* The abstracts are available for each conference contribution when you click on the corresponding title.
July 27, 2011
7:00 – 8:20
Registration
8:20 – 8:30
Welcome
NOVEL RHEOLOGICAL TECHNIQUES I
(Chairman: Helmut Münstedt)
8:30 – 9:00
Probing Nonlinear Viscoelasticity of Polymer Melts by Medium Amplitude Oscillatory Shear (MAOS)
Autors:
Manfred H. Wagner and Víctor Hugo Rolón-Garrido
Affiliation:
Chair of Polymer Engineering/Polymer Physics, Berlin Institute of Technology (TU Berlin), Fasanenstrasse 90, D-10623 Berlin, Germany
Abstract:
MAOS is shown to be a powerful tool to investigate the inception of nonlinear viscoelasticity of polymer melts. A constitutive analysis based on a general single integral constitutive equation, which includes the Doi-Edwards model without (DE) and with independent alignment assumption (DE IA) as well as the molecular stress function (MSF) model, confirms two important scaling relations found experimentally by Hyun and Wilhelm: (1) The relative intensity of the 3rd harmonic compared to the 1st harmonic scales with the square of the strain amplitude according. Consequently, a new nonlinear coefficient, the so-called intrinsic nonlinearity was introduced. (2) In the terminal relaxation regime, the intrinsic nonlinearity scales with the square of the angular frequency, and was found to be a very sensitive measure regarding molecular topology by identifying and separating relaxation processes in model branched polymers. We show that the nonlinear viscoelastic moduli can be expressed as sums of their linear-viscolelastic counterparts at angular frequencies of ω, 2ω, and 3ω. The absolute value of the intrinsic nonlinearity depends on the difference (α – β) between the 3rd order orientational effect (parameter α) according to the DE or DE IA model and the 2nd order isotropic stretching effect (parameter β) according to the MSF model.
The measured apparent values of the intrinsic nonlinearity measured in parallel-plate geometry are rescaled in order to take the non-uniform shear deformation into account, and are compared to constitutive models. While both the DE and DE IA model fail to describe the experimental data, the data of linear and comb-like PS melts are quantitatively described by the MSF model. However, the model predicts a plateau at the level of the maximum of the experimental data, while for comb polymers with entangled branches, a minimum in the intrinsic nonlinearity is observed, followed by a second increase of the intrinsic nonlinearity at higher frequencies, which correspond to the terminal relaxation times of the branches. Surprisingly, this can be modelled quantitatively if only the terminal relaxation modes of the backbone and the branches are assumed to be deforming non-affinely and to respond to the nonlinearity.
Keywords: Fourier Transformation (FT) rheology, Medium Amplitude Oscillatory Shear (MAOS), Doi-Edwards model, Molecular Stress Function (MSF) model, monodispers linear polystyrene, styrene comb polymers.
Manfred H. Wagner | TU Berlin | Germany
9:00 – 9:30
Experimental Investigation of Die Drool and Slip-Stick Phenomena during HDPE Polymer Melt Extrusion
Autors:
Jan Musil 1, 2), Martin Zatloukal 1, 2), Tim Goughc 3) and Mike Martyn 3)
Affiliations:
1) Centre of Polymer Systems, Tomas Bata University in Zlín, nám. T. G. Masaryka 5555,760 01 Zlín, Czech Republic.
2) Polymer Centre, Faculty of Technology, Tomas Bata University in Zlín, nám. T. G. Masaryka 275, 762 72 Zlín, Czech Republic.
3) IRC in Polymer Engineering, School of Engineering, Design and Technology, University of Bradford, Richmond Road, BD7 1DP, Bradford, United Kingdom.
Abstract:
In this work, two slightly different batches of one commercial linear HDPE polymer melt were rheologically characterized and then extruded through two specially designed dies (annular and slit) in order to investigate die drool as well as slip-stick phenomena. Flow birefringence stress visualization inside the slit die was also performed. It has been revealed that lower elasticity and both shear and extensional viscosities reduce accumulated drool mass at the die exit face and also correlation between appearance and intensity of both slip-stick and die drool phenomena was discovered.
Keywords: Die drool, Slip-stick, Flow instabilities, Flow birefringence, Shear viscosity, Extensional viscosity, Extrusion.
Jan Musil | Tomas Bata University in Zlin | Czech Republic
9:30 – 10:00
Cofee break & Exhibition
NOVEL RHEOLOGICAL TECHNIQUES II
(Chairman: Víctor Hugo Rolon-Garrido)
10:00 – 10:30
AWS Viscometry – Principles and Applications
Autors:
Ondřej Wein 1), Marek Večeř 2), Jaroslav Tihon 1) and Věra Pěnkavová 1)
Affiliations:
1) Institute of Chemical Process Fundamentals of the ASCR, v.v.i.,Rozvojova 135, 165 02 Prague 6, Czech Republic.
2) VSB –Technical University of Ostrava, 17. listopadu 15/2172, 708 33 Ostrava-Poruba, Czech Republic.
Abstract:
Quantitative identification of Apparent wall slip (AWS) effect, accompanying the flow of colloidal dispersions in confined geometries, requires a specific modification of common viscometric methods. Essential distinction between common and AWS viscometry is outlined – including theoretical background, calibration, data acquisition, and downstream data treatment – and demonstrated for a class of rotational viscometers.
Keywords: AWS viscometry; Edge effects; Inertia effects.
