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CPP: Chemische Physik und Polymerphysik

CPP 29: POSTER: Polymer physics

CPP 29.52: Poster

Dienstag, 8. März 2005, 16:30–18:30, Poster TU D

Using NMR in studies of the kinetics of polymer crystallisation — •Christopher Hertlein¹, Kay Saalwächter², and Gert Strobl¹ — ¹Fakultät für Mathematik und Physik, Hermann-Herder-Str. 3, 79104 Freiburg, Germany — ²Institut für Makromolekulare Chemie, Universität Freiburg, Stefan-Meier Str. 31, 79104 Freiburg, Germany

In our work we investigated the crystallization kinetics of several semicrystalline polymers using proton-NMR relaxation experiments. As crystallization of a polymer goes along with a solidification of the material and therefore with a substantial increase in dipolar coupling among the protons, NMR is a suitable method due to its sensitivity to dipolar couplings. The materials under investigation were poly(ethylene-co-octene), poly-(ε-caprolactone) and syndiotactic polypropylene.
Different parts of registered NMR decay curves could be related to a melt, a crystalline phase and non-crystalline regions with a reduced mobility. The decay curve measured at the very beginning of the crystallization process represents the melt. Scaling the melt-curve with a time-dependent calculated factor representing the remaining melt fraction, and substracting it from each curve, we obtained for all times the decay curves of the non melt-like parts of the sample. Usually the crystal contribution to the curves could be identified and the development of the crystallinity with time determined. A comparison with results obtained by small- and wide-angle X-ray scattering and dilatometry indicate a formation of crystals out of regions with a reduced mobility.