* The abstracts are available for each conference contribution when you click on the corresponding title.
July 30, 2013
7:00 – 8:20
Registration
8:20 – 8:30
Welcome
SLIP OF POLYMER MELTS
(Chairman: A. Jeffrey Giacomin)
8:30 – 9:10
Plenary lecture
Wall Slip of Linear Polymers (HDPEs)
Autors:
Mahmoud Ansari and Savvas G. Hatzikiriakos
Affiliation:
Department of Chemical and Biological Engineering, The University of British Columbia, Vancouver, BC, Canada.
Abstract:
The slip behavior of several high-density polyethylenes (HDPEs) is studied as a function of molecular weight (Mw) and its distribution for moderate to broad molecular weight distribution resins. It is found that slip depends strongly on Mw and its distribution. The slip velocity increases with decrease of molecular weight, which is expected to decay to zero as the Mw approaches a value with characteristic molecular dimension similar to surface asperities. For HDPEs that exhibit stick-slip transition, the slip velocity (before the stick-slip) has been found to increase with increase of polydispersity. The strong slip observed above the stick-slip flow regime is found to be independent of the molecular weight characteristics. A criterion is also discussed as to the occurrence or not of the stick-slip transition which is found to depend strongly on Mw and its distribution.
Keywords: Wall slip, Stick-slip transition, Flow instabilities, Mooney analysis, High-density polyethylenes, Broad molecular weight distribution.
Savvas Hatzikiriakos | The University of British Columbia | Canada
9:10 – 9:40
Microfluidics Study of the Effect of Polydispersity on Interfacial Slip of Polymer Melts
Autors:
Seyed M. Sabzevari and Paula M. Wood-Adams
Affiliation:
Department of Mechanical and Industrial Engineering, Concordia University Montreal, QC, Canada.
Abstract:
We have characterized the effect of molecular weight distribution on interfacial slip of polymers in simple planar Couette flow using tracer particle velocimetry and confocal microscopy. The experiments provide direct measurements of the velocity profile of over a wide range of shear rates allowing for the determination of slip velocity, slip length and critical shear rate for the onset of strong slip. Polydisperse samples of polybutadiene with a fixed weight-average molecular weight, Mw, and varying number-average molecular weight, Mn, and vice versa, as well as samples with fixed Mw and Mn but varying composition were produced from nearly-monodisperse samples (Mw/Mn < 1.11 with molecular weights ranging from 3 kg.mol-1 to 100 kg.mol-1). The results showed that the slip behavior is significantly affected by the molecular weight distribution of the polymer when Mn is dropped below a critical value at a fixed Mw. A novel relationship for the slip of polydisperse polymers is proposed by generalizing the Brochard-de Gennes slip theory for monodisperse linear polymers on semi-ideal surfaces.
Keywords: Interfacial slip, Microfluidcs.
Paula M. Wood-Adams | Concordia University Montreal | Canada
9:40 – 10:10
Cofee break & Exhibition
ELONGATIONAL RHEOLOGY OF POLYMER MELTS I
(Chairman: Manfred H. Wagner)
10:10 – 10:50
Plenary lecture
Elongational Experiments on Polymer Melts and Their Assessment
Autor:
Helmut Münstedt
Affiliation:
Institute of Polymer Material, Friedrich-Alexander University Erlangen-Nürnberg, Martensstr. 7, D-91058 Erlangen, Germany.
Abstract:
Regarding the literature, steady-state values of the elongational viscosity are not widely documented and it is still an open question, whether the time-dependent elongational viscosity of strain-hardening polymeric materials runs through a maximum as a function of time before it reaches its steady state. For the assessment of molecular theories reliable experimental data are essential, however. From a survey of extensional experiments at constant elongational rates it becomes very probable that an extended stationary state of elongational exists and that maxima of the tensile stresses or even overshoot phenomena are due to non-uniform deformations of the samples. This conclusion is supported by creep experiments for which a steady state is reached at comparatively smaller total elongations corresponding to a better uniformity.
Keywords: Polymer melts, Extensional rheology, Experimental devices, Steady-state elongational viscosity, Theories, Uniformity of deformation.
Helmut Münstedt | Friedrich-Alexander University Erlangen-Nürnberg | Germany
10:50 – 11:20
On the Viscosity Maximum during Uniaxial Extension: Material Property or Measuring Artifact?
Autors:
Zdeněk Starý 1), Teodor Burghelea 2) and Helmut Münstedt 1)
Affiliations:
1) Institute of Polymer Materials, Friedrich-Alexander-University Erlangen-Nuremberg, Martensstr. 7, D-91058 Erlangen, Germany.
2) Laboratoire de Thermocinétique, Ecole Polytechnique Nantes, La Chantrerie, Rue Christian Pauc BP 50609, 44 306 NANTES, France.
Abstract:
An experimental investigation of the viscosity maximum observed during uniaxial extension of a low density polyethylene is presented. For this purpose, traditional integral viscosity measurements on a Münstedt-type extensional rheometer are combined with local measurements based on the in-situ visualization of the sample under extension. For elongational experiments at intermediate constant strain rates local maximum of the extensional viscosity is systematically observed. Images of samples within this regime show that secondary necks develop along the sample at the moment when the maximum of the integral viscosity is observed. The emergence of a maximum of the integral elongational viscosity is, thus, related to the distinct non-uniformity of deformation states and most probably not to the rheological properties of the material. Moreover, the position of the viscosity maximum was found to be dependent on the initial geometry of the specimen. This indicates again that the appearance of the transient viscosity maximum is not a material property but an artifact caused by a geometrical non-uniformity of highly stretched specimens.
Keywords: Polymer melts, Rheology, Elongational flow.
Zdeněk Starý | Friedrich-Alexander University Erlangen-Nürnberg | Germany
11:20 – 11:50
True Ultra-high Strain Constant Rate and Stress Uniaxial Extensional Rheometry
Autors:
Ricardo J. Andrade and Joao M. Maia
Affiliation:
Department of Macromolecular Science & Engineering, Case Western Reserve University, 2100 Adelbert Rd., Cleveland, OH 44106, USA.