Ondrej Wein | ICPF ASCR, Czech Republic | Czech Republic
10:30 – 11:00
On-Line Rheometry: a Tool to Monitor Polymer Nanocomposites Production
Autors:
S. T. Mould, S.P. Pereira, J. M. Barbas, J. M. Nóbrega, A. V. Machado and J. A. Covas
Affiliation:
Institute for Polymers and Composites/I3N, University of Minho, Campus de Azurém 4800-058 Guimarães, Portugal.
Abstract:
The high potential of polymer nanocomposites has attracted the interest of both industrial and scientific communities. The final properties of these materials depend not only on the characteristics of the matrix and nanofillers, but also on the degree of dispersion of the nanofiller in the polymeric matrix. There are different methods to promote the dispersion of nanofillers in polymeric matrices, but the most promising is based on melt mixing, where the dispersion is achieved through the application shear and elongational stresses on a mixture of the polymer melt and nanofiller, usually performed on complex mixing devices. In order to improve the knowledge of the phenomena involved in the melt mixing process, several research groups are developing on/in-line adequate monitoring techniques, among these the online rheometry has shown to be a suitable choice. This work presents a new accessory conceived for a previously developed automated on-line rheometry system, which allows to couple easily the rheometer to any extruder. The developed system was subsequently used to study the effect of some process parameters related to the melt mixing process, which evidences the adequacy of these tools for monitoring purposes.
Keywords: on-line rheometry, polymer nanocomposites, melt mixing, monitor production.
Joao Miguel Nobrega | University of Minho | Portugal
11:00 – 11:30
Planar Extensional Viscosity Measurements for LDPE Polymer Melt by Using Novel Orifice Die Design and Cogswell model
Autor:
Martin Zatloukal
Affiliation:
Centre of Polymer Systems, Polymer Centre, Tomas Bata University in Zlin, nam. T. G. Masaryka 5555, 760 01 Zlin, Czech Republic.
Abstract:
In this work, novel patent pending rectangle orifice die design has been proposed and tested for planar extensional viscosity measurements of extrusion coating LDPE through entrance pressure drop determination on conventional twin bore capillary rheometr. The obtained results have been compared with the corresponding uniaxial extensional viscosity data and different strain hardening level in both viscosities has been identified. It has been suggested that uniaxial and planar extensional viscosity measurements, utilizing novel orifice die design, can be considered as a very useful and simple tool to fulfill basic aims of the applied rheology.
Keywords: Orifice die, Planar extensional viscosity, Uniaxial extensional viscosity, Cogswell model, Entrance pressure drop, Polymer melts, Capillary rheometer.
Martin Zatloukal | Tomas Bata University in Zlin | Czech Republic
11:30 – 13:00
Lunch & Exhibition
RHEOLOGY OF POLYMERS, COMPOSITES AND BLENDS
(Chairman: Joao Miguel Nobrega)
13:00 – 13:30
Increase of Long-chain Branching by Thermo-oxidative Treatment of LDPE
Autors:
Víctor H. Rolón-Garrido, Jinji Luo and Manfred H. Wagner
Affiliation:
Chair of Polymer Engineering/Polymer Physics, Berlin Institute of Technology (TU Berlin), Fasanenstrasse 90, D-10623 Berlin, Germany.
Abstract:
Low-density polyethylene (LDPE) was exposed to thermal and thermo-oxidative treatment at 170°C, and subsequently characterized by linear-viscoelastic measurements and in uniaxial extension. The Molecular Stress Function (MSF) model was used to quantify the elongational viscosities measured. For the thermally treated samples, exposure times between 2 and 6 hours were applied. Formation of long-chain branching (LCB) was found to occur only during the first two hours of thermal treatment. At longer exposure times, no difference in the level of strain hardening was observed. This was quantified by use of the MSF model: the nonlinear parameter f2max increased from f2max=14 for the virgin sample to f2max=22 for the samples thermally treated between 2 and 6 hours. For the thermo-oxidatively treated samples, which were exposed to air during thermal treatment between 30 and 90 minutes, the level of strain hardening increases drastically up to f2max=55 with increasing exposure times from 30 up to 75 min due to LCB formation, and then decreases for an exposure time of 90 minutes due to chain scission dominating LCB formation. The nonlinear parameter β of the MSF model was found to be β=2 for all samples, indicating that the general type of the random branching structure remains the same under all thermal conditions. Consequently only the parameter f2max of the MSF model and the linear-viscoelastic spectra were required to describe quantitatively the experimental observations. The strain hardening index, which is sometimes used to quantify strain hardening, follows accurately the trend of the MSF model parameter f2max.
Keywords: Rheology, MSF model, shear flow, elongational flow, strain hardening, low-density polyethylene, polymer melts, thermal degradation, thermo-oxidative degradation.
Víctor Hugo Rolón-Garrido | TU Berlin | Germany
13:30 – 14:00
Behavior of Conductive Particle Networks in Polymer Melts under Deformation
Autors:
Zdeněk Starý, Johannes Krückel, Dirk Schubert and Helmut Münstedt
Affiliation:
Institute of Polymer Materials, Friedrich-Alexander University Erlangen-Nuremberg, Martensstr. 7, 910 58 Erlangen, Germany.
