* The abstracts are available for each conference contribution when you click on the corresponding title.
June 09, 2005
7:00 – 8:15
Registration
8:15 – 8:30
Welcome
8:30- 9:00
Flow of viscoelastic liquids through fixed beds of particles
Autors:
I. Machač a), H. Bendová b) and B. Šiška c)
Affiliation:
University of Pardubice, Chemical Engineering Department, Faculty of Chemical Technology, nám. Čs. legií 565, 532 10 Pardubice, Czech Republic.
Contacts:
a) Corresponding author:
b)
c)
Abstract:
In this contribution, some basic ideas on modelling the flow of viscoelastic fluids through fixed beds of particles and porous media and the results of new pressure drop measurements in the creeping flow of different viscoelastic polymer solutions through fixed beds of spherical and non-spherical particles are presented. Analysing the experimental data, the modified forms of the Deborah number corrective function has been proposed for engineering estimation of the pressure drop excess.
Ivan Machač | University of Pardubice | Czech Republic
9:00 – 9:30
Power consumption of agitators in non-Newtonian fluids
Autor:
F. Rieger
Affiliation:
Czech Technical University in Prague, Faculty of Mechanical Engineering, Department of Process Engineering,Technická 4, 166 07 Prague 6, Czech Republic.
Contact:
Corresponding author:
Abstract:
The subjects of this contribution are methods for the determination of the agitator power consumption in non-Newtonian fluids. The power consumption can be calculated for known rheological behavior of mixed fluid or stated on the basis of measurements on small-scale mixing equipment with given fluid. The small-scale model of mixing equipment can be also used for determination of rheological behavior of concentrated non-Newtonian suspensions.
František Rieger | Czech Technical University in Prague | Czech Republic
9:30 – 10:00
Colloidal rheology of zirconia and zirconia-alumina mixed suspensions
Autors:
J. Andertová a) and I. Zedníková b)
Affiliation:
Department of Glass and Ceramics, Institute of Chemical Technology Prague, Technická 5, 166 28, Prague 6, Czech Republic.
Contacts:
a) Corresponding author:
b)
Abstract:
The work deals with the study of the colloidal rheology of aqueous yttria-doped zirconia and yttria-doped zirconia-alumina suspensions used for the preparation of ceramic materials by slip casting into porous moulds. Ceramic particles are naturally positive or negative charged depending on the pH conditions, the charge is measured via the zeta potential (ζ – potential). The point at which the ζ – potential is zero is as the isoeletric point –IEP – termed. The variation of rheological properties with pH and anion type correlated with the change in surface properties of zirconia. When designing ceramic suspensions with controlled properties it is necessary to have knowledge of the IEP. Two methods of IEP determination, based on the rheological behaviour (determination of the viscosity and the yield stress of the suspensions), are compared. The results obtained are compared with IEP determinations via ζ – potential measurements by the ESA method. The influence of the alumina content in the zirconia-alumina suspensions and the solid phase contents on the measured dependence is studied. The method proposed enables easy IEP determination of suspensions and the realistic assessment of pH ranges appropriate for the selected shaping technique.
Jana Andertová | Institute of Chemical Technology Prague | Czech Republic
10:00 – 10:30
Stability of a non-Newtonian film flow down an inclined plane
Autor:
J. Tihon
Affiliation:
Institute of Chemical Process Fundamentals, Academy of Sciences of the Czech Republic, 16502 Prague 6, Czech Republic.
Contact:
Corresponding author:
Abstract:
The experimental study of non-Newtonian film flows along an inclined plate is presented. The results obtained demonstrate the effects of fluid elasticity and shear thinning on the flow stability and the wave characteristics. Elasticity driven instabilities observable at low inclination angles and low flow rates is discussed.
Jaroslav Tihon | Institute of Chemical Process Fundamentals, Academy of Sciences of the Czech Republic | Czech Republic
10:30 – 11:00
Cofee break & Exhibition
11:00 – 11:30
Phase structure development in flowing polymer blends
Autor:
I. Fortelný
Affiliations:
Institute of Macromolecular Chemistry, Academy of Sciences of the Czech Republic, Heyrovského nám. 2, 162 06 Praha 6, Czech Republic.