Abstract:
Usually, when studies on uniaxial extension of polymer melts are performed, the main concern is the achievement of the largest possible deformation with a homogeneous stretching of the sample at the highest deformation rate possible. Therefore, it is necessary to ensure that the correct experimental conditions are achieved, which, more often than not, is not the case. In fact, despite a wealth of work available in the open literature that highlights the importance of correctness of the experimental method, many researchers still disregard basic experimental phenomena such as, for example, the almost certain discrepancy between the nominal and the true strain rates being imposed on the sample, poor sample preparation, inadequate sample dimensions and the effects of sagging in fiber wind-up, e.g., SER, and Meissner-type devices. In this work we build on previous works by our group and use our new CSER, a dual Controlled-Stress/rate Extensional Rheometer, to highlight the importance of truly controlling the strain rate in rate-controlled experiments and the tensile stress in tensile creep, which can only be achieved via visually accessing the sample during deformation and using a feedback control loop to keep the desired parameter constant. In the former case we will show that by using the control loop to compensate for the deviations in the expected cross-section evolution over time it is possible to minimize or even eliminate the planar component of the deformation known to be present when relatively wide samples are used, e.g., to prevent sagging in SER-type devices. In the latter case we show that imposing a simple exponentially decreasing torque on the sample masks important transient effects and that these are only picked up when the tensile stress being applied is truly kept constant via the application of said real-time feedback control loop.
Keywords: Extensional rheometry.
Joao M. Maia | Case Western Reserve University | USA
11:50 – 12:20
Evaluation of Temperature-strain rate Dependent Uniaxial and Planar Elongational Viscosities for Branched LDPE Polymer Melt
Autor:
Martin Zatloukal 1, 2)
Affiliations:
1) Polymer Centre, Faculty of Technology, Tomas Bata University in Zlin, nam. T. G. Masaryka 275, 762 72 Zlin, Czech Republic.
2) Centre of Polymer Systems, University Institute, Tomas Bata University in Zlin, Nad Ovcirnou 3685, 760 01 Zlin, Czech Republic.
Abstract:
In this work, novel rectangle and circular orifice dies have been utilized for temperature-strain rate dependent planar and uniaxial elongational viscosity measurements for the LDPE polymer melt by using standard twin bore capillary rheometer and Cogswell model and the capability of three different constitutive equations (novel generalized Newtonian model, modified White-Metzner model, modified Leonov model) to describe the measured experimental data has been tested. It has been shown that chain branching causes the strain hardening occurrence in both, unixial and planar elongational viscosities and its maximum is shifted to the higher strain rates if the temperature is increased. The level of uniaxial elongational strain hardening for the branched LDPE sample has been found to be higher in comparison with the planar elongational viscosity within wide range of temperatures.
Keywords: Orifice die, Planar elongational viscosity, Uniaxial elongational viscosity, Cogswell model, Entrance pressure drop, Polymer melts, Capillary rheometer, Constitutive equations.
Martin Zatloukal | Tomas Bata University in Zlin | Czech Republic
12:20 – 13:50
Lunch & Exhibition
EXTRUSION FLOW MODELING
(Chairman: Frederik Desplentere)
13:50 – 14:20
Effect of Polymer Melt Wall Slip on the Flow Balance of Profile Extrusion Dies
Autors:
Olga S. Carneiro, Luís L. Ferrás, Fernando T. Pinho, João M. Nóbrega
Affiliation:
IPC/I3N-Institute Polymers and Composites, Department of Polymer Engineering University of Minho, Campus de Azurém, 4800-058 Guimarães, Portugal
Abstract:
This work describes the implementation of the wall slip boundary condition in an in-house developed 3D numerical code based on the Finite Volume Method. For this purpose, several phenomenological models relating the velocity and the shear stress at the wall were implemented. This new feature is verified using a simple case study, by comparing the numerical results with those obtained through the corresponding analytical solution. Then, the potentialities of the new code are illustrated performing flow simulations of a polymer melt in a complex flow channel. The results obtained show that the slip at the wall influences the flow distribution at the die flow channel outlet. Therefore, and to assess the relevance of slippage in the optimal die geometry, the automatic optimization of a die flow channel, required for the production of a specific thermoplastic profile, is performed using both the no-slip and slip boundary conditions, together with two alternative optimization strategies. It is shown that slip favors the flow balance of the dies and also other issues of its performance.
Keywords: Wall slip, Flow balance, Extrusion die design.
Olga S. Carneiro | University of Minho | Portugal
14:20 – 14:50
On the Performance of a 2D Unstructured Computational Rheology Code on a GPU
Autors:
Simão P. Pereira 1), Kees Vuik 2), Fernando T. Pinho 3) and João M. Nóbrega 1)
Affiliations:
1) I3N-Institute for Polymers and Composites, University of Minho, Campus Azurém, Guimarães 4800-058, Portugal.
2) Delft University of Technology, Faculty of Electrical Engineering, Mathematics and Computer Science, Department of Applied Mathematics, Mekelweg 4, 2628 CD, Delft, The Netherlands.
3) CEFT, Faculdade de Engenharia da Universidade do Porto, Rua Dr. Roberto Frias, s/n, 4200-465 Porto, Portugal.
Abstract:
The present work explores the massively parallel capabilities of the most advanced architecture of graphics processing units (GPUs) code named “Fermi”, on a two-dimensional unstructured cell-centred finite volume code. We use the SIMPLE algorithm to solve the continuity and momentum equations that was fully ported to the GPU. The benefits of this implementation are compared with a serial implementation that traditionally runs on the central processing unit (CPU). The developed codes were assessed with the bench-mark problems of Poiseuille flow, for Newtonian and generalized Newtonian fluids, as well as by the lid-driven cavity and the sudden expansion flows for Newtonian fluids. The parallel (GPU) code accelerated the resolution of those three problems by factors of 19, 10 and 11, respectively, in comparison with the corresponding CPU single core counterpart. The results are a clear indication that GPUs are and will be useful in the field of computational fluid dynamics (CFD) for rheologically simple and complex fluids.
Keywords: Graphics processing units, Computational fluid dynamics, Parallelization, Finite volume method, Unstructured meshes.