Abstract:
The electrical properties of the composites containing conductive fillers are given by the structure of the particle network. Therefore, the behavior of these networks under deformation in the molten state is of great interest in order to obtain materials with desirable electrical properties. In this work the composites containing carbon black or carbon fibers were exposed to a shear deformation in two different experimental modes – oscillation and creep and the electrical conductivity of the materials was measured simultaneously.
Keywords: polymer composites, rheology, conductivity.
Zdenek Stary | FAU Erlangen-Nuremberg | Germany
14:00 – 14:30
Phase Inversion of EPDM/PP Blends: Effect of Viscosity Ratio
Autors:
A.V. Machado 1), C.F. Antunesa 2) and M. van Duin 2)
Affiliations:
1) Institute for Polymers and Composites/I3N, University of Minho, 4800-058 Guimarães, Portugal.
2) DSM Research, P. O. Box 18, 6160 MD Geleen, The Netherlands.
Abstract:
EPDM/PP blends and TPVs with and without crosslinking, respectively, were prepared, in a batch mixer, using three different EPDM rubbers. EPDM/PP based TPVs were dynamic vulcanised using the resol/SnCl2 system. Samples were collected along the time in order to get information on the morphology evolution and crosslinking density during dynamic vulcanisation. The morphology was studied by SEM and the crosslink density by gel content. In the case of low viscosity EPDMs, crosslinking of the EPDM phase was retarded due to its low crosslinking efficiency. This delay on crosslinking reaction enables the observation of the various stages of the morphological mechanism that takes place during dynamic vulcanisation. It could be observed that phase inversion takes place via lamellar mechanism. More detailed insight on phase inversion mechanism during dynamic vulcanisation was accomplished.
Keywords: rheology, crosslinking, viscosity, dynamic vulcanisation.
Ana Vera Machado | University of Minho | Portugal
14:30 – 15:00
Cofee break & Exhibition
NON-NEWTONIAN FLUID MECHANICS
(Chairman: Petr Filip)
15:00 – 15:30
Interfacial Instabilities in a Two Layer Coextrusion during Cable Coating
Autors:
Birane Toure 1), Jiri Vlcek 2), Juan Marin 3) and Stig Jarle Hauko 4)
Affiliations:
1) Nexans Research Center 29, Rue Pré Gaudry-69353 Lyon cedex 07, France.
2) Compuplast International, Inc., Nerudova 158, 76001 Zlin, Czech Republic.
3) Cjtek, Rue des Uttins 30-1400 Yverdon, Switzerland.
4) Nexans Norway AS, Klingavn. 2, N-7800 Namsos Norway.
Abstract:
The paper describes a study leading to a modification of a coextrusion die. This modification stabilized the coextrusion process and removed instabilities observed on a cable produced on the original die.
Keywords: Coextrusion in polymers, polymer flow simulation, cable coating, sheathing, interfacial instabilities.
Jiri Vlcek | Compuplast International, Inc. | Czech Republic
15:30 – 16:00
An Evaluation of Mixing Quality of Three Different Types of Mixing Elements
Autors:
Pavel Kubik 1), Jiri Vlcek 2), Costas Tzoganakis 3) and Luke Miller 4)
Affiliations:
1) Department of Polymer Engineering, Faculty of Technology, Tomas Bata University in Zlín, Zlín, Czech Republic.
2) Compuplast International, Inc., Zlín, Czech Republic.
3) Department of Chemical Engineering, University of Waterloo, Waterloo, Ontario, Canada.
4) Xaloy Corporation, New Castle, Pennsylvania, USA.
Abstract:
In this paper, the performance of three different mixing elements on color dispersion in HDPE and LLDPE polymer melt stream during extrusion is studied. Two similarly designed Maddock mixers and a Stratablend II mixer are used as the last part of a general purpose single screw. Moreover, an in-line melt camera is used for quantification of mixing quality by visualization of grayscale of the color dispersion and thus mixing. The Stratablend II mixer produces the lowest and most uniform standard deviation, which is the best tool to characterize its excellent mixing performance. Both Maddock mixers showed the same trend but higher values of standard deviation. All results are then compared with a full 3D finite element method simulation. Simulations clearly indicate that Stratablend II mixer has the the best mixing abilities and that these are mainly given by its unique design with high average value of shear stress. The role of elongational stress does not appear to have a high influence on mixing for these mixers. The results also suggest that the key factor for achieving better mixing is the frequency with which a large fraction of the material passes through the high shear stress regions of the mixer.
Keywords: Inline Melt Camera, Mixing quantification, Maddock mixer, Stratablend II mixer, Grayscale, Standard Deviation, Shear Stress, Elongational Stress, Melt Temperature.
Pavel Kubik | Tomas Bata University in Zlin | Czech Republic
18:30
Conference dinner
July 28, 2011
NON-NEWTONIAN FLUID MECHANICS
(Chairman: Manfred H. Wagner)
8:00 – 8:30
Elastic Properties of Polymer Melts Filled with Nanoparticles
Autors:
Helmut Münstedt and Christian Triebel
Affiliation:
Institute of Polymer Materials, Department of Materials Science, Friedrich-Alexander-University Erlangen-Nürnberg, Martensstr. 7, D-91058 Erlangen, Germany.
