Thermodynamics of n‐alkanes

Schaerer, A. A.; Bayle, Gérard; Mazee, W. M.

doi:10.1002/recl.19560750505

Cited by 11 publications

(6 citation statements)

References 5 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Values for the latter are in fair agreement with those of Schaerer et al, 17,18 but the solid-state transition temperatures are, with the exception of C22H46, below their values. With the exception of c18H38, thermograms from differential thermal analyses showed that upon warming, each compound underwent a solid-state transition P-fa several degrees below its a m.p.…”

supporting

confidence: 86%

“…With the exception of c18H38, thermograms from differential thermal analyses showed that upon warming, each compound underwent a solid-state transition P-fa several degrees below its a m.p. Values for the latter are in fair agreement with those of Schaerer et al, 17,18 but the solid-state transition temperatures are, with the exception of C22H46, below their values. These discrepancies show the presence of impurities.…”

supporting

confidence: 86%

See 1 more Smart Citation

Heterogeneous and homogeneous nucleation in supercooled triglycerides and n-paraffins

Phipps¹

1964

Trans. Faraday Soc.

View full text Add to dashboard Cite

The supercooling and freezing of aqueous suspensions of droplets of a series of saturated triglycerides and n-paraffins have been studied. For all compounds the relation between the logarithm of the diameter of a drop and its mean freezing temperature is linear, which suggests that heterogeneous nucleation was commonly the underlying freezing mechanism. For each compound, a critical temperature Ts identifying maximum supercooling was established. Near this critical threshold, freezing was independent of droplet diameter over a small range of the latter. This is considered to be good evidence for the occurrence of spontaneous or homogeneous nucleation. The reduced temperature Ts/T,,,, where T, is the bulk melting point of the nucleated crystals, is 0.920 for tristearin and 0.933 for tri-palmitin, -myristin and -1aurin. Values for the hydrocarbons examined (c18H38, c26H54, C3&62, C34H70) range from 0.932 to 0.970. Two ways of interpreting the critical supercooling data are discussed and crystal-melt interfacial free energies derived for both cases. In the one method, Turnbull and Fisher's equation is used with an assumed value for the nucleation frequency, while in the other, Buckle's analysis is followed in which a nucleation time lag is recognized.* This work is based upon part of a

show abstract

supporting

confidence: 86%

supporting

confidence: 86%

Heterogeneous and homogeneous nucleation in supercooled triglycerides and n-paraffins

Phipps¹

1964

Trans. Faraday Soc.

View full text Add to dashboard Cite

show abstract

“…The critical temperature (Tc) is determined by the first and the second term of eq 6 U TC = ~J (9) Below this temperature, the first-order phase transition of the chains takes place at Tt where H(T,) is equal to zero. But these temperatures are shifted by the other terms, Gh+i and U.…”

Section: Model and Expression Of The Gibbs Free Energymentioning

confidence: 99%

“…Both experimental and theoretical studies on this phase ® Abstract published in Advance ACS Abstracts, June 1, 1994. 0022-3654/94/2098-6187S04.50/0 transition of n-paraffin chains have been extensively done. [8][9][10][11] Kobayashi calculated the lattice energy in details and succeeded to explain the latent heat at the release of rotational motion of each length of hydrocarbon chains.10 These results are helpful for us to make our calculations on the coagel-gel phase transition.…”

Section: Introductionmentioning

confidence: 99%

Statistical Mechanical Theory of the Coagel-Gel Phase Transition in Ionic Surfactant/Water Systems

Tsuchiya¹,

Tsujii²,

Maki³

et al. 1994

J. Phys. Chem.

View full text Add to dashboard Cite

Some ionic surfactant/water systems undergo the coagel-gel phase transition. Both coagel and gel phases consist of alternating layers of bilayer membranes of surfactants and water. The hydrocarbon chains are in a crystalline state, and thickness of water layer is in the order of 10 A in the coagel phase. Upon the transition from coagel to gel, the hydrocarbon chains become able to rotate around the chain axis, and the thickness of water layer discontinuously increases to the order of 1000 A. We present a statistical mechanical theory to explain this phase transition. The mean field Gibbs free energy of the system is written as a function of three-order parameters which are concerned with the rotational motion of the hydrocarbon chains, the degree of dissociation of counterions of the surfactant molecules, and the distance between neighboring membranes.The area occupied by one hydrophilic head group on the membrane surface in the rotating state of the hydrocarbon chain is assumed to be larger than that in its fixed state. The theory successfully explains the order4isorder phase transition of the hydrocarbon chains and the simultaneous separation of bilayer membranes. The expansion in the area of one molecule leads to a coupling between three-order parameters. The theoretical calculation predicts that the strength of this coupling results in the three types of phase transition: (1) coagel/gel phase transition, (2) pseudogel (the hydrocarbon chains are in crystalline state, and the membranes separate)/gel phase transition, (3) coagel/pseudocoagel (the rotation of hydrocarbon chains around the chain axis is released, and the membranes do not separate) phase transition.

show abstract

“…Because of the importance of the n -alkanes (hereafter denoted by C n ), numerous studies − have been carried out to determine their thermodynamic properties and their structural behavior. Although numerous values of the temperatures and enthalpies of solid−solid and solid−liquid transitions of C n 's are available ...…”

Section: Introductionmentioning

confidence: 99%

Experimental Enthalpy Increments from the Solid Phases to the Liquid Phase of Homologous n-Alkane Series (C₁₈ to C₃₈ and C₄₁, C₄₄, C₄₆, C₅₀, C₅₄, and C₆₀)

Briard¹,

Bouroukba²,

Petitjean³

et al. 2003

J. Chem. Eng. Data

View full text Add to dashboard Cite

Measurements of enthalpy increments from the temperature of the ordered phases of low temperatures at 293.4 K and 298.3 K up to the liquid phase above the melting point were carried out by differential scanning calorimetry using a discontinuous mode of temperature programming on the n-alkanes from C 18 to C 38 and C 41 , C 44 , C 46 , C 50 , C 54 , and C 60 . The temperatures and enthalpies of the solid-solid transitions and of the fusion were also determined and compared with the values of the literature.

show abstract

Thermodynamics of n‐alkanes

Cited by 11 publications

References 5 publications

Heterogeneous and homogeneous nucleation in supercooled triglycerides and n-paraffins

Heterogeneous and homogeneous nucleation in supercooled triglycerides and n-paraffins

Statistical Mechanical Theory of the Coagel-Gel Phase Transition in Ionic Surfactant/Water Systems

Experimental Enthalpy Increments from the Solid Phases to the Liquid Phase of Homologous n-Alkane Series (C₁₈ to C₃₈ and C₄₁, C₄₄, C₄₆, C₅₀, C₅₄, and C₆₀)

Contact Info

Product

Resources

About

Thermodynamics of n‐alkanes

Cited by 11 publications

References 5 publications

Heterogeneous and homogeneous nucleation in supercooled triglycerides and n-paraffins

Heterogeneous and homogeneous nucleation in supercooled triglycerides and n-paraffins

Statistical Mechanical Theory of the Coagel-Gel Phase Transition in Ionic Surfactant/Water Systems

Experimental Enthalpy Increments from the Solid Phases to the Liquid Phase of Homologous n-Alkane Series (C18 to C38 and C41, C44, C46, C50, C54, and C60)

Contact Info

Product

Resources

About

Experimental Enthalpy Increments from the Solid Phases to the Liquid Phase of Homologous n-Alkane Series (C₁₈ to C₃₈ and C₄₁, C₄₄, C₄₆, C₅₀, C₅₄, and C₆₀)