Berlin 2008 – wissenschaftliches Programm

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CPP: Fachverband Chemische Physik und Polymerphysik

CPP 34: POSTERS Polymerphysics

CPP 34.25: Poster

Donnerstag, 28. Februar 2008, 17:00–19:30, Poster A

Hyperquenching in linear polyethylene and ultrafast calorimetry at heating and cooling rates up to 2 millions K/s — •Alexander Minakov^1,2 and Christoph Schick¹ — ¹University of Rostock, Institute of Physics, Universitätsplatz 3, 18051 Rostock, Germany — ²A.M. Prokhorov General Physics Institute, Vavilov 38, 119991 Moscow, Russia

Ultrafast nanocalorimetry was applied for hyperquenching in ultra high molecular weight linear polyethylene (UHMWPE). We determine the quenching rate required to obtain amorphous polyethylene from the melt. UHMWPE can be strongly supercooled at high cooling rates. The peak in heat capacity cp(T) corresponding to crystallization shifts to lower temperatures with increasing cooling rate in the range 10^3 - 10^5 K/s. This shift attains saturation at the rate 10^5 K/s. At subsequent increasing cooling rate the peak in cp(T) decreases. Crystallization can not be accomplished for 10 μs. Totally amorphous PE sample at cooling and subsequent heating rate ca. 2*10^6 K/s was obtained for samples of 0.1 ng and 0.06 ng (the samples thickness was ca. 0.1 μ). Considerable superheating of the melting in UHMWPE was observed. We have performed superheating measurements for 2.5 ng and 0.06 ng samples melt-crystallized for 1 min at 96°C and 106°C in the range 2*10^3 - 2*10^6 K/s of the heating rate. The rate dependence of superheating increment is described by the power law with exponent 0.212.