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CPP: Chemische Physik und Polymerphysik

CPP 12: Crystallization in Polymers

CPP 12.5: Vortrag

Donnerstag, 5. April 2001, 17:05–17:25, 111

Crystallinity dependence of the electronic structure of polyethylene — •A. Schöll¹, St. Urquhart², H. Ade², R. Fink¹, and E. Umbach¹ — ¹Experimentelle Physik II, Universität Würzburg, Am Hubland, 97074 Würzburg — ²NCSU Raleigh, Dept.of Physics, Box 8202, Raleigh, NC27695, USA

The mechanical and electronic properties of polymers strongly depend on the intermolecular interaction. Using high-resolution near-edge X-ray absorption fine structure (NEXAFS) (recorded by scanning transmission x-ray microspectroscopy at NSLS Brookhaven) the influence of different branch lengths and branching ratios has been investigated for polyethylene in detail. Systematic changes in the C 1s NEXAFS spectra and the results of annealing experiments provide unambiguous evidence for different fractions of crystalline and amorphous phases. Ab-initio calculations reflect the relatively strong influence of matrix effects on the electronic structure and reproduce the behaviour of the distinct C-H σ/Rydberg resonances observed between 287 and 289 eV. The different nearest neighbour distributions in the crystalline and amorphous phases and are therefore consistent with our experimental data (funded by BMBF, Fkz. 05 SF8 WWA7).