Test of the entropy basis of the Vogel-Tammann-Fulcher equation. Dielectric relaxation of polyalcohols near Tg

Angell, C. A.; Smith, D.L.

doi:10.1021/j100216a028

Cited by 217 publications

(111 citation statements)

References 7 publications

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“…There have been a number of detailed discussions concerning the relationship between T 0 and Tfc, the Kauzmann temperature. 15 suggests that B reflects the structure of the material and this would be consistent with the theory since B comprises terms such as the defect-defect correlation length, the defect density, and the defect barrier.…”

Section: Discussionsupporting

confidence: 61%

A New Vogel-Like Law: Ionic Conductivity, Dielectric Relaxation, and Viscosity near the Glass Transition

2001

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REPORT DOCUMENTATION PAGE FUNDING NUMBERSGrant number: N00014D1AF00002'PR Number: 01PR02263-00 PERFORMING ORGANIZATION NAME(S) ANO ADORESS(ES)United States Naval Academy Physics Department Annapolis, MD 21402. PERFORMING ORGANIZATION REPORT NUMBER 29 SPONSORING/MONITORING AGENCY NAME(S) AND ADDRESS(ES)Office of SUPPLEMENTARY NOTES Prepared for publication in Physical Review Letters 12». DISTRIBUTION/AVAILABILITY STATEMENTReproduction in whole or in part is permitted for any purpose of the United States Government. This document has been approved for public release and sale, its distribution is unlimited. 12b. DISTRIBUTION CODE ABSTRACT [Maximum 200 wordjjA model, based on defect diffusion, is developed that describes temperature and pressure dependence of dielectric relaxation, ionic conductivity and viscosity of glass-forming liquids near the glass transition temperature. The resultant expressions for ionic conductivity are compared with experimental results for the polymer electrolytes poly(ethylene glycol) (PEG) and polypropylene glycol) (PPG) containing LiCF 3 S0 3 . Those for dielectric relaxation are compared with experimental results for polypropylene oxide) (PPO) and poly(vinyl acetate). The theoretical viscosity law is compared to experiments on propylene carbonate (PC). SUBJECT TERMSIonic Conductivity, Dielectric Relaxation, Viscosity, High Pressure, Theory, Experiment. The theoretical viscosity law is compared to experiments on propylene carbonate (PC).

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Section: Discussionsupporting

confidence: 61%

A New Vogel-Like Law: Ionic Conductivity, Dielectric Relaxation, and Viscosity near the Glass Transition

2001

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“…C [44]. In addition, similar plateau behavior and magnitudes for specific heat and thermal conductivity are observed for a range of tissues [34], again highlighting the value of ultrasound gel as a cryogenic tissue phantom.…”

Section: Resultssupporting

confidence: 52%

Methods for Characterizing Convective Cryoprobe Heat Transfer in Ultrasound Gel Phantoms

