* The abstracts are available for each conference contribution when you click on the corresponding title.
July 14, 2007
7:30 – 7:55
Registration
7:55 – 8:00
Welcome
8:00 – 9:00
Experimental Investigations of the Entry Flow of Polyethylene Using Laser-Doppler Velocimetry
Autors:
D. Hertel and H. Münstedt
Affiliation:
Institute of Polymer Materials, University Erlangen-Nürnberg, Martensstraße 7, 91058 Erlangen, Germany.
Abstract:
Laser-Doppler velocimetry allows to investigate the flow of polymer melts with high spatial and temporal resolution. Therefore, this method can be applied to get a deeper insight into the flow behavior of polymer melts in a slit die which is widely used in rheology and processing.
This technique is applied for analyzing the viscoelastic flow behavior of polyethylene in a planar contraction geometry. The materials investigated are two polyethylenes, a LLDPE and a LDPE.
Special attention is paid to the entry flow of these materials. Within the die entrance region two phenomena were investigated: the secondary flow regions in the corners of the die and the so-called velocity overshoot within the main flow. For these two effects the dependence on temperature, throughput and die geometry was analysed.
Daniela Hertel | University of Erlangen | Germany
9:00 – 9:30
Simulation of flows of LDPE using the Molecular Stress Function model with Convective Constraint Release
Autor:
P. Olley
Affiliation:
School of Engineering Technology and Design, University of Bradford, Bradford, UK – .
Abstract:
The Molecular Stress Function constitutive model has been demonstrated by Wagner to fit elongational and shear viscosities, and First and Second Normal stress differences for a variety of polymer melts, when used with a Convective Constraint Release mechanism [1]. A modification to the CCR mechanism was shown to give more accurate representation of corner vortices in an abrupt contraction flow [2]. Variants of this model are investigated and it is shown that models which give virtually identical response in viscometric tests can give significantly different response in a complex flow. A number of alternative formulations are considered and their efficacy is compared with the model described in [2].
References:
[1] M.H. Wagner, P. Rubio, and H. Bastian, J. Rheol, 45 (2001), 1387.
[2] P. Olley and M.H. Wagner, J. non-Newt. Fluid Mech., 135 (2006), 68.
Peter Olley | University of Bradford | UK
9:30 – 10:00
Cofee break & Exhibition
10:00 – 10:30
Coupled 3D Stress, Velocity and Temperature Field Measurements for Flowing Linear and Branched Polymer Melts
Autors:
T. Gough a), R. Spares b), A.L. Kelly c) and P. D. Coates d)
Affiliation:
IRC in Polymer Engineering, University of Bradford, Bradford BD7 1DP, UK.
Contacts:
a) Corresponding author:
b)
c)
d)
Abstract:
Stress, velocity and temperature field measurements are presented for contraction flows of well characterised linear and branched materials through abrupt contraction and x-slot flow cells. The techniques utilised include stress birefringence, particle tracking velocimetry and thermocouple meshes. In addition to the more typical measurements in the streamwise/normal (x-y) plane data in the streamwise/cross-stream (x-z) plane have also been obtained providing the first detailed measurements of the three dimensional nature of these flows. Measurements of stress, velocity and molecular conformation (via small angle neutron scattering) for a linear material in a recirculation x-slot flow cell (providing pure extensional flow) will also be presented.
Tim Gough | University of Bradford | UK
10:30 – 11:00
Progress in Viscoelastic Modeling of Polymer Processing with Respect to Free Surface Flow Instabilities
Autors:
M. Zatloukal a), R. Kolarik b) and P. Saha c)
Affiliation:
Polymer Centre, Faculty of Technology, Tomas Bata University in Zlín, TGM 275, Zlin 762 72, Czech Republic.
Contacts:
a) Corresponding author:
b)
c)
Abstract:
The effect of processing conditions, die design and material characteristics on the flow stability in both, extrusion dies and post die areas has been investigated theoretically by using Finite Element Method or variational principles and the theoretical predictions were compared with the corresponding experimental data. The specific attention has been paid to film blowing instabilities, die drool phenomenon and coextrusion interfacial instabilities.
