The Temperature and Pressure Dependence of the Free Volume in Fluoroelastomers from PALS and PVT Experiments

G. Dlubeka, A. Sen Guptab,c, J. Wawryszczukd, D. Kilburn e, J. Pionteckf, R. Krause-Rehberg b, T. Goworekd, M.A. Alame, H. Kasparg, K.H. Lochhaasg aITA Inst. Innovative Technologies, Wiesenring 4, 06120 Lieskau (Halle/S.), Germany bDepartment of Physics, Martin-Luther-University, 06099 Halle/S., Germany cDep. of Physics, Visva-Bharati, Central University, Santiniketan, West Bengal-731235, India dInstitute of Physics, Maria Curie-Skłodowska University, 20-031 Lublin, Poland eH.H. Wills Physics Laboratories, Univ. of Bristol, Tyndall Avenue, Bristol, BS8 1TL, UK fLeibniz-Institute of Polymer Research, Hohe Strasse 6, 01069 Dresden, Germany gDyneon GmbH& Co. KG, Werk Gendorf, 84504 Burgkirchen, Germany

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Received: 20 09 2004;

Positron lifetime and pressure-volume-temperature experiments were performed as function of T (100-485 K) and P (10-5 Pa-500 MPa) on a fluoroelastomer. From positron annihilation lifetime spectroscopy, analyzed with LT9.0 assuming a dispersion in the e+ (τ2) and o-Ps (τ3) lifetime, the mean,〈vh〉, and the width (standard deviation),σh, of the hole size distribution were calculated. The pressure-volume-temperature data were analyzed using the Simha-Somcynsky hole-lattice theory to estimate the specific hole free volume Vf. From a comparison of Vf with〈vh〉 the specific hole number, N'h, is estimated. The data from thermal expansion and pressure experiments show complete agreement when taking into account the compressibility of the occupied volume.

DOI: 10.12693/APhysPolA.107.685 PACS numbers:61.41.+e, 78.70.-g