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Measurement and evaluation of elongational viscosity of selected biomaterials
Šustková, Hana ; Krakovský, Ivan (advisor) ; Fortelný, Ivan (referee)
Measurement and evaluation of elongational viscosity of selected biomaterials Bachelor thesis abstract Hana Šustková 20.5.2011 This thesis analyzes the elongational viscosity of the biomaterials. The basic concepts related to the issue of measurement of shear and elongational viscosity of melts in particular focusing on the SER rheometer, which was used in the experiment, were presented. With SER rheometer elongational viscosity of BioFlex samples of BioFlex, PA6 and their mixtures at temperatures of 225o C and 235o C for ten Hencky different strain rates from 0.1 to 10 s−1 were studied. In the experiment rectangular specimens prepared for different content of Bioflex and Polyamide PA6 were used. Based on the data presented in this thesis some features of the internal structure of used bio- material, and its possible practical applications, further and qualitative changes in its properties in the mixture were described. It was shown that the linear viscoelastic response of BioFlex is two orders of magnitude below in comparison to the response of PA6 and in the temperature range the linear viscoelastic response does not change. It is shown that in mixtures with BioFlex and PA6 the BioFlex shows a signifi- cant proportion of the linear viscosity range - and at low concentrations of BioFlex in comparison to PA6...
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On the electrospinning of PVB solutions
Švrčinová, Petra ; Filip, Petr ; Lubasová, D.
Extension rheological characteristics belong to the principal description of polymer jet formation during a process of electrospinning. However, in spite of nearly absence of shear deformation of polymer solutions during the process of their spinnability, it seems that shear electrorheological characteristics can serve as an indicator of good or bad quality of an electrospun template. The experiments were carried out with four polyvinylbutyral (PVB) solutions in concentration of 10 wt%. Shear viscosities in absence (η0) and presence (η) of electric field were measured using a rotational rheometer equipped with an electrorheological cell. It was shown that the good solvents of PVB exhibit an almost constant curve of η/η0 vs. electric field strength, whereas the viscosity curves for the poor solvents exhibit enhancement. This enhancement corresponds to better quality of electrospun templates (obtained for polymer solutions of PVB with poor solvents).
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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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