In search of invariants for viscous liquids in the density scaling regim : investigations of dynamic and thermodynamic moduli
PBN-AR
Instytucja
Wydział Matematyki, Fizyki i Chemii (Uniwersytet Śląski w Katowicach)
Informacje podstawowe
Główny język publikacji
angielski
Czasopismo
PHYSICAL CHEMISTRY CHEMICAL PHYSICS (40pkt w roku publikacji)
ISSN
1463-9076
EISSN
Wydawca
ROYAL SOC CHEMISTRY
DOI
URL
Rok publikacji
2017
Numer zeszytu
Strony od-do
18348-18355
Numer tomu
28
Identyfikator DOI
Liczba arkuszy
0,40
Streszczenia
Język
angielski
Treść
In this paper, we report the nontrivial results of our investigations of dynamic and thermodynamic moduli in search of invariants for viscous liquids in the density scaling regime by using selected supercooled van der Waals liquids as representative materials. Previously, the dynamic modulus Mp–T (defined in the pressure–temperature representation by the ratio of isobaric activation energy and activation volume) as well as the ratio BT/Mp–T (where BT is the thermodynamic modulus defined as the inverse isothermal compressibility) have been suggested as some kinds of material constants. We have established that they are not valid in the explored wide range of temperatures T over a dozen decades of structural relaxation times τ. The temperature dependences of Mp–T and BT/Mp–T have been elucidated by comparison with the well-known measure of the relative contribution of temperature and density fluctuations to molecular dynamics near the glass transition, i.e., the ratio of isochoric and isobaric activation energies. Then, we have implemented an idea to transform the definition of the dynamic modulus Mp–T from the p–T representation to the V–T one. This idea relied on the disentanglement of combined temperature and density fluctuations involved in isobaric parameters and has resulted in finding an invariant for viscous liquids in the density scaling regime, which is the ratio of thermodynamic and dynamic moduli, BT/MV–T. In this way, we have constituted a characteristic of thermodynamics and molecular dynamics, which remains unchanged in the supercooled liquid state for a given material, the molecular dynamics of which obeys the power density scaling law.
Cechy publikacji
original-article
Inne
System-identifier
3342800136840