João M. Nóbrega | University of Minho | Portugal
14:50 – 15:20
Cofee break & Exhibition
NANOCOMPOSITES AND POLYMER BLENDS
(Chairman: Zdeněk Starý)
15:20 – 15:50
Rheology as a Tool to Follow Hybrid Nanocomposites Preparation
Autors:
Manuel Oliveira and Ana Vera Machado
Affiliation:
IPC –Institute for Polymers and Composites/I3N, Department of Polymer Engineering, University of Minho, 4800-058 Guimarães, Portugal.
Abstract:
Hybrid nanocomposites were prepared using two polymeric matrices and the one inorganic precursor. Rheological measurements were performed in order to characterize and follow the reactions and to assess the effect of temperature and time on the nanocomposite structure. The experimental results evidenced that crosslinking occurs for both polymers. Higher crosslinking density and well dispersed nanoparticles morphology were achieved with EVA.
Keywords: Rheology, Sol-gel reactions, Hybrid polymers nanocomposites.
Ana Vera Machado | University of Minho | Portugal
15:50 – 16:20
Description of the Flow Induced Coalescence in Immiscible Polymer Blends – Advances and Persisting Problems
Autors:
Ivan Fortelný and Josef Jůza
Affiliation:
Institute of Macromolecular Chemistry AS CR, Heyrovsky Sq. 2, 162 06 Prague 6, Czech Republic.
Abstract:
The contribution discusses present state of art of modeling of the flow induced coalescence with respect to applicability of its results to the control of the phase structure evolution in flowing polymer blends. It is shown that the theory based on the switch between equations for matrix drainage between spherical or highly flattened droplets provides for probability, Pc, that the collision of droplets will be followed by their fusion, similar dependences on system parameters as more complicated modeling. This theory facilitates to consider the effect of the matrix elasticity on coalescence. Pc decreases with the matrix relaxation time. This decrease is small for short relaxation times but pronounced for long relaxation times. A new equation for description of the matrix drainage between flattened droplets is proposed, which is applicable for the whole range of viscosity ratios of the droplets and matrixes. Comparison of the assumptions of available theories of coalescence with characteristics of real polymer blends lead us to the conclusion that the effects of the elasticity and anisometry of droplets and their interactions in concentrated systems on coalescence need further intensive investigation. Finding of proper method of description of the coalescence in complex flow fields is needed for reliable prediction of the phase structure evolution during mixing and processing of polymer blends.
Keywords: Coalescence, Polymer blends, Matrix drainage, Viscoelasticity, Droplet deformation.
Ivan Fortelný | Institute of Macromolecular Chemistry ASCR | Czech Republic
18:30
Conference dinner
July 31, 2013
ELONGATIONAL RHEOLOGY OF POLYMER MELTS II
(Chairman: Helmut Münstedt)
8:00 – 8:40
Plenary lecture
Elongational Flow of Polymer Melts at Constant Strain Rate, Constant Stress and Constant Force
Autors:
Manfred H. Wagner and Víctor H. Rolón-Garrido
Affiliation:
Chair of Polymer Engineering/Polymer Physics, Berlin Institute of Technology (TU Berlin), Fasanenstrasse 90, D-10623 Berlin, Germany.
Abstract:
Characterization of polymer melts in elongational flow is typically performed at constant elongational rate or rarely at constant tensile stress conditions. One of the disadvantages of these deformation modes is that they are hampered by the onset of “necking” instabilities according to the Considère criterion. Experiments at constant tensile force have been performed even more rarely, in spite of the fact that this deformation mode is free from necking instabilities and is of considerable industrial relevance as it is the correct analogue of steady fiber spinning. It is the objective of the present contribution to present for the first time a full experimental characterization of a long-chain branched polyethylene melt in elongational flow. Experiments were performed at constant elongation rate, constant tensile stress and constant tensile force by use of a Sentmanat Extensional Rheometer (SER) in combination with an Anton Paar MCR301 rotational rheometer. The accessible experimental window and experimental limitations are discussed. The experimental data are modelled by using the Wagner I model. Predictions of the steady-start elongational viscosity in constant strain rate and creep experiments are found to be identical, albeit only by extrapolation of the experimental data to Hencky strains of the order of 6. For constant stress experiments, a minimum in the strain rate and a corresponding maximum in the elongational viscosity is found at a Hencky strain of the order of 3, which, although larger than the steady-state value, follows roughly the general trend of the steady-state elongational viscosity. The constitutive analysis also reveals that constant tensile force experiments indicate a larger strain hardening potential than seen in constant elongation rate or constant tensile stress experiments. This may be indicative of the effect of necking under constant elongation rate or constant tensile stress conditions according to the Considère criterion.
Keywords: Rheology, MSF model, Elongational flow, Strain hardening, Low-density polyethylene, Polymer melts, Constant elongational rate, Constant stress, creep, Constant force.
Manfred H. Wagner | Berlin Institute of Technology (TU Berlin) | Germany
8:10 – 9:10
Photo-oxidation of LDPE: Effects on Elongational Viscosity
Autors:
Víctor H. Rolón-Garrido and Manfred H. Wagner
Affiliation:
Chair of Polymer Engineering/Polymer Physics, Berlin Institute of Technology (TU Berlin), Fasanenstrasse 90, D-10623 Berlin, Germany.
Abstract:
Sheets of low-density polyethylene (LDPE) were photo-oxidatively treated at room temperature, and subsequently characterized rheologically in the melt state by shear and uniaxial extensional experiments. For photo-oxidation, a xenon lamp was used to irradiate the samples for times between 1 day and 6 weeks. Linear-viscoelastic characterization was performed in a temperature range of 130 to 220°C to obtain the master curve at 170°C, the reference temperature at which the elongational viscosities were measured. Linear viscoelasticity is increasingly affected by increasing photo-oxidation due to crosslinking of LDPE, as corroborated by an increasing gel fraction as determined by a solvent extraction method. The elongational measurements reveal a strong enhancement of strain hardening until a saturation level is achieved. The elongational data are analyzed in the frame work of two constitutive equations, the rubber-like liquid and the molecular stress function models. Within the experimental window, time-deformation separability is confirmed for all samples, independent of the degree of photo-oxidation.
Keywords: Rheology, MSF model, Elongational flow, Strain hardening, Low-density polyethylene, Polymer melts, Photo-oxidative degradation, Constitutive equations.