Joint Laboratory “Polymer Materials” of Tomas Bata University in Zlín and the Institute of Macromolecular Chemistry AS CR, Heyrovského nám. 2, 162 06 Praha 6, Czech Republic.
Contact:
Corresponding author:
Abstract:
State of art in description of the phase structure development in polymer blends is discussed. It is shown that no theory provides reasonable prediction of the phase structure type in polymer blends as a function of their composition, rheological properties of the components and mixing conditions. Recent progress in description of the droplet breakup and coalescence is discussed. It is shown that graphic solution of the equation, describing the dynamic equilibrium between the droplet breakup and coalescence in monodispersed systems, provides reasonable qualitative dependence of the average droplet size in steady flow on parameters of the system.
Ivan Fortelný | Institute of Macromolecular Chemistry, Academy of Sciences of the Czech Republic | Czech Republic
11:30 – 12:00
On the predictive/fitting capabilities of XPP and PTT-XPP constitutive equations for branched LDPE melts
Autors:
R. Pivokonský 1, a), M. Zatloukal 2, b) and P. Filip 1, c)
Affiliations:
1) Institute of Hydrodynamics, Academy of Sciences of the Czech Republic, Pod Paťankou 5, 166 12 Prague, Czech Republic.
2) Tomas Bata University in Zlín, Polymer Centre, TGM 275, 762 72 Zlín, Czech Republic.
Contacts:
a) Corresponding author:
b)
c)
Abstract:
The predicting capabilities of two molecular-based constitutive equations (eXtended Pom-Pom (XPP) model, PTT-XPP model) were examined using two highly branched LDPE materials (Escorene LD 165 BW1 [Exxon, USA] and Bralen RB 0323 [Slovnaft, Slovakia]). Advanced rheometric expansion system (ARES) Rheometrics rheometer was used for measurement of linear viscoelastic properties of both materials (storage G’ and loss G” moduli), with the implementation of the SER Universal Testing Platform (SER-HV-A01) from Xpansion Instruments for determination of the uniaxial extensional viscosity. Shear data was obtained from capillary rheometer (RH7-2, Rosand Precision Ltd.) and from oscillatory measurements
(using Cox-Merz rule). Both model proved very good predicting/fitting capability for description of the steady and transient extensional viscosities. It has been found that the XPP model prediction is in a good agreement with an experimental steady-state shear viscosity data whereas the PTT-XPP model failed in this case. However, it has been revealed that a very good ‘coincidence’ with the experimental data can be achieved if an additional slip parameter in the PTT-XPP model is employed.
Radek Pivokonský | Institute of Hydrodynamics, Academy of Sciences of the Czech Republic | Czech Republic
12:00 – 12:30
EFFECTS OF γ-IRRADIATION ON RHEOLOGICAL PROPERTIES OF ULTRA-HIGH MOLECULAR WEIGHT POLYETHYLENE MELTS
Autors:
J. Mikešová a) and M. Nevoralová
Affiliation:
Institute of Macromolecular Chemistry, Academy of Sciences of the Czech Republic, Heyrovský Sq. 2, 162 06 Praha 6, Czech Republic.
Contact:
a) Corresponding author:
Abstract:
The wear of UHMWPE components in orthopaedic implants is still considered to be the main problem in arthroplasty. To increase the wear resistance of components, several methods of crosslinking and long-term stabilization of the polymer in the molten state were investigated in
the last years. Despite the desirable role of rheological properties of irradiated UHMWPE in the above processes, no information was found in the literature.
