Regensburg 2004 – wissenschaftliches Programm
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CPP: Chemische Physik und Polymerphysik
CPP 7: Physics of Polymers I
CPP 7.5: Vortrag
Montag, 8. März 2004, 15:00–15:15, H 37
On the Nature of the Chemically Induced Glass Transition — •Thomas Britz1, Jan Kristian Krüger1, Ulrich Müller1, Ravindrakumar Bactavatchalou1, and Roland Sanctuary2 — 1Universität des Saarlandes, Fachrichtung 7.2 Experimentalphysik, Geb. 38, Postfach 151150, D-66041 Saarbrücken — 2Centre Universitaire de Luxembourg, Département des Sciences, Laboratoire 1.19, 162a Avenue de la Faiencerie, L-1511 Luxembourg
We investigated the curing process in epoxy resins by means of Brillouin and infrared scattering as well as refractive index measurements. Longitudinal and transverse acoustic mode Grüneisen parameters (MGPs) diverge during the freezing process, which indicates, that the chemical glass transition is accompagnied by an anomaly of acoustic anharmonicitiy. The MGPs jump from a higher level prior to a lower level after the freezing process, which suggests, that the chemical glass transition has phase transition character. During curing, the elastic moduli c11 and c44 of all epoxy resins obey a generalized Cauchy-relation. This relation is not affected by the glass transition. Epoxy resins filled with nanoparticles of SiO2 show the same behavior as well as polyurethane systems and a row of thermal glass formers.