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CPP: Chemische Physik und Polymerphysik
CPP 3: Polymer Materials
CPP 3.1: Talk
Monday, March 27, 2006, 10:00–10:15, ZEU 114
Generalized Cauchy Relation For Reactive Polymers: Epoxies and Polyurethanes, a comparison — •Christelle Vergnat1, Martine Philipp2, Ravi Bactavatchalou1, Jörg Baller2, Wulf Possart1, Ulrich Müller1, Patrick Alnot3, Roland Sanctuary2, and Jan K. Krüger1 — 1Laboratoire Europpéen de Recherche Universitaire Saarland-Lorraine-Luxembourg Universität des Saarlandes D-66123 Saarbrücken — 2Université de Luxembourg, 162a,Avenue de la Faiencerie L-1511 Luxembourg — 3Université de Nancy, Bd des Aiguillettes F-54506 Vandoeuvre
The generalized Cauchy Relation c11=B c44+A for isotropic materials is a linear transformation which strongly reduces the independence of the two remaining elastic constants c11 and c44 of the isotropic state. The pre-factor B usually reflects the global symmetry and has a value of three. The parameter A seems to be indicative to the difference between global and local symmetry of the material. At sufficient high probe frequencies the generalized relation even holds for the liquid state and doesn*t change at the transition to the glassy state. As a matter of fact the generalized Cauchy relation is even maintained during the curing process of reactive polymers. Within this contribution we present Cauchy Relations for epoxies and polyurethanes. The results will be discussed in the context of local symmetry and local heterogeneity.