Abstract:
The influence of silica nanoparticles on the elasticity of a polymethylmethacrylate (PMMA) melt was investigated. The extrudate swell obtained from the extrusion of the melt through a die and the recoverable deformation after a creep test were measured. As well known from other materials, the extrudate swell becomes smaller by adding fillers, i.e. the elasticity decreases. This is usually explained by the effect of substituting viscoelastic polymer molecules by rigid particles. The linear steady-state recoverable compliance Je, however, attains values which are significantly higher than those of the matrix indicating an increase of the elasticity. This effect is postulated to be due to interactions of the matrix molecules with the particle surface giving rise to longer retardation times and higher retardation strengths which lead to larger Je according to the theory of linear viscoelasticity. The apparent discrepancy between these two contrary effects is solved by the finding that the recoverable compliance becomes smaller with stress above a critical value and approaches the elasticity of the matrix. This decrease is found in a stress range which is much lower than that applied in the extrudate-swell experiment. The results of an elastic compliance becoming smaller with stress are interpreted by a detachment of the matrix molecules from the particles.
Keywords:Extrudate swell, steady-state elastic compliance, creep-recovery experiments, polymethylmethacrylate, silica nanoparticles, particle/matrix interaction, model.
Helmut Münstedt | Friedrich-Alexander-University Erlangen-Nürnberg | Germany
8:30 – 9:00
Extensional Rheology as Effective Tool for Characterization of Polymer Nanocomposites
Autors:
Milan Kracalik, Stephan Laske and Clemens Holzer
Affiliation:
Montanuniversitaet Leoben, Department Polymer Engineering and Science, Chair of Polymer Processing, Otto Gloeckel Str 2, 8700 Leoben, Austria.
Abstract:
Morphological characterization in polymer nanocomposites is usually performed using X-ray scattering and microscopic techniques, while the enhancement of processing and mechanical properties is commonly investigated by rotational as well as capillary rheometry and tensile testing. However, all of these techniques are time consuming and require expensive scientific equipment. A fast and efficient way of estimating the level of reinforcement in polymer nanocomposites can be performed by melt extensional rheology, because it is possible to correlate the level of melt strength with mechanical properties, which reflect both the 3D network formed by the clay platelets/polymer chains as well as final molecular structure in the filled system. The physical network made of silicate filler and polymer matrix has been evaluated by X-ray diffraction and transmission electron microscopy. Extensional rheometry and tensile testing have been used to measure efficiency of the compatibilizer amount in a polypropylene-nanoclay system and to evaluate the effect of processing conditions on polymer matrix reinforcement.
Keywords: Extensional Rheology, Reinforcement, Nanocomposites; Melt Compounding; Melt Strength.
Milan Kracalik | Montanuniversitaet Leoben | Austria
9:00 – 9:30
Invariance of Elongational Viscosity Measurements Using SER Universal Testing Platform with Respect to Rectangular Shapes of Polymer Samples
Autors:
P. Filip and P. Svrcinova
Affiliation:
Institute of Hydrodynamics, Acad.Sci.Czech Rep. Pod Patankou 5, 166 12 Prague 6, Czech Republic.
Abstract:
The aim of this contribution is to present invariance of elongational viscosity measured with respect to a rectangular shape and thickness of LDPE samples using an SER Universal Testing Platform fixed in Anton Paar MCR 501 host system. The width of the samples was changed in the range 2.1-12.7 mm and thickness altered within 0.3÷1 mm. The measurements when a thickness attained 0.1 mm are also presented. There are further compared measurements with and without the clamps.
Keywords: Elongational viscosity; SER Universal Testing Platform; Polymer melts.
Petr Filip | Institute of Hydrodynamics ASCR | Czech Republic
9:30 – 10:30
Cofee break & Poster section & Exhibition
On the Approximation of the Generalised Stretch Function
Autors:
A. A. Kharlamov and P. Filip
Affiliation:
Institute of Hydrodynamics, Acad.Sci.Czech Rep., Pod Patankou 5, 166 12 Prague 6, Czech Republic.
Abstract:
The integral 
over full solid angle expresses a ratio of the lengths of a random walk molecule in deformed and undeformed state. The aim of this contribution is to study a generalised form of this integral 
, for which the special cases are met in several constitutive models describing behaviour of polymeric materials. For determining the integral there was found a recurrence equation providing a solution for any real p. There was found an asymptotic solution for the recurrence equation, p>>0, which provides a basis for the approximations of the integral for 
.
Keywords: Polymers, Molecule Length, Stretch Function, Recurrence Equation, Finger Tensor, Cauchy Tensor.
Alexander Kharlamov | Institute of Hydrodynamics ASCR | Czech Republic
Investigation of Vortex Development During Polymer Melt Flows by Flow Birefringence
Autors:
Jan Musil 1, 2), Martin Zatloukal 1, 2), Tim Gough 3) and Mike Martyn 3)
Affiliations:
1) Centre of Polymer Systems, Tomas Bata University in Zlín, nám. T. G. Masaryka 5555, 760 01 Zlín, Czech Republic.
2) Polymer Centre, Faculty of Technology, Tomas Bata University in Zlín, nám. T. G. Masaryka 275, 762 72 Zlín, Czech Republic.
3) IRC in Polymer Engineering, School of Engineering, Design and Technology, University of Bradford, Richmond Road, BD7 1DP, Bradford, United Kingdom.
Abstract:
The vortex development of low-density polyethylene Lupolen 1840H polymer melt under various processing conditions has been investigated by flow induced stress birefringence technique. It has been revealed that effect of mass flow rate and temperature on the vortex size has non-monotonic character, which is in good agreement with laser-doppler velocimetry based measurements reported for the same polymer in the open literature. This suggests that the flow induced stress birefringence technique can be considered as the quick and reasonably precise tool for vortices shape/size visualization and quantification at the slit die entry region.
