Regensburg 2007 – scientific programme

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CPP: Fachverband Chemische Physik und Polymerphysik

CPP 2: Polymer Physics I

CPP 2.8: Talk

Monday, March 26, 2007, 12:00–12:15, H40

Skotometrical Investigation of Volume Changes during Rapid Deformation of Elastomers — •Michael Kerscher, Gerald Johannes Schneider, and Dietmar Göritz — Institut für Physik, Universität Regensburg, 93040 Regensburg

Polymer composites consisting of a filler and an elastomer are indispensable for daily life. Thus, an enormous effort is done to understand their properties. When trying to derive constitutive equations for elastomers, the constance of volume on deformation is one of the major assumptions to be made. Already several decades ago, however, experiments showed a volume expansion, albeit very small. Therefore, a constant volume has still been assumed even though these experiments were only performed at small strain rates or with slow measuring processes not considering a possible effect at short time intervalls.

In our contribution, we show the influence of deformation velocity on volume expansion at high deformation rates. For this purpose, in our experiments we use an optical dilatometer based on the principle of a scotometer (from greek “σκoταδι”: darkness) which allows measurement of volume changes in the range of a few milliseconds.

Our experiments point to a by far higher volume change than expected from slow deformation which then relaxate in the range of several milliseconds. These new results have to be taken into consideration when trying to fully understand the laws behind the deformation of elastomers.