are also considered. Agreement with theory is best for the polyethylenes and deteriorates markedly in the series PBT:PP:PMP. These higher polyolefins have very low values of P^*, thus suggesting a deficiency of the Simha–Somcynsky theory at high reduced pressures P? = P/P^*. In these polyolefins, systematic variations of the reducing parameters (and molecular parameters derived therefrom) are noted and discussed. Correlations found previously between T^* and the moleculer weight M₀ of the effective segment of the theory or its hard-core volume M₀V^* are obeyed by the polyethylenes only. The higher polyolefins show serious deviations from these correlations.     

The principle of corresponding states for liquid normal and branched alkanes

Prigogine's principle of corresponding states for chain-molecule liquids was tested by the determination of the characteristic volumes, temperatures, and pressures of then-alkanes from hexane through dodecane and of branched hexanes, heptanes, and octanes, using the method of Patterson and Bardin. The characteristic parameterV ^* is shown to be influenced by steric hindrance in the molecule. The quantitiesV ^* andT ^* appeared to be slightly dependent on temperature;P ^* is independent of chain length in homologous series of normal and branched alkanes.     

Relevance of cage recombination in the plastic deformation of polymers

For a polymer in which permanent rupture of individual molecules is the rate-limiting process for plastic deformation, the kinetics of chain-end diffusion and secondary radical reactions should be compared with the kinetics of caged radical recombination in the calculation of activation parameters for plastic deformation. If mechanisms of cage escape are slower than those for cage recombination, the activation parameters for plastic deformation will differ from those for the initial bond-breaking process. For the case of polyethylene deformed in the vicinity of 250°K, the critical thermally activated event appears to involve scission of the polymer molecule near the site of an abstracted hydrogen atom. For this system the dominant cage-escape mechanism is diffusion, which is faster than either hydrogen abstraction or unzipping to the monomer. However, at low stresses the rate of cage recombination is expected to be higher than the rate of cage escape, so that the activation parameters for deformation should be the sum of those for chain scission and diffusion. The contribution of diffusion (ca. 15 kcal/mole) to the activation energy for deformation (E^*, extrapolated to zero stress conditions) is relatively modest. However, the calculated molar activation volume for deformation V^* increases by almost an order of magnitude, i.e., from ca. 10 to ca. 76 cm³/mole when diffusion is required. Consideration of experimental values of E^* and V^* for high molecular weight polyethylene indicates that, in the regime examined, chain scission plus chain-end diffusion is required to effect plastic deformation.     

Volumetric and Viscometric Properties of Aqueous Solutions of N-Methylformamide, 1,2-Diaminopropane and 2-Methylpropane-2-ol

Density and viscosity of aqueous solutions of N-methylformamide (NMF), 1,2-diaminopropane (DAP) and 2-methylpropane-2-ol (MPL) have been measured precisely over the entire composition range (i.e., 1 ≥ x ₂ ≥ 0) at five equidistant temperatures ranging from 298.15 to 318.15 K. Excess molar volume (V^E _m ) and excess viscosity (η ^E ) have been calculated from measured density and viscosity data, respectively. Excess molar volume and excess viscosity have been fitted by the least squares method to the four parameters Redlich-Kister equation. The results have been interpreted on the basis of (i) interstitial incorporation, (ii) breakdown of the structure of pure liquids, (iii) hydrophobic hydration, (iv) hydrophobic interaction and (v) association between dissimilar liquids.     

Volumetric and Transport Properties of Ternary Mixtures Containing 1-Butanol or 1-Pentanol,Triethylamine and Cyclohexane at 303.15 K: Experimental Data,Correlation and Prediction by the ERAS Model

The excess molar volumes, V _m^E, viscosity deviations, Δη, and excess Gibbs energies of activation, ΔG ^*E, of viscous flow have been investigated from density and viscosity measurements for two ternary mixtures, 1-butanol + triethylamine + cyclohexane and 1-pentanol + triethylamine + cyclohexane, and corresponding binaries at 303.15 K and atmospheric pressure over the entire range of composition. The empirical equations due to Redlich-Kister, Kohler, Rastogi et al., Jacob-Fitzner, Tsao-Smith, Lark et al., Heric-Brewer, and Singh et al. have been employed to correlate V _m^E, Δη and ΔG ^*E of the ternary mixtures with their corresponding binary parameters. The results are discussed in terms of the molecular interactions between the components of the mixture. Further, the Extended Real Associated Solution, ERAS, model has been applied to V _m^E for the present binary and ternary mixtures, and the results are compared with experimental data.     