Keywords: Vortex formation, Secondary flows, Flow instabilities, Flow birefringence, Planar extensional viscosity, Extrusion.
Jan Musi | Tomas Bata University in Zlin | Czech Republic
On Pressure Affected Shear Viscosity of Poly(Lactic) Acid
Autors:
Pongprapat Piyamanocha, Tomas Sedlacek, and Petr Saha
Affiliation:
Centre of Polymer System, Polymer Centre, Tomas Bata University in Zlín,, nám T.G.Masaryka 5555, 760 01 Zlín, Czech Republic.
Abstract:
Evaluation of pressure coefficient of polymer melt viscosity has become important parameter taken into account for flow behavior prediction in polymer processing simulation software. In this paper, the pressure coefficient of biodegradable polymers, poly(lactic) acid (PLA), was investigated. A capillary rheometer equipped with back pressure device controlling pressure in polymer melt during flow was employed for experiments. Pressure sensitivity was evaluated through pressure coefficient calculated via fitting of obtained viscosity data by the help of Carreau-Yasuda model. It was found that pressure coefficient of PLAs is strongly affected by the internal structure of tested polymer.
Keywords: Pressure dependent viscosity, Rheology, Poly(lactic) acid.
Pongprapat Piyamanocha | Tomas Bata University in Zlin | Czech Republic
Partial Restoring of Thermorheological Simplicity and Terminal Dynamics Behavior of PEO/PMMA in the Presence of Nanoparticles
Autors:
Hossein Ali Khonakdar 1, 4), Mahdi Ghelichi 2), Nader Taheri Qazvini 3), Seyed Hassan Jafari 2) and Udo. Wagenknecht 4)
Affiliations:
1) Iran Polymer and Petrochemical Institute, P.O. Box 14965-115, Tehran, Iran.
2) School of Chemical Engineering, University of Tehran, P.O. Box 11155-4563, Tehran, Iran.
3) School of Chemistry, College of Science, University of Tehran, P.O. Box 14155-6455, Tehran, Iran.
4) Leibniz Institute of Polymer Research Dresden, Hohe Str. 6, D-01069, Dresden, Germany.
Abstract:
The influence of nanoparticles on the terminal dynamics and thermorheology of miscible PEO/PMMA is studied through rheology. It is found that the dynamics of the components would be highly altered in the presence of nanoparticles, sodium montmorillonite. The dynamics of PEO is retarded due to its absorbance to the surface of the nanoparticles. However, the dynamics of PMMA is seen to be accelerated because of the compatibilizing effect of nanoparticles via introducing favorable interactions. Failure of time-temperature superposition (TTS) was apparent in the case of neat blend, whereas addition of nanoparticles resulted in partial restoring the TTS.
Keywords: Polymer blends, Terminal dynamics, Thermorheological properties, Nanocomposites.
Hossein Ali Khonakdar | Leibniz Institute of Polymer Research Dresden | Germany
Stress-strain hysteresis of a carbon nanotube network as polymer nanocomposite filler under cyclic deformation
Autors:
P. Slobodian and P Saha
Affiliation:
Centre of Polymer Systems, Faculty of Technology, Tomas Bata University in Zlín, nám. T.G.Masaryka 555, 760 05 Zlín, Czech Republic.
Abstract:
A network of entangled multiwall carbon nanotubes is an assembly of non-bonded and randomly oriented units whose mechanical behavior is affected by their buckling, compression and slippage at contact points. Slippage and irreversible nanotube rearrangements are evidenced by the hysteresis in the stress-strain curves during loading and unloading cycles. To model the mechanical behavior, a nonlinear rheological model is proposed as a combination of the elastic and the friction stresses and a kinetic equation.
Keywords: Carbon nanotubes, Entangled network, Mechanical properties, Cyclic deformation.
Petr Slobodian | Tomas Bata University in Zlin | Czech Republic
Effect of fluoropolymer antidripping agent on rheological behavior of LLDPE
Autors:
Aleš Obr 1) and Martin Zatloukal 2, 3)
Affiliations:
1) SILON s.r.o, Planá nad Lužnicí, Průmyslová 451, Czech Republic.
2) Polymer Centre, Faculty of Technology, Tomas Bata University in Zlín, nám. T. G. Masaryka 275, 762 72 Zlín, Czech Republic.
3) Centre of Polymer Systems, Tomas Bata University in Zlín, nám. T. G. Masaryka 5555, 760 01 Zlín, Czech Republic.
Abstract:
In this work, high molecular weight polytetrafluoroethylene based antidripping agent was blended with Ziegler-Natta based LLDPE in different concentrations. Rheological characterization was consequently performed for all the blends and the obtained results were compared with the pure LLDPE. It has been found that high molecular weight PTFE based melt modifier MM 5935 EF significantly enhancing the shear viscosity/elasticity and especially the extensional viscosity of the LLDPE melt.
Keywords: Fluoropolymer, antidripping, polymer melts, rheological properties.
Aleš Obr | SILON s.r.o. | Czech Republic
Effect of Strain on Viscoelastic Behavior of PVP-CMC Based Medicated Hydrogels
Autors:
Niladri Roy 1, 2), Nabanita Saha 1, 2), Takeshi Kitano 1, 2) and Petr Saha 1, 2)
Affiliations:
1) Polymer Centre, Faculty of Technology, Tomas Bata University in Zlin, T.G.Masaryka-275, 76272, Zlin, Czech Republic.