To analyze the effect of irradiation conditions (dose, dose-rate and atmosphere) on rheological behaviour of UHMWPE melts, a study was carried out on the polymers irradiated in the solid state. Linear viscoelastic characteristics of the molten polymers were used for the evaluation of
simultaneous crosslinking and degradation process in the polymer. The predominant mechanism in the process was strongly influenced by the irradiation dose. Increased values of the complex viscosity and storage modulus, indicating a crosslinking process were obtained for low irradiation doses. The rheological characteristics of polymers irradiated with doses higher than 50 kGy decreased with increasing dose as a consequence of degradation and they were considerably dependent on the irradiation dose-rate. On the other hand, no significant effect of the used irradiation atmosphere was found. An intensive increase in elasticity during the heat treatment was observed in the polymers irradiated with high doses; nevertheless, the level of elasticity reached after melt annealing was still lower than the elasticity of non-irradiated polymer.
Jana Mikešová | Institute of Macromolecular Chemistry, Academy of Sciences of the Czech Republic | Czech Republic
12:30 – 14:00
Lunch & Exhibition
14:00- 14:30
On the number of parameters in the empirical constitutive equations
Autors:
P. Filip a) and J. David b)
Affiliation:
Institute of Hydrodynamics, Academy of Sciences of the Czech Republic, Pod Patankou 5, 166 12 Prague 6, Czech Republic.
Contacts:
a) Corresponding author:
b)
Abstract:
A number of parameters appearing in the ‘classical’ empirical constitutive equations usually oscillates between two and five. With the onset of new rheologically more complex materials this range (two to five) is no longer tenable, and more empirical parameters are required for a proper description of the flow curves. The present paper tries to analyse this problem for the cases shear viscosity vs. shear rate and shear viscosity vs. shear stress.
Petr Filip | Institute of Hydrodynamics, Academy of Sciences of the Czech Republic | Czech Republic
14:30- 15:00
Viscosity of suspensions in electric field
Autors:
A. Lengalova a), V. Pavlinek b) and P. Saha c)
Affiliation:
Tomas Bata University in Zlín, Polymer Centre, TGM 275, 762 72 Zlín, Czech Republic.
Contacts:
a) Corresponding author:
b)
c)
Abstract:
The paper follows qualitative aspects of the dependence of some silicone-oil-based electrorheological (ER) fluids viscosity on geometry of particles, their dielectric properties, and strength of electric field. The study shows that the response of large, flaky particles to the field is most pronounced, round and smooth-surface granules have the lowest reaction. The variation in permittivities below and above relaxation frequency is decisive for the prediction of ER response of polyaniline-coated particles in the suspensions – the higher the difference, the stronger the ER effect.
Anežka Lengálová | Tomas Bata University in Zlin | Czech Republic
15:00 – 15:30
Pressure-temperature dependencies of viscosity behaviour of polymer melts
Autors:
T. Sedlacek a), M. Zatloukal b) and P. Saha c)
Affiliation:
Tomas Bata University in Zlín, Polymer Centre, TGM 275, 762 72 Zlín, Czech Republic.
Contacts:
a) Corresponding author:
b)
c)
Abstract:
Shear and elongational viscosities of selected polymeric materials were tested on a modified capillary rheometer. The addition of a backpressure device to capillary rheometer enabled increase of pressure in the polymer melt up to 100 MPa, which allowed evaluation of its effect on the flow behaviour. The obtained viscosity values at different pressure and temperature conditions were evaluated through pressure and temperature coefficients. PVT data was analyzed by the help of the Simha-Somcynsky equation of state (SS EOS). The modified Doolittle relationship was tested for connection of pressure-temperature dependent viscosity and thermodynamical parameters of SS EOS. Proposed interconnection proved to be a good tool for linearization of PVT and rheological data.
Tomáš Sedláček | Tomas Bata University in Zlin | Czech Republic
15:30 – 16:00
Modeling of polymer processing in area of highly non-linear viscoelasticity
Autors:
M. Zatloukal a) and P. Saha
Affiliation:
Polymer Centre, Faculty of Technology, Tomas Bata University in Zlin, TGM 275, 762 72 Zlin, Czech Republic.