Excess Molar Volumes and Excess Partial Molar Volumes of Triethylene Glycol Monomethyl Ether–n-Alcohol Mixtures at 25°C

The excess molar volumes V ^E have been measured for binary mixtures of triethylene glycol monomethyl ether with methanol, ethanol, 1-propanol, 1-pentanol, and 1-hexanol as a function of composition using a continuous–dilution dilatometer at 25°C at atmosphere pressure. V ^E are negative over the entire range of composition for the systems triethylene glycol monomethyl ether + methanol, + ethanol, and + 1-propanol, and positive for the remaining systems, containing 1-pentanol and + 1-hexanol. V ^E increases in a positive direction with increasing carbon chain length of the n-alcohol. The excess partial molar volumes V _i ^E of the components were evaluated from the V ^E results. The behavior of V ^E and V _i ^E with composition and the number of carbon atoms in the alcohol molecule is discussed.     

Excess molar volumes,viscosity, refractive index,and Gibbs energy of activation of binary biodiesel + benzene,and biodiesel + toluene mixtures at 298.15 and 303.15 K

Excess molar volumes (V ^E), viscosities, refractive index, and Gibbs energies were evaluated for binary biodiesel + benzene and toluene mixtures at 298.15 and 303.15 K. The excess molar volumes V ^E were determined from density, while the excess Gibbs free energy of activation G*^E was calculated from viscosity deviation Δη. The excess molar volume (V ^E), viscosity deviation (Δη), and excess Gibbs energy of activation (G*^E) were fitted to the Redlich-Kister polynomial equation to derive binary coefficients and estimate the standard deviations between the experimental data and calculation results. All mixtures showed positive V ^E values obviously caused by increased physical interactions between biodiesel and the organic solvents.     

Excess Molar Volumes and Partial Molar Volumes of Dipropylene Glycol Monomethyl Ether + n-Alkanol Mixtures at 25°C

The excess molar volumes V^E for binary liquid mixtures containing dipropylene glycol monomethyl ether and methanol, ethanol, 1-propanol, 1-butanol, 1-pentanol, 1-hexanol, and 1-heptanol have been measured using a continuous dilution dilatometer over the whole mole fraction range at 25°C at atmospheric pressure. V^E are negative over the whole composition range except for the systems containing 1-pentanol, 1-hexanol, or 1-heptanol which are positve at every composition. V^E increases in a positive direction with increase in chain length of the n-alcohol. The results have been used to estimate the excess partial molar volumes V_i^E of the components. The change of V^E and V_i^E with composition and the number of carbon atoms in the alcohol molecule are discussed as a basis to understand some of the molecular interactions present in the mixtures:     

Study of Densities, Viscosities and Ultrasonic Speeds of Binary Mixtures Containing 1,2-Dimethoxyethane and an Alkan-l-ol at 298.15 K

The viscosity deviation (Δη), the excess molar volume (V ^E) and the ultrasonic speed (u) have been investigated from viscosity (η) and density (ρ ) measurements of binary liquid mixtures of 1,2-dimethyoxyethane with methanol, ethanol, propan-1-ol, butan-1-ol, pentan-1-ol, hexan-1-ol or octan-1-ol over the entire range of composition at 298.15 K. The excess volumes are negative over the entire range of composition for all of the mixtures with the exception of hexan-1-ol and octan-1-ol. The excess isentropic compressibilities (K _S ^E) and viscosity deviations are negative for all of the mixtures. The magnitudes of the negative values of V ^E decrease with the number of carbon atoms of the alkan-1-ol. The trend of increasing K _S ^E values with the chain length of the alkanol is similar to that observed in the case of V ^E. Graphs of V ^E, Δ η, K _S ^E, Δ u, L _f ^E and Z ^E against composition are presented as a basis for a qualitative discussion of the results.     

