Dresden 2006 – scientific programme

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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.