Etheridge

Choi

Ramadhyani³

et al. 2013

Journal of Biomechanical Engineering

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While cryosurgery has proven capable in treating of a variety of conditions, it has met with some resistance among physicians, in part due to shortcomings in the ability to predict treatment outcomes. Here we attempt to address several key issues related to predictive modeling by demonstrating methods for accurately characterizing heat transfer from cryoprobes, report temperature dependent thermal properties for ultrasound gel (a convenient tissue phantom) down to cryogenic temperatures, and demonstrate the ability of convective exchange heat transfer boundary conditions to accurately describe freezing in the case of single and multiple interacting cryoprobe(s). Temperature dependent changes in the specific heat and thermal conductivity for ultrasound gel are reported down to À150 C for the first time here and these data were used to accurately describe freezing in ultrasound gel in subsequent modeling. Freezing around a single and two interacting cryoprobe(s) was characterized in the ultrasound gel phantom by mapping the temperature in and around the "iceball" with carefully placed thermocouple arrays. These experimental data were fit with finite-element modeling in COMSOL Multiphysics, which was used to investigate the sensitivity and effectiveness of convective boundary conditions in describing heat transfer from the cryoprobes. Heat transfer at the probe tip was described in terms of a convective coefficient and the cryogen temperature. While model accuracy depended strongly on spatial (i.e., along the exchange surface) variation in the convective coefficient, it was much less sensitive to spatial and transient variations in the cryogen temperature parameter. The optimized fit, convective exchange conditions for the single-probe case also provided close agreement with the experimental data for the case of two interacting cryoprobes, suggesting that this basic characterization and modeling approach can be extended to accurately describe more complicated, multiprobe freezing geometries. Accurately characterizing cryoprobe behavior in phantoms requires detailed knowledge of the freezing medium's properties throughout the range of expected temperatures and an appropriate description of the heat transfer across the probe's exchange surfaces. Here we demonstrate that convective exchange boundary conditions provide an accurate and versatile description of heat transfer from cryoprobes, offering potential advantages over the traditional constant surface heat flux and constant surface temperature descriptions. In addition, although this study was conducted on Joule-Thomson type cryoprobes, the general methodologies should extend to any probe that is based on convective exchange with a cryogenic fluid. [DOI: 10.1115/1.4023237] Keywords: cryosurgery, cryotherapy, cryoablation, thermal properties, heat transfer modeling, clinical modeling IntroductionCryosurgery is a minimally invasive technique in which freezing temperatures are used to destroy tissue in the body to treat various conditions, including cancer (prosta...

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“…To explain their observations, Mikosch and Rice suggested that at high viscosities the solvent molecules would form transient cavities through hydrogen bonding. 15,16 The time scale for motion of the liquid ''cage'' would be comparable to or even larger than the Perrin-Stokes-Einstein orientational relaxation time, so a dye molecule could rotate in its cage relatively unperturbed by the liquid. As a result, the orientational relaxation time or at high viscosity would be lower than expected.…”

Section: Resultsmentioning

confidence: 99%

“…12, 13 Mikosch et al, 12 and Rice and Kenney-Wallace 13 proposed that the solvent may form transient cavities due to strong hydrogen bonding interactions. 15,16 The motion of the probe molecules would not be viscously damped but the probe molecules would rotate through large angular steps determined by interactions with the solvent molecules in the nearest neighbor shell. Hence the hydrodynamic properties of the solvent would be of little importance.…”

Section: Introductionmentioning

confidence: 99%

Orientational relaxation times of rhodamine 700 in glycerol-water mixtures

Megens¹,

Sprik²,

Wegdam³

et al. 1997

The Journal of Chemical Physics

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We determined orientational relaxation times for rhodamine 700 dye in glycerol-water mixtures using time-resolved fluorescence depolarization. It appears that the orientational relaxation time varies linearly with the viscosity of the solvent between 1 and 60 cP, in accordance with the Perrin-Stokes-Einstein model with stick boundary conditions. Previously others have found that for two anionic dyes in glycerol-water and a cationic dye in glycerol-ethylene glycol mixtures, the orientational relaxation time becomes less sensitive to the viscosity at very high viscosities (Ͼ25 cP at least͒. We discuss the influence of dye and solvent on the relation between orientational relaxation time and viscosity, which suggests that the relaxation time as a function of viscosity can be scaled on a common curve.

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Test of the entropy basis of the Vogel-Tammann-Fulcher equation. Dielectric relaxation of polyalcohols near Tg

Cited by 217 publications

References 7 publications

A New Vogel-Like Law: Ionic Conductivity, Dielectric Relaxation, and Viscosity near the Glass Transition

A New Vogel-Like Law: Ionic Conductivity, Dielectric Relaxation, and Viscosity near the Glass Transition

Methods for Characterizing Convective Cryoprobe Heat Transfer in Ultrasound Gel Phantoms

Orientational relaxation times of rhodamine 700 in glycerol-water mixtures

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