Víctor H. Rolón-Garrido | Berlin Institute of Technology (TU Berlin) | Germany
9:10 – 9:40
On the (Ir)Reproducibility of Measurements of Elongational Viscosity Using an SER Universal Testing Platform
Autors:
Petr Filip and Radek Pivokonsky
Affiliation:
Institute of Hydrodynamics, Acad. Sci. Czech Rep., Pod Patankou 5, 166 12 Prague 6, Czech Republic.
Abstract:
An SER Universal Testing Platform represents a widely used instrument determined for the measurement of elongational viscosity of various materials. Apart from an initial pre-selection of materials and an a priori range of extension strain for which this method can be applied, there is a series of other factors substantially influencing quality and reproducibility of the obtained results. They are prevailingly connected with the preparation of the samples and their fixing to the elongation rheometer. Among them it is possible to name an unevenness of sample thickness, appearance of air bubbles within the material studied, slant of fixed sample with respect to the rheometer drums axes. The aim of this contribution is to show the reasons of possible bad reproducibility of elongation measurements and visually determine the ranges of selected parameters within which the measurements are acceptable.
Keywords: Elongational viscosity, SER Universal Testing Platform.
Petr Filip | Institute of Hydrodynamics ASCR | Czech Republic
9:40 – 10:40
Cofee break & Poster section & Exhibition
Rheological Characterization of Degradation and Polycondensation of Poly(ethylene terephthalate) Melt in Air and in Nitrogen
Autors:
Matthias Kruse, Víctor H. Rolón-Garrido and Manfred H. Wagner
Affiliation:
Chair of Polymer Engineering/Polymer Physics, Berlin Institute of Technology (TU Berlin), Fasanenstrasse 90, D-10623 Berlin, Germany.
Abstract:
Three different poly(ethylene terephthalate) (PET) samples based on dimethyl terephthalate or terephthalic acid, were studied in terms of alterations and mutations caused by thermal exposure during rheological characterization. Thermal stability and frequency sweep experiments were performed in the melt state at a temperature of 280°C, and the influence of the atmosphere (air or nitrogen) as well as the effect of sample preparation (pellets molten directly between the plates of the rheometer vs. samples cut from compression molded sheets) were studied. Thermal stability tests reveal a fundamentally different behavior of the storage (G’) and the loss (G”) modulus for measurements in air compared to measurements in a pure nitrogen atmosphere. Samples measured in air show a decrease of both moduli due to thermal degradation, while an unexpected strong increase was observed in nitrogen due to polycondensation. The loading time of the samples caused already a significant change of the rheological properties, which could be reconstructed by extrapolation to zero loading time. Frequency sweep test were significantly affected by the rapid changes of the molecular structure. Frequency sweeps were conducted bidirectional, i.e. by first increasing the angular frequency from 0.05 rad.s-1 to 500 rad.s-1, which was then followed by a decrease from 500 rad.s-1 to 0.05 rad.s-1, and vice versa. These tests confirm the effects of the atmosphere applied, air or nitrogen, causing degradation and condensation, respectively. However, besides these dominating alterations, i.e. reduction of the molecular weight due to chain scission in air and increase of the molecular weight due to condensation reactions in nitrogen, also the opposite effects were detected. This indicates clearly the formation of a bimodal molecular weight distribution whose existence was supported by the rheological characterization of compression molded plates, which were found to show more degradation but also enhanced bimodality.
Keywords: Poly(ethylene terephthalate), Alteration, Thermal stability, Dynamic rheology.
Matthias Kruse | Berlin Institute of Technology (TU Berlin) | Germany
Investigation of Crosslinking Behaviour of Silane Grafted Polyethylene through Rheology
Autors:
Ales 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 Zlin, nam. T. G. Masaryka 275, 762 72 Zlin, Czech Republic.
3) Centre of Polymer Systems, University Institute, Tomas Bata University in Zlin, Nad Ovcirnou 3685, 760 01 Zlin, Czech Republic.
Abstract:
In this work the crosslinking behaviour of two silane-grafted polyethylenes was investigated with respect to time and temperature by using dynamic rheological measurements. It has been found that inhomogeneous character of the crosslinking reaction takes place in both tested samples. By utilization of G’-G” crossover method, it has been found that the sample with initially distinct crosslinking state and short critical crosslinking reaction time has high tendency to create small gels during production of hot water pipes. It has also been revealed that the temperature dependence of the critical time, at which the crosslinking speed is the highest, shows an Arrhenius-type behaviour.
Keywords: Silane grafted polyethylene, Crosslinking behaviour, Gel point.
Ales Obr | SILON s.r.o. | Czech Republic
Shear Induced Electrical Behaviour of Conductive Polymer Composites
Autors:
Zdeněk Starý, Johannes Krückel, Dirk W. Schubert
Affiliation:
Institute of Polymer Materials, Friedrich-Alexander-University Erlangen-Nuremberg, Martensstr. 7, 91058 Erlangen, Germany.
Abstract:
The time-dependent electrical resistance of polymethylmethacrylate containing carbon black was measured under oscillatory shear in the molten state. The electrical signal was oscillating exactly at the doubled frequency of the oscillatory shear deformation. Moreover, the experimental results gave a hint to the development of conductive structures in polymer melts under shear deformation. It was shown that the flow induced destruction of conductive paths dominates over the flow induced build-up in the beginning of the shear deformations. However, for longer times both competitive effects reach a dynamic equilibrium and only the thermally induced build-up of pathways influences the changes in the composite resistance during the shear. Furthermore, the oscillating electrical response depends clearly on the deformation amplitude applied. A simple physical model describing the behaviour of conductive pathways under shear deformation was derived and utilized for the description of the experimental data.
Keywords: Composites, Electrical resistance, Oscillatory shear.
Zdeněk Starý | Friedrich-Alexander University Erlangen-Nürnberg | Germany
Rheological Evaluation of Melt Blown Polymer Melt
Autors:
Jiri Drabek 1) and Martin Zatloukal 1, 2)
Affiliations:
1) Polymer Centre, Faculty of Technology, Tomas Bata University in Zlin, nam. T. G. Masaryka 275, 762 72 Zlin, Czech Republic.
2) Centre of Polymer Systems, University Institute, Tomas Bata University in Zlin, Nad Ovcirnou 3685, 760 01 Zlin, Czech Republic.