Martin Zatloukal | Tomas Bata University in Zlin | Czech Republic
11:00 – 11:30
A 3D Study of Flow Through a Spiral Die Geometry
Autors:
J. Vlcek 1, a) and J. Perdikoulias 2, b)
Affiliations:
1) Compuplast International, Inc., Nerudova 158, P.O. Box 24, 760 01 Zlín, Czech Republic.
2) Compuplast Canada, 5333 Forest Hill Drive, Mississauga, ON, Canada, L5M 5A7.
Contacts:
a) Corresponding author:
b)
Abstract:
There is presented a study in which details of flow through a spiral die are shown. Based on this detail study effects like port lines, degradation and various film strength can be explained.
Jiri Vlcek | Compuplast International | Czech Republic
11:30 – 13:00
Lunch & Exhibition
13:00 – 13:30
Effect of Screw Geometries on Extrusion of Wood-HDPE Blends
Autors:
K. Xiao 1, a) and C. Tzoganakis 2, b)
Affiliations:
1) Brampton Engineering Inc., Brampton, Ontario, Canada.
2) Department of Chemical Engineering, University of Waterloo, Waterloo, Ontario, Canada.
Contacts:
a) Corresponding author:
b)
Abstract:
The wood-polymer composite market has grown exponentially in the past 10 years. These composites have been used in many commercial areas to replace wood, such as the outdoor decking and the automotive industry. The main advantage of wood-polymer over wood is its higher resistance to decay. Since wood fibers are strong, light-weight, abundant, nonabrasive, non-hazardous, and inexpensive, they can also serve as an excellent reinforcer for plastics.
So far, very limited studies have been done on the extrusion characteristics of wood-filled resins. A better understanding of the processing behaviour of these materials will lead to better design of polymer processing equipment. This will, in turn, improve the quality of the final product. This paper investigates the rheological properties and their influences on extrusion characteristics of 25%, 36% and 50% wood-filled HDPE composites. The results will also be compared to those of the base virgin HDPE. Three screw geometries were used, and the effects of feed depths, the compression ratios, and the metering depths were compared. The extrusion characteristics examined included output, pressures and melting profiles. It was found that, due to its partially filled phenomenon, the solid conveying section dominates the extrusion behaviour of the wood-filled resins.
Karen Xiao | Brampton Engineering | Canada
13:30 – 14:00
Investigating Interfacial Instability in Multilayer Blown Film
Autor:
K. Xiao
Affiliation:
Brampton Engineering Inc., Brampton, Ontario, Canada.
Contact:
Corresponding author:
Abstract:
Technological advancements in both machinery and resin design have leveraged multilayer coextrusion to be the most viable method of obtaining different structures. Interfacial instability severely limits the processing window of some equipment. Many processors consider it to be one of the biggest challenges of multilayer coextrusion. Material properties and die geometry can each contribute to interfacial instability.
We used a Brampton Engineering 7-layer Streamlined Coextrusion Die (SCD™) with two different die geometries to study the onset of interfacial instability. We studied two structures: 1) A PE (outside)/Tie/PE structure, and 2) a PA (outside)/Tie/PE structure. For the first structure, we varied the outside layer from 10%-50% whereas for the second structure, we varied the nylon layer from 8%-20% while keeping everything else the same. Our results showed that for polyethylene materials, interfacial instability occurred even if the viscosities were matched. Equipment designers and processors must therefore take into account the differences in elongational viscosities of materials. Since LDPE had the highest elongational viscosity, it was, in our experiment, the most prone to interfacial instability. For the nylon structure, generally speaking, higher viscosity nylons showed less interfacial instability.
Karen Xiao | Brampton Engineering | Canada
14:00 – 14:30
Extrusion Melt Temperature Field Measurement
Autors:
A. L. Kelly a), E. C. Brown b) and P. D. Coates c)
Affiliation:
IRC in Polymer Science & Technology, School of Engineering, Design & Technology, University of Bradford, Bradford, UK, BD7 1DP.
Contacts:
a) Corresponding author:
b)
c)
Abstract:
Melt temperature fields have been measured using a novel thermocouple grid technique. Results are presented from single and twin screw extrusion, examining the effect of polymer type, extruder thoughput, screw design and die head pressure.
