Berlin 2008 – wissenschaftliches Programm
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CPP: Fachverband Chemische Physik und Polymerphysik
CPP 34: POSTERS Polymerphysics
CPP 34.1: Poster
Donnerstag, 28. Februar 2008, 17:00–19:30, Poster A
About the Generalized Cauchy Relation in Non-Equilibrium Amorphous Materials — •Martine Philipp1, Christelle Vergnat1, Ulrich Müller1, Ravi Bactavatchalou1, Wulff Possart2, Roland Sanctuary1, Jörg Baller1, Bartosz Zielinski1, Patrick Alnot3, and Jan Krüger1 — 1LPM, Université du Luxembourg, L-1115 Luxembourg — 2Universität des Saarlandes, Saarbrücken, Germany — 3Université Nancy, France
From solid state physics it is known that Cauchy relations (CR) increase the symmetry of the elastic tensor compared to the actual point symmetry. These CR hold true only under severe conditions concerning local symmetry and harmonicity of the elastic interaction potential. Since amorphous materials show no translational invariance the existence of CRs is not expected for these materials. Nevertheless, the authors have found for amorphous solids and high frequency clamped liquids a generalized CR (gCR) under the form of a linear transformation c11=3c44+A, with A being a constant. Once A is known, one of the two elastic constants can be predicted by knowing the other. This surprising result means that for amorphous materials the independency of the two elastic constants is strongly reduced. In the current presentation we discuss to which extent thermodynamic non-equilibrium violates the gCR. For that purpose the interdependency of c11 and c44 of reactive polymers is studied in the course of the curing process by Brillouin spectroscopy. Special attention is paid to accompanying transition phenomena like gelation and chemically induced freezing. An attempt is made to interpret the parameter A.