Abstract:
In this work, shear and uniaxial extensional viscosities of polypropylene melt blown sample with melt flow rate equal to 450 g/10min have been determined in wide deformation rate range by using capillary rheometry and novel orifice die design and the capability of recently proposed generalized Newtonian model to describe the measured experimental data has been tested.
Keywords: Shear viscosity, Extensional viscosity, Capillary rheometry, Generalized Newtonian law, Rheology, Polyolefines.
Jiri Drabek | Tomas Bata University in Zlin | Czech Republic
Effect of Strain on Viscoelastic Behavior of Fresh, Swelled and Mineralized PVP-CMC Hydrogel
Autors:
Nabanita Saha 1, 2), Radek Vyroubal 1), Rushita Shah 1), Takeshi Kitano 1, 2) and Petr Saha 1, 2)
Affiliations:
1) Polymer Centre, Faculty of Technology, Tomas Bata University in Zlin, nam. T. G. Masaryka 275, Zlin 762 72, Czech Republic.
2) Centre of Polymer Systems, University Institute, Tomas Bata University in Zlin, Nad Ovcirnou 3685, 760 01 Zlin, Czech Republic.
Abstract:
Mineralization of calcium carbonate (CaCO3) in hydrogel matrix is one of the most interesting topics of research by material scientists for the development of bio-inspired polymeric biomaterial for biomedical applications especially for bone tissue regeneration. As per our knowledge there was no work reported about rheological properties of CaCO3 mineralized hydrogel though some works have done on mineralization of CaCO3 in various gel membranes, and also it was reported about the viscoelastic properties of Agarose, Cellulose, PVA and PVP-CMC hydrogels. This paper mainly focuses about the effect of strain on viscoelastic properties of fresh, swelled and mineralized (CaCO3) PVP-CMC hydrogel. All these three types of hydrogel sustain (or keep) strictly the elastic properties when low strain (1%) is applied, but at higher strain (10%) the viscoelastic moduli (G’ and G”) show significant change, and the nature of these materials turned from elastic to viscous.
Keywords: Hydrogels, Strain, Angular frequency, Viscoelastic, Swelling, Mineralization.
Takeshi Kitano | Tomas Bata University in Zlin | Czech Republic
Characterization of Die Drool Sample Produced by HDPE Melt Extrusion
Autors:
Jan Musil 1) and Martin Zatloukal 1, 2)
Affiliations:
1) Centre of Polymer Systems, University Institute, Tomas Bata University in Zlin, Nad Ovcirnou 3685, 760 01 Zlin, Czech Republic.
2) Polymer Centre, Faculty of Technology, Tomas Bata University in Zlin, nam. T. G. Masaryka 275, 762 72 Zlin, Czech Republic.
Abstract:
In this work, flow induced molecular weight fractionation experiment was performed for HDPE polymer on specially designed laboratory extrusion setup. Die drool sample, accumulated at the die exit face, together with virgin pellets were consequently characterized experimentally by gel permeable chromatography, differential scanning calorimetry and rheology as well as theoretically by recently proposed generalized Newtonian model.
Keywords: Flow induced molecular weight fractionation, Die drool, Flow instabilities, Extrusion, Rheology, Polyolefines, Wall slip.
Jan Musil | Tomas Bata University in Zlin | Czech Republic
Effect of Rheological Parameters on Curing Rate during NBR Injection Molding
Autors:
Kamil Kyas, Michal Stanek, David Manas and Adam Skrobak
Affiliation:
Tomas Bata University in Zlín, nam. T.G. Masaryka 5555, 760 01 Zlín, Czech Republic.
Abstract:
In this work, non-isothermal injection molding process for NBR rubber mixture considering Isayev–Deng curing kinetic model, generalized Newtonian model with Carreau-WLF viscosity was modeled by using finite element method in order to understand the effect of volume flow rate, index of non-Newtonian behavior and relaxation time on the temperature profile and curing rate. It was found that for specific geometry and processing conditions, increase in relaxation time or in the index of non-Newtonian behavior increases the curing rate due to viscous dissipation taking place at the flow domain walls.
Keywords: Injection molding, Rubber, Computational analysis, Mold.
Kamil Kyas | Tomas Bata University in Zlin | Czech Republic
Evaluation of Variational Principle Based Model for LDPE Large Scale Film Blowing Process
Autors:
Roman Kolarik 1) and Martin Zatloukal 1, 2)
Affiliations:
1) Centre of Polymer Systems, University Institute, Tomas Bata University in Zlin, Nad Ovcirnou 3685, 760 01 Zlin, Czech Republic.
2) Polymer Centre, Faculty of Technology, Tomas Bata University in Zlin, nam. T. G. Masaryka 275, 762 72 Zlin, Czech Republic.
Abstract:
In this work, variational principle based film blowing model combined with Pearson and Petrie formulation, considering non-isothermal processing conditions and novel generalized Newtonian model allowing to capture steady shear and uniaxial extensional viscosities has been validated by using experimentally determined bubble shape and velocity profile for LDPE sample on large scale film blowing line. It has been revealed that the minute change in the flow activation energy can significantly influence the film stretching level.
Keywords: Film blowing process, LDPE, Flow activation energy.
Roman Kolarik | Tomas Bata University in Zlin | Czech Republic
Deformation Theory of an Electro-conductive Composite Composed of Entangled Network of Carbon Nanotubes Embedded in Elastic Polyurethane
Autors:
Petr Slobodian 1, 2), Pavel Riha 3), Robert Olejnik 1, 2) and Petr Saha 1, 2)
Affiliations:
1) Polymer Centre, Faculty of Technology, Tomas Bata University in Zlin, nam T. G. Masaryka 275, 762 72 Zlin, Czech Republic.
2) Centre of Polymer Systems, University Institute, Tomas Bata University in Zlin, Nad Ovcirnou 3685, 760 01 Zlin, Czech Republic.
3) Institute of Hydrodynamics, Academy of Sciences, Pod Patankou 30/5, 166 12 Prague 6, Czech Republic.
