Berlin 2001 – scientific programme

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CPP: Chemische Physik und Polymerphysik

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

CPP 16.19: Poster

Monday, April 2, 2001, 12:30–15:00, AT1

Influence of Vitrification on Dynamic Glass-Transition - Description with an Extended Tool-Narayanaswamy-Moynihan Model — •Stefan Weyer, Mikhail Merzliakov, and Christoph Schick — Universitaet Rostock, Universitaetsplatz 3, 18051 Rostock

Two aspects of glass-transition can be considered: thermal glass-transition (vitrification) and dynamic glass-transition (relaxation process). The thermal glass-transition describes a transition from the liquid state (equilibrium) to the solid state (glass, non-equilibrium) without structural changes. This is connected with a relaxation process, which can be observed in thermal equilibrium (dynamic glass-transition). We investigated how partial vitrification influences the relaxation process in heat capacity and whether the results can be described by an extended Tool-Narayanaswamy-Moynihan (TNM) model.

With temperature-modulated DSC (TMDSC) both aspects of glass-transition can be observed simultaneously, thermal glass-transition due to underlying cooling rate and dynamic glass-transition in the response to temperature modulation (frequency dependent). We have fixed the dynamic glass-transition temperature using a fixed frequency of 16,67 mHz. Vitrification can be shifted by varying underlying cooling rate in order to study their influence on the relaxation process in heat capacity. Experimental results will be compared with model-calculations based on an extended TNM algorithm.