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CPP: Fachverband Chemische Physik und Polymerphysik
CPP 35: Poster Session II
CPP 35.31: Poster
Wednesday, March 29, 2023, 11:00–13:00, P1
Long chain Polyamides: Influence of methylene sequence length and external forces on structural features — •Rene Sattler1,2, Varun Danke3, and Mario Beiner1,2 — 1Fraunhofer IMWS, Walter-Hülse-Str. 1, D-06120 Halle (Saale), — 2Martin-Luther-Universität Halle-Wittenberg, Naturwissenschaftliche Fakultät II, D-06099 Halle (Saale) — 3Evonik Operations GmbH, Research Development & Innovation, Paul-Baumann-Str. 1, D-45722 Marl
Crystallographic studies towards the influence of methylene sequence length on a series of even-even polyamides PA 10.n (with n = 12, 14, 16 and 18) are performed. Temperature-dependent X-ray diffraction measurements show that the triclinic α phase is the preferred phase at room temperature after slow cooling from melt. In PA 10.12 and PA 10.14 a reversible Brill transition to the (pseudo)hexagonal high temperature γ phase is observed. However, the Brill transition temperature is strongly dependent on n and shifting to higher temperatures with increasing methylene sequence length. For the two higher members a Brill transition is absent. The analysis of annealed, uniaxial oriented fibers reveals that the crystalline state achieved under ambient conditions is influenced by external forces. This is due to relatively small energetic differences between the α and β polymorphs. All the uniaxial oriented PA 10.n samples show a β polymorph which is most prominent for PA 10.12 and PA 10.14. The higher members show a mixture of the β polymorph superimposed with a certain franction of the α polymorph.