Contact:
a) Corresponding author:
Abstract:
Fully viscoelastic FEM together with flow visualization technique are employed to quantify the effect of the die design on the wave type of interfacial instabilities in coextrusion. It has been shown experimentally that the minor channel geometry has a strong impact on the wave type of interfacial instabilities and the results can be correlated through novel criteria called as Total Stress Difference (TSN), which takes in to account the bulk change of the total stress in normal as well as tangential direction with respect to the interface.
Martin Zatloukal | Tomas Bata University in Zlin | Czech Republic
16:00 – 18:00
Poster section & Excursion to Rheology Lab at Tomas Bata University in Zlin
Rheological behaviour of viscoelastic paste for preparation bioceramic
Autors:
I. Zedníková 1, a), J. Andertová 1, b), P. Štern 2, c) and F. Rieger 3, d)
Affiliations:
1) Department of Glass and Ceramics, Institute of Chemical Technology, Technická 5, Prague 6, CZ-16628 , Czech Republic.
2) Institute of Hydrodynamics, Academy of Sciences of the Czech Republic, Prague 6, CZ-16612, Czech Republic.
3) Department of Process Engineering, Faculty of Mechanical Engineering, Czech Technical University in Prague, Prague 6, CZ-16607, Czech Republic.
Contacts:
a) Corresponding author:
b)
c)
d)
Abstract:
The main topic of this work is the preparation of resorbable bioceramic materials on a tricalciumphosphate basis. These materials are determined for reparations of bone tissues. There have been two technologic projects of the regulated porosity materials preparation issued. The procedure of porous material preparation has been studied for two types of original compounds on a tricalciumphosphate basis, four types of paste on polysaccharide basis and finally two types of additions of creator pores. The temperature dependence of viscoelastic behavior of original systems (ceramic paste and high concentrated suspension) using the oscillatory dynamic rheometry method has been studied as well.
Ivana Zedníková | Institute of Chemical Technology | Czech Republic
Rheological study of hyaluronic solutions
Autors:
M. Chytil 1, 2, a) and M. Pekař 1, b)
Affiliations:
1) Institute of Physical and Applied Chemistry, Faculty of Chemistry, Brno University of Technology, Purkyňova 118, 612 00 Brno, Czech Republic.
2) CPN Ltd., 561 02 Dolní Dobrouč 401, Czech Republic.
Contacts:
a) Corresponding author:
b)
Abstract:
The objective of this study was rheological investigation of buffered water solutions of a bacterially produced hyaluronic acid (HA, in the form of sodium salt) and its hydrophobically modified derivatives (hHA). The hydrophobization was carried out by attachment of alkyl chains of various lengths and with different substitution degrees to the polysaccharide backbone. It is shown that hyaluronic acid possesses more profound non-Newtonian shear thinning flow behavior and higher apparent viscosity at comparable concentrations and conditions than its most alkyls containing derivatives. Thus, we report about a strong hydrophobization effect on the HA rheological behavior. Furthermore, temperature and ionic strength influences on solutions of HA and its derivatives were studied too, as well as some dynamic oscillatory experiments on these solutions.
Martin Chytil | Brno University of Technology | Czech Republic
PP/PET blends: modification and flow properties
Autors:
N. Honková a), B. Hausnerová b), T. Kitano c) and P. Sáha d)
Affiliation:
Tomas Bata University in Zlín, Polymer Centre, TGM 275, 762 72 Zlín, Czech Republic.
Contacts:
a) Corresponding author:
b)
c)
d)
Abstract:
The objective of the presented work is to evaluate the effect of modification on the rheological behaviour of polymer blends based on polypropylene (PP) and polyethylene terephthalate (PET). These systems attract considerable attention since collective processing (without any
separation process) of such significant waste materials combined with the proper compatibilisation represents a convenient method of re-using the scrap material, thereby alternating traditional recycling technologies such as landfilling or incineration. The discussion of rheological properties of PP/PET systems involves the effects of matrix type, morphology, blend composition, compatibilisation attained in different ways (one- and two- step in situ reactive techniques), elastomeric modification, temperature, and comparison between results of measurements performed at steady state and oscillatory shear flows.