2) Centre of Polymer Systems, Tomas Bata University in Zlín, nám. T.G.Masaryka-5555, 760 01 Zlín, Czech Republic.
Abstract:
PVP-CMC and PVP-CMC-BA are designated as medicated hydrogels which are elastic in nature like other gels and solids. This present work was focused on the effect of strain on viscoelastic behavior of these medicated hydrogels. Dynamic frequency sweep test at 10% strain and dynamic strain sweep tests at different angular frequencies were performed on these hydrogels. Freshly prepared hydrogels and hydrogels swelled for 60 min from dry state were chosen for the experiments. These two experiments reveal that both PVP-CMC and PVP-CMC-BA hydrogels (fresh and swelled) maintain elastic behavior from very low to medium strain, but at high strain they become viscous in nature.
Keywords: Hydrogels, frequency, strain, swelling, viscoelastic.
Niladri Roy | Tomas Bata University in Zlin | Czech Republic
Viscoelastic Properties and Morphology of Mumio-based Medicated Hydrogels
Autors:
Oyunchimeg Zandraa 1), Lenka Jelínková 2), Niladri Roy 2), Tomáš Sáha 1), Takeshi Kitano 2) and Nabanita Saha 2)
Affiliations:
1) Medical Materials Research Centre, University Institute, Tomas Bata University in Zlín, Nad Ovčírnou 3685, 760 01 Zlín, Czech Republic.
2) Centre of Polymer Systems, Polymer Centre, Faculty of Technology, Tomas Bata University in Zlín, TGM 5555, 760 01 Zlín, Czech Republic.
Abstract:
Novel medicated hydrogels were prepared (by moist heat treatment) with PVA, agar, mumio, mare´s milk (MM), seabuckthorn oil (SB oil) and salicylic acid (SA) for wound dressing / healing application. Scanning electron micrographs (SEM) show highly porous structure of these hydrogels. The swelling behaviour of the hydrogels in physiological solution displays remarkable liquid absorption property. The knowledge obtained from rheological investigations of these systems may be highly useful for the characterization of the newly developed topical formulations. In the present study, an oscillation frequency sweep test was used for the evaluation of storage modulus (G´), loss modulus (G´´), and complex viscosity (η*) of five different formulations, over an angular frequency range from 0.1 to 100 rad/s. The influence of healing agents and swelling effect on the rheological properties of mumio-based medicated hydrogels was investigated to judge its application on uneven surface of body.
Keywords: Medicated hydrogel, Polyvinyl alcohol, Agar, Mumio, Swelling, Viscoelasticity, Morphology.
Lenka Jelinkova | Tomas Bata University in Zlin | Czech Republic
Electrorheological Properties of Suspensions of Polypyrrole Ribbon Particles in Silicone Oil
Autors:
Shawqi Almajdalawi, Vladimir Pavlinek, Qilin Cheng, Petr Saha, Miroslav Mrlik and Martin Stenicka
Affiliation:
Centre of Polymer Systems, Faculty of Technology, Tomas Bata University in Zlín, nám. T.G.Masaryka 5555, 760 01 Zlín, Czech Republic.
Abstract:
Anew polypyrrole (PPy) ribbon particles structure has been synthesized by solution chemistry method (oxidative polymerization) in the presence of surfactant cetyltrimethylammonium bromide (CTAB) with oxidizing agent ammonium persulfate (APS). The resulted polymer was treated with ammonium hydroxide (NH4OH) several times to obtain different sample conductivity. PPy morphology was characterized by SEM. The suspensions were prepared by dispersing PPy with different conductivities in silicone oil. The electrorheological effect (ER) for the suspensions was examined under various electric fields using a rotational rheometer. It was found that suspension of only 3 wt.% of PPy ribbon particles showed large ER effect providing yield stress of 256 Pa at 3 kV/mm.
Keywords: Polypyrrole ribbon particles, Electrorheology, Conductivity.
Shawqi Almajdalawi | Tomas Bata University in Zlin | Czech Republic
Core-shell Structured Polypyrrole-coated Magnetic Carbonyl Iron Microparticles and their Magnetorheology
Autors:
Michal Sedlacik 1), Vladimir Pavlinek 1), Petr Saha 1), Petra Svrcinova 2) and Petr Filip 2)
Affiliations:
1) Centre of Polymer Systems, Faculty of Technology, Tomas Bata University in Zlín, nám. T.G.Masaryka 5555, 760 01 Zlín, Czech Republic.
2) Institute of Hydrodynamics, Academy of Sciences of the Czech Republic, Pod Patankou 5, 166 12 Prague 6, Czech Republic.
Abstract:
The substantial sedimentation problem of magnetorheological (MR) suspensions, due to the large density mismatch between dispersed particles and carrier medium, is a significant obstacle for their broader applications. The present paper reports the MR properties and enhanced sedimentation stability of novel core-shell structured particles with carbonyl iron as a core and polypyrrole as a shell layer dispersed in silicone oil. The coating morphology was analyzed via scanning electron microscopy and magnetic properties via vibrating sample magnetometry. The steady shear flow and small-amplitude dynamic oscillatory shear measurements were carried out to show improved MR performance. The sedimentation test showed positive role of polymeric coating, as well.
