Dielectric relaxation in supercooled triphenylchloromethane and intrinsic factor determining mobility in molecular liquids

Naoki, Motosuke; Seki, Masumi; Kugo, Hiroaki; Sanda, Fumio; Tanioka, Toshiya

doi:10.1021/j100167a048

Cited by 14 publications

(5 citation statements)

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“…(Recall that we are taking the difference between the C p (measured) and extrapolated C p (glass), which are equal below T g .) However, it is well-known that an excess configurational entropy exists below T g 45 and is usually found for crystallizable liquids, since an account is able to be made for Δ S f . − Since we cannot acquire this quantity, we must approximate by adjusting the DSC obtained S c by the addition of a constant value, S c (0), given in Table , by best fitting the DSC S c region T g + 10 K < T < T g + 60 K to the Alegria model of eq 7. A very good agreement is found between the vertically shifted calorimetric values and the model of eq 7, as shown in Figure .…”

Section: Resultsmentioning

confidence: 99%

Molecular Dynamics in Cyanate Ester Resin Networks and Model Cyanurate Compounds

Fitz¹,

Mijović²

2000

Macromolecules

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Molecular dynamics via broad-band dielectric relaxation spectroscopy (DRS) are obtained on a class 3 network-forming system: a generic cyanate ester resin. The potential for in-situ monitoring of the network-forming reaction is explored. The segmental dynamics of the growing network are investigated, and a hitherto unknown secondary relaxation process, β*, is found. This relaxation is distinctly different from the Johari-Goldstein slow β process. Model compounds and conformational strain analysis are used to elucidate the β* relaxation molecular mechanism. The R process in selected cyanate networks was analyzed with the Adam-Gibbs thermodynamics-based relations (AG model). The AG model provides a link between the relaxation time of a cooperatively rearranging domain (CRD) and configurational entropy. The model is explored via DRS and calorimetrically for various network structures. A good agreement is found between independent quantities derived from both techniques when examined in the AG framework. These results lend support to the CRD concept used in the AG model and, more generally, toward the establishment of the heterogeneous view of relaxations in glass-formers.

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Section: Resultsmentioning

confidence: 99%

Molecular Dynamics in Cyanate Ester Resin Networks and Model Cyanurate Compounds

Fitz¹,

Mijović²

2000

Macromolecules

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“…An important issue related to the concept of fragility is the understanding of the behavior of this property under pressure. [16][17][18] Although investigation of glass forming liquids under high compression can provide new and valuable information [16][17][18][19][20][21][22][23][24][25][26][27][28][29][30][31][32] on relaxation dynamics, there is still not enough experimental results. Some strong liquids can become more fragile under high hydrostatic pressure, which can be related to their polymorphism.…”

Section: Introductionmentioning

confidence: 99%

Does fragility depend on pressure? A dynamic light scattering study of a fragile glass-former

Paluch

Gapiński

Patkowski

et al. 2001

The Journal of Chemical Physics

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Relaxation times of the ␣-process in the fragile glass-forming liquid diglycidyl ether of bisphenol-A ͑EPON 828͒ were measured in a broad pressure ͑1-1500 bar͒ and temperature ͑264-293 K͒ ranges by means of the depolarized dynamic light scattering-photon correlation spectroscopy. Based on this experimental data the fragility of the supercooled liquid was calculated in two ways: as a steepness index m of the ''Angell plot'' and as the D T-parameter from the Vogel-Fulcher-Tammann Law, and was studied as a function of pressure. It was found, that while the steepness index depends on pressure, the D T parameter is pressure independent. The pressure dependence of the glass transition temperature T g in EPON 828 was found to be nonlinear. Additionally, we established a relationship between the steepness index m T , the activation volume ⌬V # , and the coefficient ‫ץ‬T g ‫ץ/‬ P g. In this pressure dependent study we found that also for EPON 828 the nonexponentiality of the correlation function of the ␣-process correlates well with the non-Arrhenius behavior ͑steepness index͒ of the relaxation times. An equation of state describing the temperature and pressure dependence of the structural relaxation time was proposed and verified using experimental data.

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“…Dielectric relaxation of supercooled liquids at elevated pressures has been extensively investigated by Naoki and co-workers [21][22][23]. The dynamical properties of glass-forming liquids have been analysed in terms of activation variables and configurational quantities.…”

Section: Introductionmentioning

confidence: 99%

On the isothermal pressure behaviour of the relaxation times for supercooled glass-forming liquids

Paluch¹,

Rzoska²,

Habdas³

et al. 1998

J. Phys.: Condens. Matter

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This paper discusses the isothermal pressure behaviour of the relaxation times for supercooled glass-forming liquids. Analysis based on reference data and the authors' measurements of dielectric relaxation is carried out for both strong and fragile glass formers. All of the experimental relaxation times clearly exhibit a non-Arrhenius behaviour well reproduced by a function τ = τ 0p exp(C p P /(P 0 − P )) or τ = τ 0 exp(CP 0 /(P 0 − P )), giving the same estimates of the ideal glass transition pressure P 0 . Experimental data indicate that fragile materials show a more rapid increase of the relaxation time with rise of pressure than the strong ones.

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Dielectric relaxation in supercooled triphenylchloromethane and intrinsic factor determining mobility in molecular liquids

Cited by 14 publications

References 0 publications

Molecular Dynamics in Cyanate Ester Resin Networks and Model Cyanurate Compounds

Molecular Dynamics in Cyanate Ester Resin Networks and Model Cyanurate Compounds

Does fragility depend on pressure? A dynamic light scattering study of a fragile glass-former

On the isothermal pressure behaviour of the relaxation times for supercooled glass-forming liquids

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