Differential Thermal Analysis under Pressure on Cyanocyclohexane, 1,2,3,4-Tetrahydro-5,6-dimethyl-1,4-methanonaphthalene, and 2-Methyl-2-propanol

Reuter, J.; Brückert, T.; Würflinger, A.

doi:10.1515/zna-1993-5-622

Cited by 8 publications

(9 citation statements)

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“…Although many different thermal treatments have been employed, it was not pos- sible to observe the crystallization at normal pressure. Obviously high pressure favours the transformation to the crystal phase that has also been observed in previous studies on disordered molecular crystals [8].…”

Section: Butyl-thiocyanobiphenyl (4tcb)supporting

confidence: 80%

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High-pressure DTA Studies of the Phase Behaviors of 4-n -butyl-thiocyanobiphenyl (4TCB) and 4-w-pentyl-4’-n-phenyl-cyanocyclohexane (5HCP)

Massalska-Arodź

Würflinger

Büsinga

1999

Zeitschrift Für Naturforschung A

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DTA measurements of 4-/i-butyl-thiocyanobiphenyl (4TCB) and/?-cyano-/?'-pentylphenyl-cyclohexane (5HCP) have been performed in the temperature range 220 K-390 K and pressures up to 400 MPa. For 4TCP a transition from a crystalline to a liquid crystal phase (probably smectic E) could be detected at higher pressures > 90 MPa. The pressure dependence of the transition temperature has been established. At pressures lower than 88.7 MPa no transition of SmE into a crystal or into a glass has been found. For 5HCP only the melting curve was observed, in contrast to 5PCH, which displays a liquid crystalline nematic phase.

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Section: Butyl-thiocyanobiphenyl (4tcb)supporting

confidence: 80%

“…at the clearing point AT/Ap -0.4 K/MPa is larger than that at melting AT/Ap =0.3 K/MPa [2,3]. The values AT/Ap observed for liquid crystals at melting seems not to differ much from those observed for some plastic crystals [3,7,8],…”

Section: Butyl-thiocyanobiphenyl (4tcb)mentioning

confidence: 65%

High-pressure DTA Studies of the Phase Behaviors of 4-n -butyl-thiocyanobiphenyl (4TCB) and 4-w-pentyl-4’-n-phenyl-cyanocyclohexane (5HCP)

Massalska-Arodź

Würflinger

Büsinga

1999

Zeitschrift Für Naturforschung A

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“…From measurements of the viscosities, a T 0 of (192 ( 5) K was obtained. These T 0 values correspond to a glass-transition temperature T g of 188 K at atmospheric pressure observed by Reuter et al 43 from differential thermal analyses. 5,6-Me 2 THMN has to be classified as a "fragile" organic glass-forming liquid because of its intermolecular interactions and the temperature dependence of its reorientational motion and viscosities.…”

Section: Resultssupporting

confidence: 70%

Reorientational Dynamics of the Model Compound 1,2,3,4-Tetrahydro-5,6-dimethyl- 1,4-methanonaphthalene in Neat Liquid from Temperature-Dependent ¹³C Nuclear Magnetic Relaxation Data: Spectral Densities and Correlation Functions

Dölle

2002

J. Phys. Chem. A

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The reorientational motion of the hydrocarbon 1,2,3,4-tetrahydro-5,6-dimethyl-1,4-methanonaphthalene (5,6-Me 2 THMN) was studied over a wide range of temperature by the evaluation of 13 C spin-lattice relaxation rates and NOE factors. The data from measurements at 22.63, 75.47, and 100.62 MHz were fitted to spectral densities introduced by Bloembergen, Purcell and Pound (1948), Davidson and Cole (1951), and for the first time, by a new spectral density derived from a Tricomi correlation function recently introduced by Zeidler (1991). For the temperature dependence of the correlation times, a Vogel-Fulcher-Tammann equation was applied. To obtain a reasonable fit with either Bloembergen-Purcell-Pound or Cole-Davidson spectral densities, it was necessary to apply the generalized order parameter from the approach by Lipari and Szabo (1982). The same quality of fit was achieved by the use of the Tricomi spectral density, although in this case it was not necessary to employ the Lipari-Szabo approach.

