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CPP: Fachverband Chemische Physik und Polymerphysik
CPP 8: POSTER: Polymer Physics
CPP 8.3: Poster
Monday, March 26, 2007, 16:00–18:00, Poster B
Advanced ultrafast nanocalorimetry: superheating in linear polymers — •Alexander Minakov1, Andreas Wurm2, and Christoph Schick2 — 1A.M. Prokhorov General Physics Institute, Vavilov 38, 119991 Moscow, Russia — 2University of Rostock, Institute of Physics, Universitätsplatz 3, 18051 Rostock, Germany
To study phase transition kinetics on submillisecond time scale a set of new membrane gauges for ultrafast scanning nanocalorimetry were constructed. Controlled ultrafast cooling, as well as heating, up to 1 million K/s was attained. The dynamic model describing the temperature distribution at ultrafast temperature change in the membrane-gas system was developed. The characteristic rate corresponding to the quasi-static limit of the temperature change in the membrane-gas system was determined. The rate equals 0.1 million K/s for different gauges in helium gas. The method was applied for the measurements of the superheating phenomenon in a set of linear polymers iPS, PBT, PET, iPP. A power law relation between the superheating and the heating rate was observed in the range 0.01 - 10000 K/s of heating rates. A superheating limit about 10% of the melting temperature was fined out at the rates above 0.01 - 0.1 millions K/s. This limit depends on the sample crystallization temperature. The observed superheating limit, as well as the power law, can be accounted for the internal stress induced by the superheating near the crystalline-amorphous interfaces in the semicrystalline polymers.