Adrian Kelly | University of Bradford | UK
14:30 – 15:00
Cofee break & Exhibition
15:00 – 15:30
FLOW AND MIXING IN A VARIABLE SPEED CO-ROTATING SELF-WIPING TWIN-SCREW EXTRUDER
Autors:
S. Zhu 1), C. Tzoganakis 1, a), T. Shigeishi 2) and K. Tikara 2, b)
Affiliations:
1) Department of Chemical Engineering, University of Waterloo, 200 University Avenue West, Waterloo, Ontario, Canada.
2) Japan Steel Works, Hiroshima, Japan.
Contacts:
a) Corresponding author:
b)
Abstract:
The flow field and mixing pattern in a variable speed corotating intermeshing twin-screw extruder is studied. In this extruder, the two screws have different number of flights and rotate at different speeds. Results from numerical simulations and flow visualization experiments suggest that this extruder exhibits superior distributive mixing in comparison with a regular corotatingg twin-screw in which the screws are identical and rotate at the same speed. In addition, this new screw design exhibits a more positive flow displacement action and a shorter average residence time.
Costas Tzoganakis | University of Waterloo | Canada
15:30 – 16:00
Automatic Design in Profile Extrusion: Flow Balance and Cooling
Autors:
J. M. Nóbrega a) and O. S. Carneiro b)
Affiliation:
IPC/I3N-Institute for Polymers and Composites, Department of Polymer Engineering, University of Minho, Campus de Azurém, 4800-058 Guimarães, Portugal.
Contacts:
a) Corresponding author:
b)
Abstract:
The die and the calibration system are the extrusion line components that play a central role in the establishment of the product dimensions, morphology and properties and are also those that establish the maximum allowable production rate. Currently, and do to the availability of software packages for the mathematical modelling of polymer melt flows, the trial-and-error design approach, usually employed for extrusions dies and calibrators, is being progressively transformed from experimental into a numerical based operation being, however, still dependent on the designer’s experience. The advantages of these approaches are an overall reduction in the cost of the project and a higher probability of finding the optimal solution. Recently, there is a trend towards the automatic design concept. The idea is to turn the die design fully automatic, i.e., without any user intervention, and to guarantee the achievement of the optimal solution. This work describes the current state of the numerical codes that have been developed, by the authors, to aid the design of extrusion dies and calibrators for thermoplastic profile extrusion, based on the automatic design concept.
Miguel Nobrega | University of Minho | Portugal
18:30
Conference dinner
July 15, 2007
8:00 – 8:30
Viscoelastic properties of electrorheological fluids based on urea modified silica nanoparticles
Autors:
V. Pavlínek a), T. Belza, M. Stěnička and P. Sáha
Affiliation:
Tomas Bata University in Zlín, Polymer Centre, TGM 275, 762 72 Zlín, Czech Republic.
Contact:
a) Corresponding author:
Abstract:
Concentration and temperature dependence of the viscoelastic properties of suspensions of urea modified silica nanoparticles during transition from liquid to quasi-solid state in the absence or presence of electric field has been investigated. In the absence of electric field elasticity of suspensions rises with nanoparticle concentration as a result of more intensive particle interactions and storage modulus became dominant over loss one. When temperature is increased loss modulus starts to prevail again due to lowering of host fluid viscosity. There has been found transition temperature at which transition from liquid to quasi-solid state and vice versa sets in.
Vladimir Pavlinek | Tomas Bata University in Zlin | Czech Republic
8:30 – 9:00
Viscoelastic Effects in the Flow of Polymeric Fluids Through Beds of Solid Particles
Autors:
I. Machač a), B. Šiška b) and M. Simon c)
Affiliation:
University of Pardubice, Chemical Engineering Department, Faculty of Chemical Technology, nám. Čs. legií 565, 532 10 Pardubice, Czech Republic.
Contacts:
a) Corresponding author:
b)
c)
Abstract:
Polymeric fluids have generally a viscoelastic character that is responsible for a number of unusual phenomena not observed with purely viscous fluids. In this lecture, the manifestation of viscoelastic effects in the flow through fixed, fluidized and settling beds of solid particles is compared.
Ivan Machac | University of Pardubice | Czech Republic
8:30 – 9:00
Rheometry of the Fine Concentrated Suspensions
Autors:
F. Rieger a) and J. Moravec b)
Affiliation:
Czech Technical University in Prague, Faculty of Mechanical Engineering, Department of Process Engineering, Technická 4, 166 07 Prague 6, Czech Republic.
