Regensburg 2002 – wissenschaftliches Programm

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CPP: Chemische Physik und Polymerphysik

CPP 4: Poster: Dynamik in polymeren Systemen

CPP 4.3: Poster

Montag, 11. März 2002, 13:30–15:00, B

How independent are the elastic constants of isotropic macromolecular materials?- Empirical investigation of a generalized Cauchy Relation — •Andrä le Coutre, Jörg Baller, Thomas Britz, and Jan K. Krüger — FR 7.2 Experimentalphysik, Universität des Saarlandes, 66123 Saarbrücken

Thermal freezing of polymer materials as well as vulcanization of macromolecules lead to the appearance of static shear stiffness. At very high frequencies a (dynamically clamped) shear modulus c44 can be measured by Brillouin spectroscopy already well above the thermal glass transition temperature. Astonishingly the dynamically clamped moduli c11 and c44 follow a linear relation c11=A+B*c44 which is valid for the glassy (T<Tg) and the liquid (T>Tg) state with the same parameters A and B. Furthermore even the strongly non-linear behavior of c11 and c44 during polymerization of epoxy resins satisfies this relation. The linear relationship between both moduli appears as a generalization of the well known Cauchy relation which usually only fits under special restrictions. The linear relation has been confirmed for rather different materials.