Regensburg 2004 – wissenschaftliches Programm

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CPP: Chemische Physik und Polymerphysik

CPP 15: POSTER: Polymers and Biomaterials

CPP 15.33: Poster

Dienstag, 9. März 2004, 17:00–19:00, B

Phase Diagram and Morphologies of Crystalline/Crystalline Poly (Vinylidene Fluoride)/Poly (3-Hydroxybutyrate) Blends — •Jieping Liu and Bernd-J Jungnickel — Deutsches Kunststoff-Institut, Schlossgartenstr. 6, D-64289 Darmstadt, Germany

The melting point depression and a single glass transition in the phase diagram evidence that PVDF and PHB are completely miscible in the melt. PVDF crystallizes first and PHB second upon cooling. At isothermal two-step crystallization, the components behave quite different. Crystallization temperature and rate, respectively, of PVDF decrease with increasing PHB content since PHB acts as a diluent; the PVDF crystallization is ruled only by crystallization temperature and initial composition. In contrast, PHB crystallization depends on the already existent PVDF morphology since PHB may be included in or rejected from the PVDF spherulites depending on the PVDF crystallization temperature. The inclusion of PHB into PVDF dendrites reduces the available dimension for PHB crystal growth (Avrami exponent n = 2) whereas the PHB crystallizes undisturbed tri-dimensionally with athermal nucleation in the surroundings of globular PVDF spherulites (n = 3). At a given temperature, the crystallization rate of PHB inside the PVDF spherulites is distinctly larger than that of PHB outside. These results underline the microscopic findings on the complex supermolecular structure in that blend.