scholarly journals On the temperature dependence of the nonexponentiality in glass-forming liquids

2009 ◽  
Vol 130 (12) ◽  
pp. 124902 ◽  
Author(s):  
Daniele Cangialosi ◽  
Angel Alegría ◽  
Juan Colmenero
Keyword(s):  
Temperature Dependence ◽  
Glass Forming

Measurement and Calculation of Residual Stress in Axi-Symmetric Glass Sample Using Structural Relaxation Theory

2008 ◽  
Vol 39-40 ◽  
pp. 529-534
Author(s):  
Norbert Krečmer ◽  
Marek Liška ◽  
Josef Chocholoušek ◽  
Peter Vrábel
Keyword(s):  
Temperature Dependence ◽  
Structural Relaxation ◽  
Coefficient Of Thermal Expansion ◽  
High Stress ◽  
Polarized Light ◽  
Temperature History ◽  
Fictive Temperature ◽  
Stress Calculation ◽  
Applied Model ◽  
Glass Forming

Consistent model including structural relaxation is necessary for correct glass stress calculation in numerical computations of glass forming processes. Calculation of glass relaxation phenomena is often done by combining independent empirical formula on stress relaxation (for a simple temperature regime) and independent model of time-temperature dependence on Tool fictive temperature, Tf. Another approach was developed and verified here. Tool-Narayanaswamy and Moynihan/Mazurin relaxation model was adopted. Relaxation was obtained not from empirical model, but from calculated time-temperature dependence of Tool fictive temperature (Tf), dynamic viscosity, heat capacity and coefficient of thermal expansion. Heat conduction in a glass probe of known temperature history, structural relaxation and stress calculation were used in one computation scheme using Matlab. The stress of glass probe was measured using polarized light (Senarmont method). Rather high stress computation accuracy was obtained in comparison to stress experimental results. The applied model approach is being to be extended for application in commercial finite element codes for modeling of glass forming processes.

scholarly journals Temperature Dependence of Viscosity and Density of cis-1,4/trans-1,3-Dimethylcyclohexane and Several other Commonly Used Organic Solvents

2003 ◽  
Vol 217 (6) ◽  
pp. 707-722 ◽  
Author(s):  
A. A. Ruth ◽  
H. Lesche ◽  
B. Nickel
Keyword(s):  
Low Temperature ◽  
Temperature Dependence ◽  
Organic Solvents ◽  
Temperature Regime ◽  
Dynamic Viscosity ◽  
Temperature Range ◽  
Viscosity Measurements ◽  
Glass Forming ◽  
Temperature Ranges

AbstractThe dynamic viscosity (η) of the glass-forming 50:50 mixture of cis-1,4/trans-1,3-dimethylcyclohexane (ct-DMCH) was measured from 293 K down to ≈ 126 K where η ~ 1.2 × 106 mPas. The viscosity measurements of several other commonly used solvents cover the range from 293 K down to ≈ 148 K (η ~ 1.4 × 104 mPas) for 1-propanol (1-Prop), to ≈118 K (η ~ 2.5 × 102 mPas) for 2-methylpentane (2-MP), to ≈ 167 K (η ~ 10.0 mPas) for isooctane (Isooct), to ≈ 183 K (η ~ 2.8 mPas) for cyclopentane (CP) and down to ≈ 98 K (η ~ 4.6 × 102 mPas) for the 30:70 mixture of cyclopentane/isopentane (CP/IP). The density (ρ) of all solvents was measured correspondingly over appropriate temperature ranges. For the solvents studied here, the temperature dependence of the viscosity can be represented by a single Arrhenius term down to ~180 K. Over a wider temperature range down to ~118K the sum of two Arrhenius terms is required, and in the low temperature regime a Vogel–Tammann–Fulcher expression is necessary to adequately describe the temperature dependence of the dynamic viscosity.

Temperature Dependence of Relaxation Time in Adam-Gibbs Model of Glass-Forming Liquids: Fluctuation Effects

2008 ◽  
Author(s):  
Udayan Mohanty ◽  
Albert Co ◽  
Gary L. Leal ◽  
Ralph H. Colby ◽  
A. Jeffrey Giacomin
Keyword(s):  
Relaxation Time ◽  
Temperature Dependence ◽  
Glass Forming ◽  
Gibbs Model ◽  
Fluctuation Effects
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