Connection Between Dynamics and Thermodynamics of Liquids on the Melting Line
Abstract
The dynamics of a large number of liquids and polymers exhibit scaling properties characteristic of a simple repulsive inverse power-law potential, most notably the superpositioning of relaxation data as a function of the variable TV gamma , where T is temperature, V the specific volume, and gamma a material constant. A related scaling law Tm Vm Gamma , with the same exponent Gamma = gamma, links the melting temperature Tm and volume Vm of the model IPL liquid; liquid dynamics is then invariant at the melting point. Motivated by a similar invariance of dynamics experimentally observed at transitions of liquid crystals, we determine dynamic and melting-point scaling exponents and Gamma for a large number of nonassociating liquids. Rigid, spherical molecules containing no polar bonds have Gamma = gramma; consequently, the reduced relaxation time, viscosity, and diffusion coefficient are each constant along the melting line. For other liquids gamma > Gamma always; that is, the dynamics is more sensitive to volume than is the melting point, and for these liquids the dynamics at the melting point slows down with increasing Tm (that is, increasing pressure).
Document Details
- Document Type
- Technical Report
- Publication Date
- Mar 21, 2011
- Accession Number
- ADA553370
Entities
People
- C. Michael Roland
- D. Fragiadakis
Organizations
- United States Naval Research Laboratory