Regensburg 2016 – wissenschaftliches Programm
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CPP: Fachverband Chemische Physik und Polymerphysik
CPP 27: Poster: Soft Matter Dynamics / Glasses
CPP 27.4: Poster
Dienstag, 8. März 2016, 18:15–21:00, Poster B2
Time needed to form stable glasses is comparable to β-relaxation time — •Yeong Zen Chua, Mathias Ahrenberg, and Christoph Schick — Institute of Physics, University of Rostock, Rostock 18051 Germany
Glasses produced by physical vapor deposition (PVD) exhibit different properties, depending on the deposition conditions. Consistent with previous works, glasses of ethylcyclohexane (ECH) vapor-deposited at temperature of about 0.85 of glass transition temperature, Tg observed to be the most stable glasses with low enthalpy, low heat capacity, high kinetic stability and high density. Isothermal transformation of the as-deposited glasses into the supercooled state is investigated for the deposition rate dependency, covering four orders of magnitude, at different substrate temperatures. The kinetic stability of the glasses (transformation time at 103 K) shows strong deposition rate dependency for lower substrate temperatures. The data provide an estimate for the substrate temperature dependent free surface residence time needed for the molecules in the assumed mobile surface layer to promote stable glass formation. Stable glasses are formed if this time is of the order of the β-relaxation time, many orders of magnitude faster than the α-relaxation at the substrate temperature. Stable glasses are observed even for substrate temperatures below the Vogel and the Kauzmann temperatures, indicating a full decoupling of the process of stable glass formation from the α-relaxation.