Contacts:
a) Corresponding author:
b)
Abstract:
The fine highly concentrated suspensions are often met in process industries. The Bingham model can be frequently used for description of their rheological behavior. The paper deals with evaluation of the Bingham model parameters from measurements on the rotational viscometer with coaxial cylinders. The combined Bingham model is proposed for description of rheological behavior in wide range of shear rates. The theoretical conclusions are illustrated on measurements with chalk and clay suspensions.
Frantisek Rieger | Czech Technical University in Prague | Czech Republic
9:00 – 10:30
Cofee break & Poster section & Exhibition
10:30 – 11:00
Effects of Mixed Compatibilizers on Morphology and Rheological Properties of Polystyrene/Polyolefin Blends
Autors:
J. Mikesova 1, a), Z. Stary 2, b) and I. Fortelny 1, c)
Affiliations:
1) Institute of Macromolecular Chemistry AV CR, v. v. i., Heyrovsky Sq. 2, 162 06 Prague 6, Czech Republic.
2) Institute of Polymer Materials, Friedrich-Alexander-University Erlangen-Nuremberg, Martensstrasse 7, 91058 Erlangen, Germany.
Contacts:
a) Corresponding author:
b)
c)
Abstract:
The influence of a new compatibilization system (mixtures of styrene-butadiene block copolymer (SBS) with ethene-propene random copolymer (EPM)) on morphology and flow properties of polystyrene/polyolefin blends was investigated. The refinement of structure as well as higher values of rheological characteristics and toughness manifested good compatibilization efficiency of mixtures SBS and EPM copolymers in the blends. Morphological study showed a special arrangement of the mixed compatibilizers in a double-layer at the interface, with the SBS copolymer oriented to the polystyrene and EPM copolymer to the polyolefin phase.
Jana Mikesova | Institute of Macromolecular Chemistry | Czech Republic
11:00 – 11:30
ON THE CHARACTERISATION OF THE VOČADLO FLUIDS USING A BACK EXTRUSION TECHNIQUE
Autors:
P. Filip a), J. David b) and R. Pivokonsky c)
Affiliation:
Institute of Hydrodynamics, Acad.Sci.Czech Rep., Pod Patankou 5, 166 12 Prague 6, Czech Republic.
Contacts:
a) Corresponding author:
b)
c)
Abstract:
At present standard rheometers provide sufficiently precise measurements characterising behaviour of non-Newtonian materials. In practice, this accuracy is not always necessary, and the methods providing relatively cheap, fast and sufficient measurements of the rheological characteristics are fully acceptable. Back extrusion – representing one of these methods – is based on plunging of a circular rod into an axisymmetrically located circular cup containing the experimental sample. Formerly this method was successfully applied to power-law, Bingham and Herschel-Bulkley fluids. The aim of this contribution is to present a sufficiently simple user-friendly procedure how to determine the individual rheological parameters appearing in the Vočadlo model (sometimes called Robertson-Stiff one) – yield stress, consistency parameter and flow behaviour index. Good agreement was found between the experimental data of other authors and the proposed procedure.
Petr Filip | Institute of Hydrodynamics | Czech Republic
11:30 – 12:00
Application of AWS viscometry on geological materials
Autor:
Marek Vecer
Affiliation:
Institute of Chemical Processes Fundamentals, Czech Republic.
Abstract:
Flow of microdisperse liquids (suspensions, colloidal emulsions, polymer solutions, etc.) is always accompanied by the Apparent Wall Slip (AWS) effect, caused by interactions between the moving dispersion and a solid surface. In particular, depletion of the disperse phase from a thin layer close to the wall can cause drastic local changes of consistency. This phenomenon is manifested by strongly non-linear velocity profiles close to the wall, with experimentally observed anomalies of flow and convective mass transfer. In the present contribution, quantitative data about fluidity and slip are presented for colloidal suspensions. Both model and real suspensions of various concentrations of solid particles and solvent viscosity has been studied. Several effective viscosity models are employed.
