Regensburg 2004 – wissenschaftliches Programm
CPP 13: SYMPOSIUM: Understanding and Controlling Complex Structures: From Synthetic Polymers to Biomaterials I
CPP 13.3: Vortrag
Dienstag, 9. März 2004, 10:30–10:45, H 37
Melting and reorganization of polymer crystals on fast heating (1,000 K/s) — •Christoph Schick1 and Alexander Minakov2 — 1Universitaet Rostock, FB Physik, Universitaetsplatz 3, 18051 Rostock — 2Natural Science Center of General Physics Institute, Vavilov st. 38, 199911 Moscow, Russia
Reorganization of polymer crystals on heating is a well known phenomenon. But kinetics of the process is mainly unknown because it is very fast. Utilizing a thin film vacuum gauge as a calorimeter we are able to extend the scanning rate range of commercial DSC’s (10E-6 K/s to 10 K/s) to rates as high as 10,000 K/s. Because of the fast equilibration time isothermal experiments can be performed after scanning at several thousand K/s. The dead time after such a quench is in the order of 10 ms and the time resolution is in the order of milliseconds. These ultra fast calorimeters allow studying kinetics of crystal reorganization in polymers, which appears on time scales in the order of 10 milliseconds. Compared to crystallization from the isotropic melt at the same temperature reorganization of existing polymer crystals is about two orders of magnitude faster. For PET at highest rates only one single melting peak is seen independent on crystallization temperature. This ’true’ melting corresponds to the lowest endotherm in DSC curves.