Keywords: Carbonyl iron, Core-shell, Magnetorheological suspension, Polypyrrole, Sedimentation, Viscoelasticity.
Michal Sedlacik | Tomas Bata University in Zlin | Czech Republic
Linear elastic behaviour of complex polyurethane foams
Autors:
Bart Buffel 1), Ignace Verpoest 2), Frederik Desplentere 1) and Maarten Moesen 2)
Affiliations:
1) Polymer processing division, Department of Mechanical engineering, Faculty of Industrial Engineering Sciences and technology, KHBO University College, Zeedijk 101, 8400 Oostende Belgium.
2) Composite Materials Group, Metallurgy and Materials Engineering department, Catholic University Leuven, Kasteelpark Arenberg 44, 3001 Leuven, Belgium.
Abstract:
Recently the Belgian company Recticel S.A. has developed a new composite material in which two different types of polyurethane foam – a open cell flexible foam and a closed cell rigid foam- are used. Both of these foams are produced in-house and a new production process was designed to combine these foams into one material known by its brand name “Compolite®”. This material will serve as core material in sandwich structures with complex 3D shapes.
The current research investigates the linear elastic behavior of the complex foam. A full factorial design of experiments was used to determine the mechanical properties of the complex foam and its constituents by means of compressive experiments. The results clearly show that foam density has a major impact on the mechanical properties as opposed to the cell size of the open cell foam. A significant difference in stiffness between the complex foam and the rigid closed cell foam was observed.
Using the commercial,l UGS NX 7.5 Finite Element software attempts are made to explain this difference. At first a classical simplification of cellular material into 2D honeycombs has been made followed by a more elaborate 3D model based on the Kelvin cell geometry.
Keywords: polyurethane foam, Kelvin Cell, foam mechanics.
Frederik Desplentere | KHBO University College | Belgium
The effect of PVAc solution viscosity on diameter of PVAc nanofibres prepared by technology of electrospinning
Autors:
David Petras 1, 2), Petr Slobodian 1), Vladimír Pavlínek 1), Petr Sáha 1) and Dušan Kimmer 2)
Affiliations:
1) Centre of Polymer Systems, Faculty of Technology, Tomas Bata University in Zlín, nám. T.G.Masaryka 555, 760 05 Zlín.
2) SPUR a.s., Tr. Tomase Bati 299, 763 02 Zlin, Czech Republic.
Abstract:
Polyvinyl acetate (PVAc) nanofibers were prepared by technology of electrospinning with help of multi-jets electrospinning machine from acetic acid/water solvent system. The stability of the process was tested in a broad concentration region from 5 to 40 wt. % of PVAc. The main attention was carried out to study the effect of polyvinyl acetate solution concentration/viscosity onto mean diameter of prepared nanofibers. It was found that increased solution viscosity leads to increase of fibers diameters from appox. 60 nm at viscosity ~ 0.04 Pa.s to appox. 1000 nm at viscosity ~ 6-7 Pa.s. The PVAc nanofibres can be considered as a potential precursor for preparation of inorganic fibrous nanoparticles. Their dimensions can be effectively controlled by PVAc nanofibers diameter by easy diameter – concentration/viscosity optimalization.
Keywords: Polyvinyl acetate, PVAc, nanofibers, nanofiber layer, electrospinning, acetic acid, water.
Vladimir Pavlinek | Tomas Bata University in Zlin | Czech Republic
INTRODUCTION OF NOVEL RHEOLOGICAL TOOLS
(Chairman: Zdenek Stary)
10:30 – 11:00
Analystical Instrumentation for Malvern Instruments to Analyse Polymer Samples
Torsten Remmler | Malvern Instruments GmbH | Germany
11:00 – 11:30
Advances in Small Scale Processing Equipment for Polymers and Additives
Autor:
Bernd Jakob
Affiliation:
Thermo Fisher Scientific, Karlsruhe, Germany.
Abstract:
The use of a conical twin screw extruder with backflow channel combines aspects of mixing and extrusion in a batch process. With a small force feeder and a conveyor belt the micro compounder operates continuously producing a strand or a small sheet. With a total filling volume of 7 ml and a built in slit capillary die the applications focus ison compounding and reactions of small amounts of polymers in molten stage. Two great areas of application: mixing and rheological recording of melt characteristics are combined in the micro compounder. For further tests the polymer melt can be transferred into a micro injection moulding machine to shape different kind of test specimens for further analyses.
Bernd Jakob | Thermo Fisher Scientific | Germany
11:30 – 13:00
Lunch & Exhibition
NON-NEWTONIAN FLUID MECHANICS
(Chairman: Jiri Vlcek)
13:00 – 13:30
Modelling of Polymer Flows by Lattice-Boltzmann Method
Autor:
Alexander Vikhansky
Affiliation:
School of Engineering and Materials Science, Queen Mary, University of London, Mile End Road, London E1 4NS, UK.
Abstract:
A novel generalized Newtonian model has been implemented in a lattice-Boltzmann (LB) algorithm. Viscosity is given as a function of the principal invariants of the deformation rate tensor. The collision term of the LB method is linked to the second moment of the velocity distribution via a non-linear algebraic equation. It is shown that this equation can be efficiently solved for an arbitrary rheological law.
Keywords: Lattice-Boltzmann method, Non-Newtonian fluids.