Abstract:
A strain sensing polymer composite consisting of a network of entangled multi-walled carbon nanotubes in a thermoplastic polyurethane elastomer is tested by tensile and bending deformation. The composite is prepared by taking a non-woven polyurethane filter membrane, enmeshing it with carbon nanotubes and melding them together. The testing has shown that the material can be elongated as much as 400% during which the electrical resistance is increased more than 270 times. To describe the composite strain dependent resistance, a rheological model is proposed which takes into account a decrease of local contact forces between nanotubes as well as the reduction of number of contacts with deformation. The theory is used for description of sensing element deformation and resistance when simple elongation and repeated bending is exerted.
Keywords: Carbon nanotubes, Entangled network, Mechanical properties, Cyclic deformation.
Petr Slobodian | Tomas Bata University in Zlin | Czech Republic
Morphology, Absorptivity and Viscoelastic Properties of Mineralized PVP-CMC Hydrogel
Autors:
Nabanita Saha 1, 2), Rushita Shah 1), Radek Vyroubal 1), Takeshi Kitano 1, 2) and Petr Saha 1, 2)
Affiliations:
1) Polymer Centre, Faculty of Technology, Tomas Bata University in Zlin, nam. T. G. Masaryka 275, Zlin 762 72, Czech Republic.
2) Centre of Polymer Systems, University Institute, Tomas Bata University in Zlin, Nad Ovcirnou 3685, 760 01 Zlin, Czech Republic.
Abstract:
A simple liquid diffusion mineralization technique was applied for the incorporation of calcium carbonate (CaCO3) in PVP-CMC hydrogel. The hydrogel was prepared 6.5 mm thick to achieve around 1 mm thick sample after mineralization of hydrogel matrix with calcite. The calcite crystals were round shaped and organized as building blocks inside the porous three dimensional cross linked structure of the PVP-CMC hydrogel. The present study was designed to evaluate the properties of mineralized (calcite) hydrogel with respect to freshly prepared hydrogel and those swelled in water (H2O) after drying. The viscoelastic properties of swelled and mineralized samples were reported though the dry PVP-CMC hydrogel were swelled and mineralized with calcite until 150 min. It is observed that there is not much difference in elastic property of fresh and 60 min mineralized hydrogels but the values of elastic property are decreased in the case of swelled hydrogels. It is interesting that in case of swelled samples the values of complex viscosity (η*) are increased with the increase of swelling time after 90 min but in case of calcite hydrogel the values (η*) are gradually decreased with the increase of time.
Keywords: Mineralized hydrogel, Viscoelastic properties, Absorptivity, Calcite, PVP, CMC.
Rushita Shah | Tomas Bata University in Zlin | Czech Republic
Quality of Nanofibrous Web in Dependence on the Preparation of Polymer Solutions
Autors:
Petra Peer and Petr Filip
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 compare the nanofibrous webs in dependence on the preparation of polymer solution from which are created. The solutions formed by polyvinylbutyral (PVB) solved in methanol at different concentrations were prepared in two ways – either using a vibrating shaker or a magnetic stirrer. The principal difference consists in invasive and non-invasive effect of the individual approaches and the consecutive mild changes in the molecular architecture. The rheological characterization of both types of PVB solutions was carried out an electrocell housed in the rotational rheometer. The nanofibrous webs obtained by an electrospinning process were analyzed by means of scanning electron microscopy. There was found a correspondence between the differences in quality of the nanofibrous webs and the rheological characteristics of either solutions.
Keywords: Electrorheology, Nanofibrous web, Polymer solution.
Petra Peer | Institute of Hydrodynamics ASCR | Czech Republic
The Effect of Nanofiber Based Filter Morphology on Bacteria Deactivation during Water Filtration
Autors:
Dusan Kimmer 1), Ivo Vincent 1), Jaroslav Lev 2), Libor Kalhotka 3), Premysl Mikula 4), Radka Korinkova 5), Wannes Sambaer 6, 7) and Martin Zatloukal 6, 7)
Affiliations:
1) SPUR a.s., trida Tomase Bati 299, Louky,763 02 Zlin, Czech Republic.
2) ASIO spol. s r.o., Turanka 1, 627 00 Brno, Czech Republic.
3) Mendel University in Brno, Faculty of Agronomy, Zemedelska 1, 613 00 Brno, Czech Republic.
4) Institute of Botany of the ASCR, Lidicka 25/27, 602 00 Brno, Czech Republic.
5) COC s.r.o., 533 54 Rybitvi, Czech Republic.
6) Polymer Centre, Faculty of Technology, Tomas Bata University in Zlin, nam. T. G. Masaryka 275, 762 72 Zlin, Czech Republic.
7) Centre of Polymer Systems, University Institute, Tomas Bata University in Zlin, Nad Ovcirnou 3685, 760 01 Zlin, Czech Republic.
Abstract:
Procedures permitting to prepare homogeneous functionalized nanofibre structures based on polyurethanes modified by phthalocyanines (PCs) by employing a suitable combination of variables during the electrospinning process are presented. Compared are filtration and bacteria deactivation properties of open and planar nanostructures with PCs embedded into polyurethane chain by a covalent bond protecting the release of active organic compound during the filtration process. Finding that the morphology of functionalized nanofibre structures have an effect on bacterial growth was confirmed by microbiological and physico-chemical analyses, such as the inoculation in a nutrient agar culture medium and flow cytometry.
Keywords: Nanofibre, Nanostructure, Electrospinning, Phthalocyanines, Bacteria deactivation.
Dusan Kimmer | SPUR a.s. | Czech Republic
INTRODUCTION OF NOVEL RHEOLOGICAL TOOLS
(Chairman: Joao M. Maia)
10:40 – 11:10
The possibilities of a rheometer with two EC motors: MCR 702 TwinDrive™
Autor:
Michael Ringhofer
Affiliation:
Anton Paar GmbH, Anton-Paar-Str. 20, 8054 Graz, Austria.
Abstract:
Anton Paar introduces a rheometry revolution: MCR 702 with modular TwinDriveTM technology. This is the world’s first rheometer to cover all possible rheological applications – with an accuracy of 1 nNm and features like the IsoLign Piezo flange, offering measuring gap control down to an unprecedented size of 10 nm.
Anton Paar’s TwinDriveTM technology combines two powerful synchronous EC (Electrically Commutated) motor units in a modular setup: The upper EC motor in the rheometer is permanent; the lower EC motor can be extracted and integrated at will. Due to the EC motor’s renowned dynamism and precision, users have several options of how to employ these motor units to fit their specific requirements.