Excess Molar Volumes and Excess Logarithm Viscosities for Binary Mixtures of the Ionic Liquid 1-Butyl-3-methylimidazolium Hexaflurophosphate with Some Organic Compounds

Experimental data of densities and viscosities are presented for the mixtures of the ionic liquid 1-butyl-3-methylimidazolium hexaflurophosphate, [C₄mim][PF₆], with acetone, 2-butanone, 3-pentanone, cyclopentanone and ethyl acetate at 298.15 K. Based on these data, excess molar volumes, V_m^E, and excess logarithm viscosities, (lnη)^E, have been determined for the binaries. It is shown that all values of V_m^E are negative but those of (lnη)^E are positive. Interestingly, a minimum in V_m^E and a maximum in (lnη)^E are observed at about the same mole fraction of the ionic liquid (x = 0.3) for every mixture investigated. Combined with the V_m^E data reported in literature, the effects of the [PF₆]⁻ and [BF₄]⁻ anions are compared. The results have been discussed in terms of the ion–dipole interactions of the cations of the ionic liquids with the organic compounds as well as their influence on the association of [C₄mim]⁺ and [PF₆]⁻ in the ionic liquid.     

Viscoelasticity and birefringence of polyisoprene

The complex Young's modulus, E^*(ω), and the complex strain-optical coefficient, O^*(ω), which is the ratio of the birefringence to the strain, were measured for polyisoprene (PIP) over a frequency range of 1 ～ 130 Hz and a temperature range of 22 ～ ?100°C. The imaginary part of O^*, O″, was positive at low frequencies and negative at high frequencies. The real part, O′, was always positive and showed a maximum. The complicated behavior of O^* could be understood by the assumption that E^* = E_R^* + E_G^* and O^* = C_RE_R^* + C_GE_G^*, where E_R^* and E_G^* were complex quantities and C_R and C_G were constants. The C_R value, equal to the ordinary stress-optical coefficient measured in the rubbery plateau zone, was 2.0 × 10^?9 Pa^?1. The C_G value, defined as the ratio O″/E″ in the glassy zone, was ?1.1 × 10^?11 Pa^?1. The E_G^*, which was the major component of E^* in the glassy zone, showed almost the same frequency dependence as that of polystyrene and polycarbonate. The E_R^*, which was dominant in the rubbery zone, was described well by the bead-spring theory. The temperature dependence of the E_G^* was stronger than that of the E_R^*. This difference caused the breakdown of the thermorheological simplicity for E^* and O^* around the glass-to-rubber transition zone. © 1995 John Wiley & Sons, Inc.     

Molecular Interactions in Formamide + Isomeric Butanols: An Ultrasonic and Volumetric Study

Densities, , ultrasonic speeds, u and viscosities, of the binary mixtures of formamide (FA) with 1-butanol, 2-methyl-1-propanol, and 2-methyl-2-propanol, including those of pure liquids, were measured over the whole composition range at 35°C. Using the experimental values of , u and , the deviations in isentropic compressibility, _s , excess volume, V ^E, viscosity, , and excess Gibbs energy of activation of viscous flow, G* ^E , were calculated from the linear dependence of these parameters on composition of mixtures. The apparent molar isentropic compressibility, K _,2 and apparent molar volume, V ^,2 of alcohols in FA were also calculated. The variations of these parameters with composition are discussed from the point of view of intermolecular interactions in these mixtures. The V ^E data have also been analyzed using Prigogine–Flory–Patterson theory. An analysis of each of the three contributions, viz., interactional, free volume, and P* effect to V ^E shows that P*, the internal pressure parameter of the theory, plays a dominant role in deciding the sign and magnitude of V ^E.     