Alexander Vikhansky | University of London | UK
13:30 – 14:00
Variational Principle Based Stability Analysis of Non-Isothermal Film Blowing Process for Non-Newtonian Fluids
Autors:
Roman Kolarik 1, 2) and Martin Zatloukal 1, 2)
Affiliations:
1) Centre of Polymer Systems, Tomas Bata University in Zlín, nám. T. G. Masaryka 5555, 760 01 Zlín, Czech Republic.
2) Polymer Centre, Faculty of Technology, Tomas Bata University in Zlín, nám. T. G. Masaryka 275, 762 72 Zlín, Czech Republic.
Abstract:
In this work, a stable numerical scheme for the film blowing stability analysis, considering the variational principle based film blowing model, non-isothermal processing conditions and non-Newtonian behavior of the polymer, has been proposed and used with the aim to reveal the effect of flow activation energy, heat transfer coefficient, mass flow rate and melt temperature on the film blowing stability. It has been found that the model predictions are in good agreement with the corresponding experimental data taken from the open literature.
Keywords: Blown film stability, non-isothermal process, non-Newtonian fluids, polymer processing modeling.
Roman Kolarik | Tomas Bata University in Zlin | Czech Republic
14:00 – 14:30
Flow of Viscoelastic Polymer Solutions through Filter Screens
Autors:
Ivan Machač, Alexander Surý and Bedřich Šiška
Affiliation:
University of Pardubice, Institute of Environmental and Chemical Engineering, Studentská 573, 532 10 Pardubice, Czech Republic.
Abstract:
In this contribution, the measurements are presented of the pressure drop in the creeping flow of viscoelastic solution of polyacrylamides through metal wire screens, differing in wire diameter, aperture dimension, and type of weaving,. In this flow, a strong elastic pressure drop excess manifest itself. Analysing the extensive set of experimental data, it was verified that for engineering estimation of the pressure drop excess, a simple form of the corrective Deborah number function can be used.
Keywords: Flow through filter screens; Viscoelastic fluids; Pressure drop excess, Deborah number function.
Ivan Machac | University of Pardubice | Czech Republic
14:30 – 15:00
Refreshment & Exhibition
APPLIED RHEOLOGY FOR POLYMER NANOFIBERS
(Chairman: Martin Zatloukal)
15:00 – 15:30
Morphology of Nano and Micro Fiber Structures in Ultrafine Particles Filtration
Autors:
Dusan Kimmer 1), Ivo Vincent 1), Jan Fenyk 1), David Petras 1), Martin Zatloukal 2), Wannes Sambaer 2) and Vladimir Zdimal 3)
Affiliations:
1) SPUR a.s., T. Bati 299, 764 22 Zlín, Czech Republic.
2) Centre of Polymer Systems, Tomas Bata University in Zlín, nám. T. G. Masaryka 5555, 760 01 Zlín, Czech Republic.
3) Institute of Chemical Process Fundamentals of the AS CR, v.v.i., Rozvojova 135, 165 02 Praha 6, Czech Republic.
Abstract:
Selected procedures permitting to prepare homogeneous nanofibre structures of the desired morphology by employing a suitable combination of variables during the electrospinning process are presented. A comparison (at the same pressure drop) was made of filtration capabilities of planar polyurethane nanostructures formed exclusively by nanofibres, space polycarbonate nanostructures having bead spacers, structures formed by a combination of polymethyl methacrylate micro- and nanofibres and polypropylene meltblown microstructures, through which ultrafine particles of ammonium sulphate 20 – 400 nm in size were filtered. The structures studied were described using a new digital image analysis technique based on black and white images obtained by scanning electron microscopy. More voluminous structures modified with distance microspheres and having a greater thickness and mass per square area of the material, i.e. structures possessing better mechanical properties, demanded so much in nanostructures, enable preparation of filters having approximately the same free volume fraction as flat nanofibre filters but an increased effective fibre surface area, changed pore size morphology and, consequently, a higher filter quality.
Keywords: Morphology optimization, nanofiber, beaded nanofiber, bead defects, bead formations, bead spacers, electrospinning, nanolayers homogeneity, filtration efficiency, 3D nanostructure characterization.
Dusan Kimmer | SPUR a.s. | Czech Republic
15:30 – 16:00
3D Air Filtration Modeling for Nanofiber Based Filters in the Ultrafine Particle Size Range
Autors:
Wannes Sambaer 1, 2), Martin Zatloukal 1, 2) and Dusan Kimmer 3)
Affiliations:
1) Centre of Polymer Systems, Tomas Bata University in Zlín, nám. T. G. Masaryka 5555, 760 01 Zlín, Czech Republic.
2) Polymer Centre, Faculty of Technology, Tomas Bata University in Zlín, nám. T. G. Masaryka 275, 762 72 Zlín, Czech Republic.
3) SPUR a.s., T. Bati 299, 764 22 Zlin, Czech Republic.
Abstract:
In this work, novel 3D filtration model for nanofiber based filters has been proposed and tested. For the model validation purposes, filtration efficiency characteristics of two different polyurethane nanofiber based structures (prepared by the electrospinning process) were determined experimentally in the ultrafine particle size range (20-400 nm). It has been found that the proposed model is able to reasonably predict the measured filtration efficiency curves for both tested samples.
Keywords: Nanofiber, Electrospinning, 3D Simulation, Filtration Modelling.
Wannes Sambaer | Tomas Bata University in Zlin | Czech Republic
16:00
End of the conference