MCR 702 with fully integrated TwinDriveTM technology, can be operated in several test modes and covers all rheological applications – past, present and future.
2EC mode
In this mode, the rheometer employs both EC motors as drive units and torque transducers, optionally rotating in opposite or parallel directions. Doubled EC motors extend the scope of testing options, e.g. with optional counter-rotation for enhanced rheo-microscopy. MCR 702 TwinDrive™ can be operated with both motors’ maximum shear rates combined and is optionally employed for extensional rheology applications or tests with parallel rotation at different speeds.
The 2EC mode also enables users to employ the motors in a more synchronized fashion, making “different demands” on each of them. Because of the EC motors’ outstanding precision, one motor is easily brought to a standstill and operated solely as a torque transducer, while the other motor is used as a drive unit only.
EC mode
In the EC mode, the lower motor unit is easily removed in accordance with individual application needs. After the extraction of the lower motor, the instrument can be operated as a single-drive rheometer, making the most of the single EC motor’s TruStrainTM capability and enabling “classic” stress-controlled tests.
IsoLign: Complete gap control
MCR 702 TwinDrive™ is the first rheometer to offer nano-scale precision on several counts – such as low-torque measurements down to a minimum of 1 nNm and the control of angular deflections down to 100 nrad. Now this peak precision also extends to the system’s measuring gap control: The new IsoLign Piezo flange performs gap size changes as small as 10 nm. Based on a system of 3 Piezo elements in the flange of the measuring chamber reception, IsoLign is reliably employed in all TwinDrive™ test modes.
Keywords: Rotational rheometry.
Michael Ringhofer | Anton Paar GmbH | Austria
11:10 – 11:40
Relevant Process Parameters for Twin Screw Compounding
Autors:
Bernd Jakob and Tom Geilen
Affiliation:
ThermoFisher Scientific, Dieselstr. 4, 76227 Karlsruhe, Germany.
Abstract:
Screw conveyors have a long history. The first screw conveyor was invented by Archimedes († 212 BC) and is still in use for irrigation. Industrial use of screw conveyors started in middle of the 19th century. Significant industrial utilization polymer processing began in the 1st half of the 20th century. The single extruders are used to melt and shape the polymers but they are limited in their performance. They operate with a complete filled barrel under pressure so no venting or split feeding is possible. Also their mixing capabilities are limited. To satisfy the growing demands in the polymer industry for continuous mixing R. Erdmenger developed a co-rotating twin screw compounder with intermeshing, self wiping screws and got it patented in 1944. Various compounding tasks and the process dependent and independent parameters will be discussed in this paper. An overview how to optimize the compounding process and the screw configuration is also introduced. An automated measurement of the retention time and how to scale up the test of a small laboratory compounder to bigger pilot plant or smaller scale production extruder is presented.
Keywords: Extrusion, Compounding, Residence time, Scale up.
Bernd Jakob | ThermoFisher Scientific | Germany
11:40 – 13:10
Lunch & Exhibition
EXTRUSION INSTABILITIES IN PLASTICS INDUSTRY
(Chairman: Savvas Hatzikiriakos)
13:10 – 13:50
Plenary lecture
Die Drool and Die Drool Theory
Autors:
A. M. Schmalzer 1, 2) and A. Jeffrey Giacomin 1, 2)
Affiliations:
1) Rheology Research Center, University of Wisconsin 1513 University Avenue, Madison, WI 53706, USA.
2) Mechanical Engineering Department, University of Wisconsin 1513 University Avenue, Madison, WI 53706, USA.
Abstract:
When molten plastic is extruded from a die, it sometimes collects on the open face of the die. Known as die drool, this phenomenon costs plastics manufacturers by requiring die cleaning. This has been attributed to many causes, but none of these has led to an equation for the drool rate. In this work we provide an exact analytical solution for the drool rate, and we base this solution on a postulate of a cohesive slip layer near the die walls. We thus attribute die drool to cohesive failure within the fluid at an internal surface where the fluid slips on itself. We adimensionalize the drool rate with the production rate, and call this the build up ratio, BR. We provide an exact analytical solution for BR when the cohesive slip layer either sticks at the wall. We examine the slit geometry corresponding to sheet or film extrusion.
Keywords: Die drool, Die lip build up, Cohesive failure, Melt fracture, Sheet extrusion.
A. Jeffrey Giacomin | University of Wisconsin-Madison | USA
13:50 – 14:20
Historical Review of Die Drool Phenomenon during Plastics Extrusion
Autors:
Jan Musil 1) and Martin Zatloukal 1, 2)
Affiliations:
1) Centre of Polymer Systems, University Institute, Tomas Bata University in Zlin, Nad Ovcirnou 3685, 760 01 Zlin, Czech Republic.
2) Polymer Centre, Faculty of Technology, Tomas Bata University in Zlin, nam. T. G. Masaryka 275, 762 72 Zlin, Czech Republic.
Abstract:
Die drool phenomenon is defined as unwanted spontaneous accumulation of extruded polymer melt on open faces of extrusion die during extrusion process. Such accumulated material builds up on the die exit and frequently or continually sticks onto the extruded product and thus damages it. Since die drool appears, extrusion process must be shut down and die exit must be manually cleaned which is time and money consuming. Although die drool is complex phenomenon and its formation mechanism is not fully understood yet, variety of proposed explanations of its formation mechanism and also many ways to its elimination can be found in open literature. Our review presents in historical order breakthrough works in the field of die drool research, shows many ways to suppress it, introduces methods for its quantitative evaluation and composition analysis and summarizes theories of die drool formation mechanism which can be helpful for extrusion experts.
Keywords: Die drool, Die build up, Flow instabilities, Extrusion, Polymer melt.
Jan Musil | Tomas Bata University in Zlin | Czech Republic
14:20 – 14:50
Numerical Simulation of Extrusion: A Good Tool for Troubleshooting Extrusion Problems
Autors:
Birane Touré 1), Jiri Svabik 2), Michael Veaux 1), Walid Bahloul 1), Jean-Pierre Mascia 3), Mikael Abéguilé 1), Thierry Seux 4) and Stig-Jrale Hauko 5)
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) Nexans France, 2, Rue des Marguerites, 01003 Bourg-en-Bresse, France.
