A Simplified Method for the Estimation of Hole Free Volume Fraction from the Specific Volume
G. Dlubek a and J. Pionteck b
a ITA Institut fűr Innovative Technologien, Köthen, Aussenstelle Halle, Wiesenring 4, D-06120 Lieskau (bei Halle/S.), Germany
b Leibniz-Institut fűr Polymerforschung Dresden e.V., Hohe Strasse 6, D-01069 Dresden, Germany
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Received: 3 09 2007;
A brief introduction in the equation of state of the Simha-Somcynsky hole theory is presented. This theory allows to calculate the volume fraction h of free volume holes from pressure-volume-temperature experiments. These holes are detected by ortho-positronium and from the value of h and the mean ortho-positronium hole size the hole density may be calculated. We discuss a simplified method to estimate h which makes use of the relation V* = 1.52VW between the scaling volume V* of the Simha-Somcynsky hole theory equation of state and the van der Waals volume VW. Moreover, we present a new simplified method for the estimation of h which starts with the Schottky (Arrhenius) equation for the concentration of thermal vacancies and makes use of a linear relation between the scaling temperature T* and the hole formation enthalpy Hh, Hh(kJ/mol)=6.54×10-4 T*(K).
DOI: 10.12693/APhysPolA.113.1331
PACS numbers: 61.41.+e, 78.70.-g