Scaling of the Local Dynamics and the Intermolecular Potential

Abstract

The experimental fact that relaxation times, tau, of supercooled liquids and polymers are uniquely defined by the quantity TV^g, where T is temperature, V specific volume, and g a material constant, leads to a number of interpretations and predictions concerning the dynamics of vitrification. Herein we examine means to determine the scaling exponent g apart from the usual superpositioning of relaxation data. If the intermolecular potential can be approximated by an inverse power law, as implied by the TV^g scaling, various equations are derived relating g to the Gruneisen parameter and to a common expression for the pressure derivative of the glass temperature. In addition, without assumptions, g can be obtained directly from pressure-volume-temperature data. These methods for determining g from molecular or thermodynamic properties are useful because they enable the P- and V-dependences of tau to be obtained, and thereby various analyses of the dynamics to be explored, without the need to carry out relaxation measurements beyond ambient pressure.

13 pages, 4 figures proceedings of 5th IDMRCS, Lille, France, July 2005

References in corpus (12)

• Thermodynamical Scaling of the Glass Transition Dynamics
• Neutron Scattering Studies of the Model Glass Former Ortho-terphenyl
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• Scaling the alpha-relaxation time of supercooled fragile organic liquids
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• Disentangling density and temperature effects in the viscous slowing down of glassforming liquids
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• Temperature and Density Effects on the Local Segmental and Global Chain Dynamics of Poly(oxybutylene)
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• Pressure-energy correlations in liquids. III. Statistical mechanics and thermodynamics of liquids with hidden scale invariance
• Scaling of Volumetric Data in Model Systems Based on the Lennard-Jones Potential
• Entropy Basis for the Thermodynamic Scaling of the Dynamics of OTP
• Connection between dynamics and thermodynamics of liquids on the melting line
• Density scaling of the diffusion coefficient at various pressures in viscous liquids
• Activation Volume in the Density Scaling Regime: Equation of State and Its Test by Using Experimental and Simulation Data
• Correlation of the scaling exponent of the diffusivity-density function in viscous liquids with their elastic properties
• A plausible interpretation of the density scaling of the diffusivity in viscous liquids