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“…On further cooling a glass transition appears at approximately 135 K as proven by calorimetry and dielectric spectroscopy. 8,[34][35][36][37][38] An additional, small heat-capacity jump 39 also appears at around 55 K, which has been attributed to the freezing of the interconversion between the axial and equatorial conformers. 40 A stable low-temperature phase II results by annealing of phase I.…”

Section: Introductionmentioning

confidence: 99%

Effects of internal molecular degrees of freedom on the thermal conductivity of some glasses and disordered crystals

et al. 2012

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The thermal conductivity κ(T ) of the fully ordered stable phase II, the metastable phase III, the orientationally disordered (plastic) phase I, as well as the nonergodic orientational glass (OG) phase, of the glass former cyclohexanol (C 6 H 11 OH) has been measured under equilibrium vapor pressure within the 2-200 K temperature range. The main emphasis is here focused on the influence of the conformational disorder upon the thermal properties of this material. Comparison of results with those regarding cyanoclyclohexane (C 6 H 11 CN), a chemically related compound, serves to quantify the role played by the terminal groups -OH and -CN on the phonon scattering processes. The picture that emerges shows that motions of such groups do play a minor role as scattering centers, both within the low-temperature orientationally ordered phases as well as in the OG states. The results are analyzed within the Debye-Peierls relaxation time model for isotropic solids comprising mechanisms for long-wave phonon scattering within the OG and orientational ordered low-temperature phases, as well as others arising from localized short-wavelength vibrational modes as pictured by the Cahill-Pohl model. By means of complementary neutron and Raman scattering we show that in the OG state the energy landscapes for both compounds are very similar.

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Differential Thermal Analysis under Pressure on Cyanocyclohexane, 1,2,3,4-Tetrahydro-5,6-dimethyl-1,4-methanonaphthalene, and 2-Methyl-2-propanol

Cited by 8 publications

References 0 publications

High-pressure DTA Studies of the Phase Behaviors of 4-n -butyl-thiocyanobiphenyl (4TCB) and 4-w-pentyl-4’-n-phenyl-cyanocyclohexane (5HCP)

High-pressure DTA Studies of the Phase Behaviors of 4-n -butyl-thiocyanobiphenyl (4TCB) and 4-w-pentyl-4’-n-phenyl-cyanocyclohexane (5HCP)

Reorientational Dynamics of the Model Compound 1,2,3,4-Tetrahydro-5,6-dimethyl- 1,4-methanonaphthalene in Neat Liquid from Temperature-Dependent ¹³C Nuclear Magnetic Relaxation Data: Spectral Densities and Correlation Functions

Effects of internal molecular degrees of freedom on the thermal conductivity of some glasses and disordered crystals

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Differential Thermal Analysis under Pressure on Cyanocyclohexane, 1,2,3,4-Tetrahydro-5,6-dimethyl-1,4-methanonaphthalene, and 2-Methyl-2-propanol

Cited by 8 publications

References 0 publications

High-pressure DTA Studies of the Phase Behaviors of 4-n -butyl-thiocyanobiphenyl (4TCB) and 4-w-pentyl-4’-n-phenyl-cyanocyclohexane (5HCP)

High-pressure DTA Studies of the Phase Behaviors of 4-n -butyl-thiocyanobiphenyl (4TCB) and 4-w-pentyl-4’-n-phenyl-cyanocyclohexane (5HCP)

Reorientational Dynamics of the Model Compound 1,2,3,4-Tetrahydro-5,6-dimethyl- 1,4-methanonaphthalene in Neat Liquid from Temperature-Dependent 13C Nuclear Magnetic Relaxation Data: Spectral Densities and Correlation Functions

Effects of internal molecular degrees of freedom on the thermal conductivity of some glasses and disordered crystals

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Reorientational Dynamics of the Model Compound 1,2,3,4-Tetrahydro-5,6-dimethyl- 1,4-methanonaphthalene in Neat Liquid from Temperature-Dependent ¹³C Nuclear Magnetic Relaxation Data: Spectral Densities and Correlation Functions