Regensburg 2013 – wissenschaftliches Programm
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CPP: Fachverband Chemische Physik und Polymerphysik
CPP 14: Crystallization, Nucleation and Self Assembly I
CPP 14.4: Vortrag
Dienstag, 12. März 2013, 10:15–10:30, H39
Effect of the Crystalline αc-Process on the Morphology of Semicrystalline Polymers: a Comparative SAXS- Study on Poly-є-Caprolactone and Polyethyleneoxide — Anne Seidlitz, Thomas Thurn-Albrecht, •Ruth Bärenwald, and Kay Saalwächter — MLU Halle-Wittenberg, 06120 Halle (Saale)
Semi-crystalline polymers can be classified into two different types, depending on the presence (αc-mobile) or absence (crystal-fixed) of the αc-relaxation, which provides mobility to the chains in the crystals. Starting from a hypothesis of Boyd, that all polymers with a high crystallinity are αc-mobile while all polymers with a low crystallinity are crystal-fixed, we investigated the morphology of polyethyleneoxide as a polymer with mobile crystalline chains and poly-є-caprolactone as a polymer with fixed chains. We performed small-angle X-ray scattering experiments and developed a simulation based on the paracrystalline model to derive quantitative morphological information from the SAXS data. Clear differences between the structure of PEO and PCL were observed. For PCL the crystalline thickness dc is well defined, while the amorphous thickness da displays a broad distribution. PEO shows a small, well defined da and a broad thickness distribution of the crystalline lamellae.This confirms a different mode of structure formation. The crystalline lamellae in PEO, where thickening begins already at the growth front, can reorganize during crystallization until a minimal da, possibly reflecting a locally equilibrated entanglement structure, is established. For PCL no thickening of the initially formed lamellae is possible and the amorphous parts are randomly filled.