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A note to the measurement of extensional viscosity using SER Universal Testing Platform with different shapes of polymer samples
Švrčinová, Petra ; Filip, Petr ; Kharlamov, Alexander
For polymer melts, with respect to their numerical simulations, there were recommended to apply polymer samples (rectangles) with a width not exceeding 8 mm and a thickness less than 0.4 mm. The aim of this contribution is to document - for material used (LDPE Escorene, Exxon, USA) - the invariantness of the elongational viscosity measured with respect to sample dimensions including its width and thickness. The width of the samples used consecutively attained 12.7, 11.0, 9.3, and 7.4 mm; the thickness also ranged across a sufficiently broad interval (0.3-1.1mm). Temperature was set to 180, 190, and 200oC. For the measurements there were used the SER Universal Testing Platform from the Xpansion Instruments; the model SER-HV-P01 was applied with a Physica MCR501 rotational rheometer host system. The results obtained justify usage of a 'classical' width 12.7 mm (1/2") more suitable for better manipulation with a sample, especially its fixing to both drums perpendicularly to the clamps.
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Polyvinyl chloride catheters with repressed migration of plasticizers
Sedláček, T. ; Polášková, M. ; Kašpárková, V. ; Filip, Petr ; Sáha, P.
Impart flexibility and desired softness of polyvinylchloride (PVC) – one of the most widely used polymeric materials for medical device production – is achieved by addition of appropriate amount of plasticizer, usually di(2-ethylhexyl phthalate) (DEHP), into polymer matrix. DEHP is not chemically bonded to PVC and migrates to the surrounding media such as saliva, blood, plasma, or serum resulting in several toxic effects. Migration of DEHP can be significantly suppressed by embedding PVC into another polymer preventing its direct contact with surrounding liquid media. Coextruded TPU-PVC-TPU catheters were prepared with various thicknesses of TPU layers to evaluate its repressing effect on DEHP releasing. Releasing kinetic of DEPH from both three layered catheters and PVC catheters into the acetonitrile was observed in various time intervals and determined using reverse-phase liquid chromatographic technique.
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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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A note to the tube theory
Kharlamov, Alexander ; Filip, Petr ; Švrčinová, Petra
The classical Doi-Edwards (DE) model represents a basic issue for tube theories. The model describes dynamics of polymer strands between entanglements and predicts stress in linear polymers. In this contribution there is considered the dynamics of the whole molecules within the same tube picture. When the molecule end-to-end vector is considered as a Hookean spring the damping function shows weaker thinning. The presented model describes one of the possible mechanisms leading to weaker damping exhibited by branched polymers.
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Powder injection moulding of a ceramic part
Hausnerová, B. ; Marcaníková, L. ; Filip, Petr
The aim of the study is to optimize the production of alumina ceramic parts via Powder Injection Moulding (PIM) technology. As a case study fabric with main demand on surface-roughness tolerances has been selected with the potential of high production quantities for textile machines industry. The process is searched in terms of material tailoring, part design and dimensions, and processing conditions of injection moulding, debinding and sintering steps. Rheological, thermal and pressure-volume-temperature characteristics were measured in order to provide the reliable data for the simulation of injection moulding as well as thermal and thermogravimetric analyses have been carried out to attain non-porous final sintered products.
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