Natálie Honková | Tomas Bata University in Zlín | Czech Republic
Self-reinforcement of polymers as a consequence of flow-induced crystallization
Autors:
M. Obadal a), R. Čermák b), K. Stoklasa c) and V. Habrová d)
Affiliation:
Tomas Bata University in Zlín, Faculty of Technology, Department of Polymer Engineering TGM 275, 762 72 Zlín, Czech Republic.
Contacts:
a) Corresponding author:
b)
c)
d)
Abstract:
Self-reinforcement is a material-based effect through which a conventional polymeric material acquires excellent mechanical and thermal properties. In this work, structure and resulting properties of self-reinforced high-density polyethylene were studied rigorously. Multiscale
morphology observations showed uniquely fibrous arrangement, high crystallinity and molecular orientation degree of self-reinforced extrudates. Consequently, the self-reinforced specimens possess unique mechanical and thermal properties.
Martin Obadal | Tomas Bata University in Zlín | Czech Republic
Apparent wall slip of tungsten carbide based feedstock for powder injection moulding
Autors:
R. Slezák a), B. Hausnerová b) and P. Sáha c)
Affiliation:
Tomas Bata University in Zlín, Polymer Centre, TGM 275, 762 72 Zlín, Czech Republic.
Contacts:
a) Corresponding author:
b)
c)
Abstract:
In this paper, wall slip behaviour of highly filled WC-Co compounds during capillary flow was studied. The relationship between slip velocity and wall shear stress was fitted by power-law. The compound containing 30 vol. % of the filler exhibited approximately ten times higher slip velocities than that filled with 40 vol. % of the powder. Concerning contribution of slip to total volumetric flow, it decreased with increasing shear stress and increasing capillary diameter. In addition, slipping contributed to the flow of the 30 vol. % system more significantly, and plug flow at low shear stresses occurred.
Radek Slezák | Tomas Bata University in Zlín | Czech Republic
Theoretical and experimental analysis of viscoelastic polymer melt extrusion
Autors:
K. Chaloupkova a) and M. Zatloukal b)
Affiliation:
Polymer Centre, Faculty of Technology, Tomas Bata University in Zlin, TGM 275, 762 72 Zlin, Czech Republic.
Contacts:
a) Corresponding author:
b)
Abstract:
Die drool phenomenon, occurring as a result of the viscoelastic behavior during the flow of the polymer melts, has been experimentally investigated for metallocene based LLDPE on the specially designed annular extrusion die with the capability to control the stress state at the end
of the die by the help of specific type of cooling system. With the aim to understand the die drool phenomenon in more detail, the flow at the end of the die has been analyzed theoretically by the Finite Element Method (FEM) employing modified White-Metzner model as the constitutive equation. It has been revealed that the negative pressure occurs at the die lip area which seems to be driving factor for the die drool phenomenon.
Kateřina Chaloupková | Tomas Bata University in Zlín | Czech Republic
Electrorheological properties of silica modified with polyaniline
Autors:
V. Pavlínek 1, a), A. Lengálová 1, b), P. Sáha 1, c), O. Quadrat 2, d) and J. Stejskal 2, e)
Affiliations:
1) Tomas Bata University in Zlín, Polymer Centre, TGM 275, 762 72 Zlín, Czech Republic.
2) Institute of Macromolecular Chemistry, Academy of Sciences of the Czech Republic, 162 06 Prague 6, Czech Republic.
Contacts:
a) Corresponding author:
b)
c)
d)
e)
Abstract:
Electrorheological properties of silicone-oil suspensions of silica particles coated with polyaniline base together with frequency spectra of dielectric characteristics have been investigated. The results suggest that the interfacial polarization of particles is predominantly controlled by polarizability of their surface layer, and the influence of the surface layer thickness is of secondary importance.
Vladimír Pavlínek | Tomas Bata University in Zlín | Czech Republic
June 10, 2005
8:30 – 11:00
Excursion to Fatra Napajedla company
12:00
End of the conference