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Polyvinyl chloride filled with bismuth oxychloride powder
Polášková, M. ; Sedláček, T. ; Kharlamov, Alexander ; Pivokonský, Radek ; Saha, P.
Mixing of polymers with radiopaque agents enables the polymers visibility on X-ray images and represents the easiest way to accurately locate the polymeric surgical device during a critical procedure. Medical-grade polyvinyl chloride was compounded with various amounts of bismuth oxychloride, chosen for its unique properties such as high radiopacity, non-toxicity, excellent chemical and physical stability and good dispersibility in the polymeric matrix. Micro-compounder Haake MiniLab II, consisting of a conical co-rotating twin-screw compounder with an integrated backflow channel, was used for melt mixing and simultaneously for rheological measurement. Rheological data received from micro-compounder were supplemented and correlated with the data obtained from Anton Paar rotational rheometer. Structure of prepared composites was studied by scanning electron microscopy, and their thermo-mechanical properties were tested using dynamic mechanical analysis.
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Vliv reakčního vytlačování na reologické vlastnosti metalocénových polypropylénů
Pivokonský, Radek ; Zatloukal, M. ; Filip, Petr ; Tzoganakis, C.
Constitutive equations represent a powerful tool for analysis and description of linear and branched polymer materials (even for polydisperse ones). Predictive/fitting capabilities of three constitutive models (eXtended Pom-Pom, PTT-XPP, and modified Leonov models) were examined using four standard industrial PE materials (two linear and two branched). All the materials were tested in both shear and uniaxial extensional flows (steady and transient). Advantages/disadvantages of the individual models to the individual types of materials are discussed and experimentally documented. Konstituční rovnice představují účinný nástroj pro analýzu a popis lineárních a rozvětvených polymerních materiálů. Jsou porovnány možnosti popisu a predikce tří konstitučních rovnic (XPP, PTT-XPP a modifikovaného Leonovova modelu) při aplikaci na čtyři standartní PE materiály (dva lineární a dva rozvětvené). Testování proběhlo jak ve smykovém tak v elongačním toku. Jsou diskutovány výhody a nevýhody jednotlivých modelů.
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