Lecture

Time-Temperature Equivalence in Rheology

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In course

MSE-206: Rheology and fluid mechanics

Ce cours est une introduction à la rhéologie des solides viscoélastiques linéaires, aux phénomènes d'écoulements des fluides, et aux méthodes utilisées en rhéologie. Les fluides Newtoniens ou non, la turbulence, les fluides réactifs et les suspensions sont ...

Description

This lecture by the instructor covers the concept of time-temperature equivalence in rheology, focusing on the relationship between temperature and time in material behavior, as well as the Arrhenius and WLF models for polymer properties. The presentation delves into the shift factors, activation energy, and the free volume concept, providing insights into the viscoelastic properties of polymers at different temperatures.

Instructor

Yves Leterrier

Yves Leterrier joined EPFL in 1993 and is a faculty member of the Materials Institute. He is a senior scientist and lecturer in the Laboratory for Processing of Advanced Composites (LPAC, previously Laboratory of Composite and Polymer Technology, LTC). Activities 2000-2005: Foundation and Chair of the Korea-Switzerland joint symposia on materials and micro-technologies2004-2008: Board member of FLEXIDIS (the European flexible display consortium) 2004-2009: Group leader on lightweight materials for Solar ImpulseSince 2008: Board member of the French Adhesion SocietySince 2000: President of the EPFL Materials Science Library commissionSince 2012: Editorial board member, Applied Surface ScienceSince 2014: Associate Editor, Frontiers in MaterialsSince 2021: Coordinator of the EPFL Minor on 'Engineering for Sustainability' Background 1987: MS in materials science and solid state physics (INPL, France) 1991: PhD in materials science (Ecole des Mines, INPL, France) 1992: Research Associate, National Institute of Standards and Technology (NIST, USA)

Official source

Related concepts (31)

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Gibbs free energy

In thermodynamics, the Gibbs free energy (or Gibbs energy as the recommended name; symbol ) is a thermodynamic potential that can be used to calculate the maximum amount of work, other than pressure-volume work, that may be performed by a thermodynamically closed system at constant temperature and pressure. It also provides a necessary condition for processes such as chemical reactions that may occur under these conditions. The Gibbs free energy is expressed as where p is pressure, T is the temperature, U is the internal energy, V is volume, H is the enthalpy, and S is the entropy.

Thermodynamic free energy

In thermodynamics, the thermodynamic free energy is one of the state functions of a thermodynamic system (the others being internal energy, enthalpy, entropy, etc.). The change in the free energy is the maximum amount of work that the system can perform in a process at constant temperature, and its sign indicates whether the process is thermodynamically favorable or forbidden. Since free energy usually contains potential energy, it is not absolute but depends on the choice of a zero point.

Helmholtz free energy

In thermodynamics, the Helmholtz free energy (or Helmholtz energy) is a thermodynamic potential that measures the useful work obtainable from a closed thermodynamic system at a constant temperature (isothermal). The change in the Helmholtz energy during a process is equal to the maximum amount of work that the system can perform in a thermodynamic process in which temperature is held constant. At constant temperature, the Helmholtz free energy is minimized at equilibrium.

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