Simulation study on the coil‐globule transition of adsorbed polymers

Coil‐globule transition of adsorbed polymers on attractive surface is simulated by using dynamic Monte Carlo simulation. The effect of surface attraction strength E_PS and intrachain attraction strength E_PP on polymer phases is investigated. The coil‐globule transition point is dependent on E_PS, while the globule conformation is dependent on both E_PS and E_PP. At small E_PS, the conformation of adsorbed polymer is three‐dimensional layer structure. While at large E_PS, the conformation of adsorbed polymer is roughly two‐dimensional (2D) at E_PP = 0, and we observe a 2D coil‐globule transition at E*_PP and a layer‐forming transition from 2D conformation to three‐dimensional layer structure at E*_PP,L > E*_PP. The layer‐forming transition point E*_PP,L increases with E_PS as E*_PP,L = E_PS ? 1.4. In addition, we find that the adsorption suppresses the coil‐globule transition, i.e., the coil‐globule transition point E*_PP increases with the increase in E_PS. © 2016 Wiley Periodicals, Inc. J. Polym. Sci., Part B: Polym. Phys. 2016 , 54, 2359–2367     

Thermodynamics of Mixtures with Strongly Negative Deviations from Raoult's Law. VII. Excess Molar Volumes at 25°C for 1-Alkanol + N-Methylbutylamine Systems—Characterization in Terms of the ERAS Model

Excess molar volumes, V ^E _m, at 25^°C and atmospheric pressure, over the entire composition range for binary mixtures of methanol, ethanol, 1-propanol, 1-butanol, 1-pentanol, 1-hexanol, 1-heptanol, and 1-octanol with-methylbutylamine are reported. They are calculated from densities measured with a vibrating-tube densimeter. All the excess volumes are large and negative over the entire composition range. This indicates strong interactions between unlike molecules, which are greatest for the system involving methanol, characterized by the most negative V ^E _m. For the other solutions, V ^E _m at equimolar composition, is approximately the same. The V ^E _m curves vs. mole fraction are nearly symmetrical. The ERAS model is applied to 1-alkanol + N-methylbutylamine, and 1-alkanol + diethylamine systems. The ERAS parameters confirm that the strongest interactions between unlike molecules are encountered in solutions with methanol. The model consistently describes V ^E _m and excess molar enthalpies H ^E _m of the mixtures studied.     

Excess enthalpy and excess volume for binary systems of two ionic liquids + water

In this work we report the experimental measurements of excess molar enthalpy and excess molar volume, at 298.15 K and atmospheric pressure, on ethylammonium nitrate (EAN) and propylammonium nitrate (PAN) + water mixtures. Positive enthalpies were found for the two systems (maximum, at x ₁ around 0.37 correspond to about 700 and 900 J mol⁻¹ for EAN and PAN respectively). As the hydrophobic/hydrophilic ratio increases, along with the length of the alkyl chain in the ionic liquids, ILs, the specific interactions IL-water become less important. The excess molar volumes, V ^E, are negative over the entire composition range for the two binary mixtures. They have similar values but curves exhibit a different asymmetric shape and around equimolar composition they intersect each other. This behaviour: positive H ^E and negative V ^E, is not very common.     

The effect of pressure on order destruction and order creation in linear or branched alkane mixtures

The pressure dependence of the excess enthalpy H ^E , dH ^E /dP, has been calculated from experimental excess volumes V ^E and dV ^E /dT using dH ^E /dP=V ^E –TdV ^E /dT. dH ^E /dP at zero pressure are reported at 25°C and equimolar concentration for the mixtures: cyclohexane with the series of normal alkanes (n-C _n , where n=6,8,10,12,14 and 16) and with the series of highly branched alkanes (br-C _n , where n=6,8,12 and 16), benzene, toluene and p-xylene +n-C _n and 1-chloronaphthalene +n-C _n and br-C _n . Experimental and Flory theory dH ^E /dP values are in good agreement for the whole cyclohexane +br-C _n series. For the n-C _n series, dH ^E /dP becomes increasingly positive deviating from the Flory predictions. This discrepancy is due to the presence of short-range orientational order in the higher n-C _n pure liquids which makes dH/dP more negative and which, upon mixing, is destroyed producing a positive contribution to dH ^E /dP not accounted for by the theory. The discrepancy between theoretical and experimental dH ^E /dP is large for benzene, but progressively smaller for toluene, p-xylene and 1-chloronaphthalene. These results are consistent with creation of order between the aromatic plate-like molecule and the long n-C _n in solution. For 1-chloronaphthalene +n-C _n , this order creation process produces a negative contribution to dH ^E /dP which balances the positive order-destruction contribution originated by the rupture, upon mixing, of short-range orientational order in pure n-C _n .     