4) Nexans France, 29, Rue Pré Gaudry-69353 Lyon cedex 07, France.
5) Nexans Norway AS, Klingavn. 2-Serviceboks 1009, N-7809 Namsos.
Abstract:
The paper describes different studies linked to extrusion problems encountered during production in the cable industry. Extrusion simulation or rheology analysis can be used to understand the origin of the problems in cable manufacturing and to set up durable industrial solutions by selecting the appropriate compounds, optimizing screw profiles, modifying the geometries of the tooling or adapting the processing conditions. Our investigations based on the COMPUPLAST® Virtual Extrusion Laboratory™ software, have brought large understanding and these investigations are cheaper and faster alternatives to real experiments (trials/errors) when analyzing and optimizing extrusion processes. Three examples are presented in the paper.
Keywords: Extrusion, Numerical simulation, Troubleshooting, Boundary conditions, Cooling, Wearing, Flight clearance, Extruder performances.
Jiri Svabik | Compuplast International, Inc. | Czech Republic
14:50 – 15:20
Refreshment & Exhibition
MODELING AND SIMULATION
(Chairman: Olga S. Carneiro)
15:20 – 15:50
Influence of the Power Law Index on the Fiber Breakage during Injection Molding by Numerical Simulations
Autors:
Frederik Desplentere, Wim Six, Hilde Bonte and Eric Debrabandere
Affiliation:
Department of Mechanical Engineering, Katholieke Hogeschool Brugge Oostende (Association KU Leuven) Zeedijk 101, B-8400 Ostend, Belgium.
Abstract:
In predictive engineering for polymer processes, the proper prediction of material microstructure from known processing conditions and constituent material properties is a critical step forward properly predicting bulk properties in the finished composite.
Operating within the context of long-fiber thermoplastics (LFT, length < 15mm) this investigation concentrates on the influence of the power law index on the final fiber length distribution within the injection molded part. To realize this, the Autodesk Simulation Moldflow Insight Scandium 2013 software has been used. In this software, a fiber breakage algorithm is available from this release on. Using virtual material data with realistic viscosity levels allows to separate the influence of the power law index on the fiber breakage from the other material and process parameters. Applying standard settings for the fiber breakage parameters results in an obvious influence on the fiber length distribution through the thickness of the part and also as function of position in the part. Finally, the influence of the shear rate constant within the fiber breakage model has been investigated illustrating the possibility to fit the virtual fiber length distribution to the possible experimentally available data.
Keywords: Long fiber thermoplastic, Fiber length distribution, Moldflow, Power law index.
Frederik Desplentere | KHBO(Association KU Leuven) | Belgium
15:50 – 16:20
Investigation of Heat Transfer in 9-Layer Film Blowing Process by using Variational Principles
Autors:
Roman Kolarik 1) and Martin Zatloukal1, 2)
Affiliations:
1) Centre of Polymer Systems, University Institute, Tomas Bata University in Zlin, Nad Ovcirnou 3685, 760 01 Zlin, Czech Republic.
2) Polymer Centre, Faculty of Technology, Tomas Bata University in Zlin, nam. T. G. Masaryka 275, 762 72 Zlin, Czech Republic.
Abstract:
In this work, coextrusion experiments utilizing an industrial 9-layer Brampton Engineering coextrusion film blowing line has been performed under different processing conditions (low/high air cooling intensity) in order to evaluate variational principles based modeling approach using energy equation utilizing variable heat transfer coefficient along the multi-layer bubble. It has been revealed that the variational principle based model can describe the bubble shape and temperature profile reasonably well even if the multi-layer film has been viewed as the static elastic membrane characterized only by one material parameter – bubble compliance J, which was not allow to vary along the bubble. Moreover, it has been found that if the freezeline height becomes long, heat transfer coefficient starts to vary significantly along the bubble which has crucial impact on the temperature profile along the multi-layer bubble. The performed theoretical parametric study revealed that increase in blow-up ratio or decrease in bubble curvature and air temperature causing bubble cooling efficiency increases, which allows to cooled down the multi-layer bubble for the given freezeline height to solidification temperature by smaller amount of the air volume flow rate.
Keywords: Polymer, Coextrusion, Multi-layer film blowing, Heat transfer coefficient, Non-isothermal process.
Roman Kolarik | Tomas Bata University in Zlin | Czech Republic
16:20 – 16:50
Effect of Particle-Fiber Friction Coefficient on Ultrafine Aerosol Particles Clogging in Nanofiber Based Filter
Autors:
Wannes Sambaer 1, 2), Martin Zatloukal 1, 2) and Dusan Kimmer 3)
Affiliations:
1) Polymer Centre, Faculty of Technology, Tomas Bata University in Zlin, TGM 275, 762 72 Zlin, Czech Republic.
2) Centre of Polymer Systems, University Institute, Tomas Bata University in Zlin, Nad Ovcirnou 3685, 760 01 Zlin, Czech Republic.
3) SPUR a.s., trida Tomase Bati 299, Louky, 763 02 Zlin, Czech Republic.
Abstract:
Realistic SEM image based 3D filter model considering transition/free molecular flow regime, Brownian diffusion, aerodynamic slip, particle-fiber and particle-particle interactions together with a novel Euclidian distance map based methodology for the pressure drop calculation has been utilized for a polyurethane nanofiber based filter prepared via electrospinning process in order to more deeply understand the effect of particle-fiber friction coefficient on filter clogging and basic filter characteristics. Based on the performed theoretical analysis, it has been revealed that the increase in the fiber-particle friction coefficient causes, firstly, more weaker particle penetration in the filter, creation of dense top layers and generation of higher pressure drop (surface filtration) in comparison with lower particle-fiber friction coefficient filter for which deeper particle penetration takes place (depth filtration), secondly, higher filtration efficiency, thirdly, higher quality factor and finally, higher quality factor sensitivity to the increased collected particle mass. Moreover, it has been revealed that even if the particle-fiber friction coefficient is different, the cake morphology is very similar.
Keywords: Nanofibers, Electrospinning, 3D Modeling, Clogging.
Wannes Sambaer | Tomas Bata University in Zlin | Czech Republic
16:50
End of the conference