### Resumé

Originalsprog | Engelsk |
---|---|

Publikationsdato | 2004 |

Status | Udgivet - 2004 |

Begivenhed | International Workshop on Dynamics in Viscous Liquids - München, Tyskland Varighed: 14 mar. 2004 → 17 mar. 2004 Konferencens nummer: 1 |

### Konference

Konference | International Workshop on Dynamics in Viscous Liquids |
---|---|

Nummer | 1 |

Land | Tyskland |

By | München |

Periode | 14/03/2004 → 17/03/2004 |

### Citer dette

*Testing for one Generalized Linear Single Order Parameter*. Poster session præsenteret på International Workshop on Dynamics in Viscous Liquids, München, Tyskland.

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**Testing for one Generalized Linear Single Order Parameter.** / Ellegaard, Niels Langager; Christensen, Tage Emil; Dyre, Jeppe; Olsen, Niels Boye.

Publikation: Konferencebidrag › Poster › Forskning

TY - CONF

T1 - Testing for one Generalized Linear Single Order Parameter

AU - Ellegaard, Niels Langager

AU - Christensen, Tage Emil

AU - Dyre, Jeppe

AU - Olsen, Niels Boye

PY - 2004

Y1 - 2004

N2 - We examine a linear single order parameter model for thermoviscoelastic relaxation in viscous liquids, allowing for a distribution of relaxation times. In this model the relaxation of volume and entalpy is completely described by the relaxation of one internal order parameter. In contrast to prior work the order parameter may be chosen to have a non-exponential relaxation. The model predictions contradict the general consensus of the properties of viscous liquids in two ways: (i) The model predicts that following a linear isobaric temperature step, the normalized volume and entalpy relaxation functions are identical. This assumption conflicts with some (but not all) reports, utilizing the Tool-Narayanaswamy formalism to extrapolate from non-linear measurements to the linear regime. (ii) The model predicts that the theoretical "linear Prigogine-Defay" ratio is one. This ratio has never been accurately measured, however, as this involves the measurement on a equilibrium liquid of three linear static responses and three linear instantaneous responses. The existing experimental reports of the Prigogine-Defay ratio either fail to measure a truly linear, instantaneous, isobaric and isothermal responses or extrapolate from measurements of a glassy state away from equilibrium. Starting from a master equation description of inherent dynamics, we calculate the complex thermodynamic response functions. We device a way of testing for the generalized single order parameter model by measuring 3 complex response functions at a single frequency.

AB - We examine a linear single order parameter model for thermoviscoelastic relaxation in viscous liquids, allowing for a distribution of relaxation times. In this model the relaxation of volume and entalpy is completely described by the relaxation of one internal order parameter. In contrast to prior work the order parameter may be chosen to have a non-exponential relaxation. The model predictions contradict the general consensus of the properties of viscous liquids in two ways: (i) The model predicts that following a linear isobaric temperature step, the normalized volume and entalpy relaxation functions are identical. This assumption conflicts with some (but not all) reports, utilizing the Tool-Narayanaswamy formalism to extrapolate from non-linear measurements to the linear regime. (ii) The model predicts that the theoretical "linear Prigogine-Defay" ratio is one. This ratio has never been accurately measured, however, as this involves the measurement on a equilibrium liquid of three linear static responses and three linear instantaneous responses. The existing experimental reports of the Prigogine-Defay ratio either fail to measure a truly linear, instantaneous, isobaric and isothermal responses or extrapolate from measurements of a glassy state away from equilibrium. Starting from a master equation description of inherent dynamics, we calculate the complex thermodynamic response functions. We device a way of testing for the generalized single order parameter model by measuring 3 complex response functions at a single frequency.

M3 - Poster

ER -