Related Experiment Video
Updated: Jul 7, 2026
09:32
Cooling Rate Dependent Ellipsometry Measurements to Determine the Dynamics of Thin Glassy Films
Published on: January 26, 2016
Activated dynamics and effective temperature in a steady state sheared glass
Thomas K Haxton1, Andrea J Liu
1Department of Physics and Astronomy, University of Pennsylvania, Philadelphia, PA, 19104, USA.
Physical Review Letters
|February 1, 2008
Summary
Simulations reveal that effective temperature controls the behavior of sheared glasses, particularly in the shear-dominated regime. This finding applies to both high and low temperatures relative to the glass transition temperature.
Area of Science:
- Condensed Matter Physics
- Materials Science
- Computational Chemistry
Background:
- Glassy materials exhibit complex rheological behavior under shear.
- Understanding the relationship between temperature, shear rate, and material response is crucial for predicting glass properties.
Purpose of the Study:
- To investigate the rheological properties of a sheared model glass.
- To determine the influence of bath temperature (T) and shear strain rate (gamma) on shear stress (sigma), inherent structure energy (E{IS}), and effective temperature (T{eff}).
Main Methods:
- Nonequilibrium molecular dynamics simulations were employed.
- Measurements of shear stress, inherent structure energy, and effective temperature were performed.
Main Results:
- Above the glass transition temperature (T0), the system approaches Newtonian behavior with T{eff} approaching T as shear rate decreases.
- Below T0, shear stress approaches a yield stress, and T{eff} stabilizes near T0.
- In the shear-dominated regime, both shear stress and inherent structure energy collapse onto a single curve as a function of effective temperature.
Conclusions:
- Effective temperature (T{eff}) is a key parameter governing the behavior of sheared glasses in the shear-dominated regime.
- The findings suggest a universal control mechanism for glass rheology under specific conditions.
Related Concept Videos
01:21Joule-Thomson Effect
The Joule-Thomson effect, also known as the Joule-Kelvin effect, describes the temperature change of a fluid when it is forced through a valve or porous plug while keeping it in a thermally insulated environment. This experiment is called a throttling process. This is an important effect widely used in refrigeration and the liquefaction of gases.
This experiment forces high-pressure gas through a throttle valve or a porous plug to a lower-pressure region. The gas expands as it passes through to...
This experiment forces high-pressure gas through a throttle valve or a porous plug to a lower-pressure region. The gas expands as it passes through to...
01:17Steady, Laminar Flow Between Parallel Plates
Understanding steady, laminar flow between parallel plates is essential for analyzing and designing flow in narrow rectangular channels, commonly found in various water conveyance and drainage systems. The Navier-Stokes equations govern fluid motion and are generally challenging to solve due to their nonlinearity. However, simplifications are possible in certain cases, like the steady laminar flow between parallel plates. For this scenario, we assume steady, incompressible, laminar flow.
01:20Mechanisms of Heat Transfer II
In convection, thermal energy is carried by the large-scale flow of matter. Ocean currents and large-scale atmospheric circulation, which result from the buoyancy of warm air and water, transfer hot air from the tropics toward the poles and cold air from the poles toward the tropics. The Earth’s rotation interacts with those flows, causing the observed eastward flow of air in the temperate zones. Convection dominates heat transfer by air, and the amount of available space for the airflow...
02:44Heating and Cooling Curves
When a substance—isolated from its environment—is subjected to heat changes, corresponding changes in temperature and phase of the substance is observed; this is graphically represented by heating and cooling curves.
For instance, the addition of heat raises the temperature of a solid; the amount of heat absorbed depends on the heat capacity of the solid (q = mcsolidΔT). According to thermochemistry, the relation between the amount of heat absorbed or released by a substance, q, and its...
For instance, the addition of heat raises the temperature of a solid; the amount of heat absorbed depends on the heat capacity of the solid (q = mcsolidΔT). According to thermochemistry, the relation between the amount of heat absorbed or released by a substance, q, and its...
02:19Le Chatelier's Principle: Changing Temperature
Consistent with the law of mass action, an equilibrium stressed by a change in concentration will shift to re-establish equilibrium without any change in the value of the equilibrium constant, K. When an equilibrium shifts in response to a temperature change, however, it is re-established with a different relative composition that exhibits a different value for the equilibrium constant.
To understand this phenomenon, consider the elementary reaction:
To understand this phenomenon, consider the elementary reaction:
01:14Mechanisms of Heat Transfer I
Just as interesting as the effects of heat transfer on a system are the methods by which the heat transfer occur. Whenever there is a temperature difference, heat transfer occurs. It may occur rapidly, such as through a cooking pan, or slowly, such as through the walls of a picnic ice box. So many processes involve heat transfer that it is hard to imagine a situation where no heat transfer occurs. Yet, every heat transfer takes place by only three methods: conduction, convection, and radiation.