Berlin 2001 – wissenschaftliches Programm

Bereiche | Tage | Auswahl | Suche | Downloads | Hilfe

CPP: Chemische Physik und Polymerphysik

CPP 16: Poster: Dynamics of Molecular Systems, Polymer Dynamics, Glass Transition, Crystallization, Electronic Properties of Polymers

CPP 16.6: Poster

Montag, 2. April 2001, 12:30–15:00, AT1

The Kinetics of Crystallization of 2-Methylpentane — •Wolfgang Manglkammer, Andrä le Coutre, Thomas Britz, and Jan K. Krüger — Universität des Saarlandes, FR 7.2 Experimentalphysik, Geb. 38, 2. OG, Postfach151150, D-66041 Saarbrücken

Super-cooled molecular liquids may be subject to a severe competition between crystallization and freezing into the glassy state, and therefore show a strange transformation behaviour into the different solid states. We investigated the kinetics of solidification and phase transformations of the non-ideal glass former 2-methylpentane by several static and dynamic methods, for example Temperature Modulated DSC and Brillouin spectroscopy.

We did not succeed in crystallizing 2-methylpentane during cooling, which always resulted in the glass transition of the material at 78 K. On reheating suitable temperature programs allowed the inhibited nucleation and the subsequent crystal growth of the metastable phase, which melts several degree below the known melting temperature of the equilibrium phase at 119 K. The stable crytalline phase nucleates inside of the metastable phase and grows significantly only if the metastable matrix is completely molten. The energetically nearly equivalent conformations of the rather small molecule 2-methylpentane may play a major role for the frustration of the crystallization.