Marek Vecer | Institute of Chemical Processes Fundamentals | Czech Republic
12:00 – 13:30
Lunch & Exhibition
13:30 – 14:00
POLYMER PROCESSING ADDITIVES TO ENHANCE EXTRUSION PROCESSING OF BIMODAL HDPE FOR HIGH PRESSURE PIPE APPLICATIONS
Autor:
J. De Witte
Affiliation:
3M Belgium N.V., Canadastraat 11, B-2070 Zwijndrecht, Belgium.
Contact:
Corresponding author:
Abstract:
The extrusion throughput of several classes of polymers is limited by a processing surface defect known as cyclic melt fracture or “sharkskin”. The surface of the polymer becomes rough, resulting in a change in certain surface properties and gloss. Sharkskin occurs beyond a critical throughput and affects operations such as film blowing, film casting, extrusion blown moulding, pipe extrusion, wire & cable coating extrusions and more recently also wood-plastic composite extrusions. The use of fluoropolymer based polymer processing additives (PPA) to solve problems as melt fracture and die lip build-up has become widespread in the polyolefin extrusion industry. Incorporation of a PPA allows processors to increase throughput, reduce energy consumption and enhance processing quality. PPAs are used to optimise the process conditions in a wide range of applications without having to make compromises on the properties of the final products. The continuing growth in high pressure pipe usage for water and gas transportation, both for new installations as well as for renovation of existing concrete or steel pipe lines, brings new challenges to the resin manufacturer and the pipe producers to fulfil the demanding requirements of the construction industry for these applications. This paper presents some new technical case studies showing how Dynamar™ PPAs can be used specifically for improvement of the rheological behaviour of bimodal HDPE polymers in the extrusion processing of high pressure pipes to achieve benefits in both production efficiency and product quality.
Johan De Witte | 3M Belgium N.V. – Dyneon | Belgium
14:00 – 14:30
SINGLE SCREW DESIGN OPTIMISATION FOR FUEL LINE BARRIER LAYER MATERIAL BASED ON EXTRUSION PROCESS SIMULATION
Autors:
D. Böttner 1, a), J. Vlcek 2, b) and M. Zatloukal 3, c)
Affiliations:
1) TI Automotive (Fuldabrück) GmbH, Industriestraße 1, 34277 Fuldabrück, Germany.
2) Compuplast International, Inc., Nerudova 158, P.O. Box 24, 760 01 Zlín, Czech Republic.
3) Tomas Bata University in Zlín, Polymer Centre, TGM 275, 762 72 Zlín, Czech Republic.
Contacts:
a) Corresponding author:
b)
c)
Abstract:
In this paper analysing and optimising single screw design and extruder setup for an existing high speed series process for multilayer fuel lines is described. An optimised screw design and process parameter setup was developed by using commercial simulation software for the most sensitive material of the multilayer structure, EVOH. The simulation calibration process led to systematic compilation of material and process data. A much better understanding of existing problems like pressure fluctuations and temperature deviations based on the basic theory is given by evaluation of the simulation results and variation of process parameters like compression ratio or temperature setup. The verification of the optimised screw shows an excellent prediction quality of the rpm and melt temperature which were the main optimisation criterions at constant output and end pressure of the extruder.
Dietmar Boettner | TI Automotive | Germany
14:30 – 15:00
CABLE MANUFACTURING: UNDERSTANDING THE RELATIONSHIP BETWEEN MATERIAL AND PROCESS FOR BETTER PRODUCT QUALITY
Autors:
B. Touré a), J. M. Gonnet, M. Veaux and T. Delcourt
Affiliation:
Nexans Research Center, 170, Avenue Jean Jaurès, 69007 Lyon, France.
Contact:
a) Corresponding author:
Abstract:
The relationship between material and process is of big importance in cable manufacturing where filled compounds are used for specific properties of the cable, where production is generally performed at high speed and where the uncontrolled centering of the conductor could be problematic. The specific attention will be paid to the following areas: How fillers can influence product quality? Incidence of the nature of the polymer and the amount of fillers. How to get good centering of conductor on an insulation process? Influence of the die diameter and the position of the tip. Manufacturing a profile at higher speed: influence of the compounds, the temperature and the speed.
Biran Toure | Nexans Research Centre | France
15:00 – 15:30
Refreshment & Exhibition
15:30
End of the conference