Excess Molar Volumes, Excess Viscosities and Ultrasonic Speeds of Sound of Binary Mixtures of 1,2-Dimethoxyethane with Some Aromatic Liquids at 298.15 K

Densities, viscosities and ultrasonic speeds of sound for binary mixtures of 1,2-dimethoxyethane (DME) with benzene, toluene, chlorobenzene, benzyl chloride, benzaldehyde, nitrobenzene, and aniline are reported over the entire composition range at ambient pressure and temperature (i.e., T=298.15 K and p=1.01×10⁵ Pa). These experimental data were utilized to derive the excess molar volumes (V_m^EV_{\mathrm{m}}^{\mathrm{E}}), excess viscosities (η ^E), and various acoustic parameters including the deviation in isentropic compressibility (Δκ _S ), internal pressure (π _I), and excess enthalpy (H ^E). From the excess molar volumes (V_m^EV_{\mathrm{m}}^{\mathrm{E}}), the excess partial molar volumes ([`(V)]<sub>m,1</sub><sup>E</sup>\overline{V}_{\mathrm{m},1}^{\mathrm{E}} and [`(V)]_m,2^E\overline{V}_{\mathrm{m},2}^{\mathrm{E}}) and excess partial molar volumes at infinite dilution ([`(V)]<sub>m,1</sub><sup>0,E</sup>\overline{V}_{\mathrm{m},1}^{0,\mathrm{E}} and [`(V)]_m,2^0,E\overline{V}_{\mathrm{m},2}^{0,\mathrm{E}}) were derived and discussed for each liquid component in the mixtures. The excess/deviation properties were found to be either negative or positive, depending on the molecular interactions and the nature of the liquid mixtures.     

Pressure dependence of dielectric properties of chlorinated polyethylene vulcanizate. II. Free volume and configurational entropy theories

The P–V–T relation and the heat capacity of a chlorinated polyethylene vulcanizate were measured. Several tests on the validity of thermodynamic treatments of the α relaxation process and the glass-transition temperature were performed by using dielectric properties. From a study using excess variables, it was shown that the entropy theories represented by the equations of Goldstein and Adam–Gibbs' were slightly better than the free volume theory represented by Doolittle's equation. However the study provided no distinction between the two entropy theories. Some tests were also performed on the pressure dependence of the glass-transition temperature, dT_g/dP, and on H^*_V/H^*_V where H^*_V is the isochoric activation enthalpy and H^*_P is the isobaric activation enthalpy. Here, too, the entropy theories were better than the free volume theory. Goldstein's expression gave values of both dT_g/dP and H^*_V/H^*_P closest to those from the dielectric experiments. The Adam–Gibbs' equation gave a temperature dependence for dT_g/dP and H^*_V/H^*_P most similar to those from the experiments.     

Excess Molar Volumes of Binary Mixtures of 1-Heptanol or 1-Nonanol with n-Polyethers at 25°C

Excess molar volumes V ^E _m at 25°C and atmospheric pressure over the entirecomposition range for binary mixtures of 1-heptanol with 2,5-dioxahexane, 2,5,8-trioxanonane,5,8,11-trioxapentadecane, 2,5,8,11-tetraoxadodecane,or 2,5,8,11,14-pentaoxapentadecane, and mixtures of 1-nonanol with 2,5-dioxahexane,3,6-dioxaoctane, 2,5,8-trioxanonane, 3,6,9-trioxaundecane, 5,8,11-trioxapentadecane,2,5,8,11-tetraoxadodecane, or 2,5,8,11,14-pentaoxapentadecane are reportedfrom densities measured with a vibrating-tube densimeter.V ^E _m curves are nearlysymmetrical at about 0.5 mole fraction. Excess molar volumes are usually positive,indicating predominance of positive contributions to V ^E _m from the disruption ofH bonds of alcohols and from physical interactions. When chain lengths ofboth components of the mixture are increased, the contribution from interstitialaccommodation appears to be sufficiently negative, such that V ^E _m becomes negative(e.g., l-nonanol + 5,8,11-tetraoxapentadecane).