Berlin 2012 – wissenschaftliches Programm

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CPP: Fachverband Chemische Physik und Polymerphysik

CPP 17: Poster: Crystallisation, Nucleation and Self assembly

CPP 17.3: Poster

Dienstag, 27. März 2012, 18:15–20:15, Poster A

Effect of the crystalline α_c-process on the morphology of semi-crystalline polymers: a comparative SAXS study on poly-є-caprolactone and polyethyleneoxide — •Anne Seidlitz, Albrecht Petzold, and Thomas Thurn-Albrecht — Institut für Physik, Martin-Luther-Universität Halle-Wittenberg, 06120 Halle (Saale)

Semi-crystalline polymers can be classified into two different types, depending on the presence (α_c-mobile) or absence (crystal-fixed) of the α_c-Relaxation, which provides mobility to the chains in the crystals. Starting from a hypothesis made by Boyd, that all polymers with a high crystallinity are α_c-mobile while all polymers with a low crystallinity are crystal-fixed, we investigated the morphology of polyethyleneoxide (PEO) 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 at different molecular weights and crystallization temperatures. A simulation based on the paracrystalline model was developed to derive quantitative morphological information from the SAXS data. Clear differences between the structure of PCL and PEO were observed. For PCL the crystalline thickness d_c is well defined, while the amorphous thickness d_a displays a broad distribution. PEO shows a small, well defined d_a and a broad thickness distribution of the crystalline lamellae. Our interpretation is that the crystalline lamellae in PEO can reorganize during crystallization until a minimal d_a is established, while the morphology of PCL corresponds to a quenched state resulting directly from the crystal growth process.