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Choice of polymer samples geometry for measurement of elongational viscosity using ser universal testing platform
Filip, Petr ; Švrčinová, Petra
Generation of purely uniaxial elongational flow of polymer melts is very uneasy problem. It seems that each hitherto developed device for measurement of uniaxial elongational viscosity also produces - to some extent - a planar flow. During the last period there has been questioned - based on this reasoning - the applicability of a SER Universal Testing Platform and was recommended the range of rectangular dimensions of polymer samples for which measurements of uniaxial elongational viscosity is possible to take into account. The aim of this contribution consists in verification of invariantness of uniaxial elongational measurements using the SER Universal Testing Platform with respect to the dimensions of polymer samples applied. There is shown that for sufficiently broad region of admissible widths and thicknesses the results are identical. For these measurements there was used LDPE Escorene (Exxon, U.S.A.).
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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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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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Určení objemového průtoku vazkoplastických kapalin mezikružím za pomoci aditivní metody
Filip, Petr ; David, Jiří
An additive method enabling a direct determination of axial flow rate for viscous (power-law model) and viscoplastic (Vočadlo model) fluids in concentric annuli is presented. Flow rate through the actual concentric annulus is possible to express as a sum of axial flow rates through individual partial concentric annuli forming the whole annulus. The resulting relation for axial flow rate is possible to express in analytical forms without necessity of otherwise complicated derivations. The only numerical calculation consists in a determination of location of a zero shear stress for the original whole concentric annulus.
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Poznámka k reptační teorii
Kharlamov, Alexander ; Filip, Petr ; Švrčinová, Petra
Avoiding the Independent Alignment (IA) approximation in the classical Doi-Edwards model causes the computation extremely time and hardware consuming. Nevertheless some flow situations cannot be modelled with the IA approximation. This contribution presents a probabilistic approach not taking into account the IA approximation.
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Měření elongační viskozity PE materiálů
Švrčinová, Petra ; Kharlamov, Alexander ; Filip, Petr
This contribution aims at the measurements of elongation viscosity for polyethylene materials. The approach is analysed from the viewpoint of possible degradation of materials tested and the emphasis is paid to admissible acceleration of the whole measuring process. There is presented a hint how to simplify (and accelerate) the measurements for a suitable class of materials.
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