* The abstracts are available for each conference contribution when you click on the corresponding title.
July 30, 2019
7:00 – 8:20
Registration
8:20 – 8:30
Welcome
APPLIED RHEOLOGY I
(Chairman: José Covas)
8:30 – 9:00
Elastic Behavior and Processing of Polymer Melts
Autors:
Helmut Münstedt 1, a)
Affiliations:
1) Institute of Polymer Materials, Friedrich-Alexander-University Erlangen-Nürnberg, Martensstr. 7 D-91058 Erlangen.
Contacts:
a) Corresponding author:
Abstract:
Whereas the influence of viscous properties of a polymer melt on some aspects of processing has widely been reported in the literature, investigations with respect to elastic properties are rare. In this paper effects of the elastic behavior on processing and those of processing on molecular orientation and recoverable strain are presented. As elastic property the role of extrudate swell in its many facets is discussed. Experiments on cast film extrusion are described and their results discussed as a function of the Deborah number, which is often used as a quantity for the elasticity at short processing times. Film contours and resonance frequencies are presented in detail. With respect to the influence of processing on properties of manufactured items results from the literature are discussed, which show that one has to distinguish between effects on the orientation of molecule segments and on the recoverable strain. The role of non-uniform distributions of the recoverable strain within a manufactured sample for its properties is shortly addressed.
Helmut Münstedt | Friedrich-Alexander University Erlangen-Nürnberg | Germany
9:00 – 9:30
Influence of Long Chain Branching on Fiber Diameter Distribution for Polypropylene Nonwovens Produced by Melt Blown Process
Autors:
Martin Zatloukal a) and Jiri Drabek b)
Affiliations:
Polymer Centre, Faculty of Technology, Tomas Bata University in Zlín, Vavrečkova 275, 760 01 Zlín, Czech Republic.
Contacts:
a) Corresponding author:
b)
Abstract:
In this work, linear polypropylene (L-PP) and long-chain branched polypropylene miscible blend (LCB-PP), both having comparable weight average molecular weight (76 – 78 kg/mol), zero-shear viscosity (22.8 – 24.51 Pa·s at 230 °C) and polydispersity (4.41 – 4.50) were used to produce nonwovens via melt blown technology at constant temperature (270 °C) and two different die-to-collector distances (200 mm and 500 mm) in order to understand role of long chain branching on the fiber diameter distribution. Melt elasticity was evaluated via macroscopic relaxation time determined by shear viscosity data fitting by Cross and Carreau-Yasuda models and the longest relaxation time obtained by fitting small amplitude oscillatory shear data with a generalized Maxwell model. Extensional rheology was assessed by the strain rate dependent uniaxial extensional viscosity (estimated from the entrance pressure drop using the Gibson method) as well as through the infinite shear to zero-shear viscosity ratio, η∞/η0, (obtained directly from the measured experimental data), which is proportional to the maximum normalized extensional viscosity at very high extensional strain rates, ηE,∞/(3η0). Basic morphological characteristics of produced nonwoven samples have been determined using digital image analysis of SEM images considering three different magnifications to capture nanofibers as well as microfibers. Obtained results suggests, that utilization of low molecular weight and branched polymers can stabilize production of polymeric nanofibers and microfibers through melt blown technology considerably.
Martin Zatloukal | Tomas Bata University in Zlin | Czech Republic
9:30 – 10:00
Cofee break & Exhibition
APPLIED RHEOLOGY II
(Chairman: Helmut Münstedt)
10:00 – 10:30
Strain-Hardening Behavior in Elongational Viscosity of Polyolefin Blends
Autors:
Masayuki Yamaguchi 1, a), Yoko Fujii 1, b) and Panitha Phulkerd 1, c)
Affiliations:
1) Materials Chemistry Area, Japan Advanced Institute of Science and Technology 1-1 Asahidai, Nomi, Ishikawa 923-1292 JAPAN.
Contacts:
a) Corresponding author:
b)
c)
Abstract:
Growth curves of uniaxial elongational viscosity for binary blends composed of two types of polyolefins were studied. For miscible blends of linear-low density polyethylene (LLDPE) and low-density polyethylene (LDPE), the strain-hardening behavior for the blends is more pronounced than that for pure LDPE, when the shear viscosity of LLDPE is higher than that of LDPE. This is attributed to the prolonged relaxation of long-chain-branched molecules in LDPE owing to the decrease in the constraint release. Furthermore, the strain-hardening behavior is also detected in the sea-island phase-separated blend in which linear polyolefin such as isotactic polypropylene (PP) is a matrix and a branched polyolefin like LDPE is dispersion. As increasing the elongational strain, the droplets in the blends are deformed with the matrix, and eventually become rigid fibers due to the strain-hardening behavior of the droplets. Consequently, the matrix located between the fibrous droplets has to be deformed greatly during elongational flow. This excess localized deformation is responsible for the strain-hardening in the transient elongational viscosity for the immiscible blends.
Masayuki Yamaguchi | Japan Advanced Institute of Science and Technology | Japan
10:30 – 11:00
Effect of Flow Field on Structure and Properties for Polycarbonate Blends
Autors:
Masayuki Yamaguchi 1, a) and Takumi Sako 1, b)
Affiliations:
1) Materials Chemistry Area, Japan Advanced Institute of Science and Technology 1-1 Asahidai, Nomi, Ishikawa 923-1292 JAPAN.
Contacts:
a) Corresponding author:
b)
Abstract:
Flow-induced segregation and phase-mixing behaviors of polymer blends comprising polycarbonate (PC) and another polymer with low molecular weight, such as poly(methyl methacrylate) (PMMA) and polystyrene (PS), are studied. Although PMMA with low molecular weight is miscible with PC, the PMMA fraction in an injection-molded plate is found to be rich at the surface, suggesting that PMMA is segregated to the surface region under pressure-driven flow in the mold. The high concentration of the PMMA fraction at surface will provide enhanced surface hardness of a product. Furthermore, the PS addition is found to decrease the apparent shear viscosity greatly especially in the high shear rate region at capillary extrusion, which will be responsible for a long spiral flow length at injection-molding. The decrease in the shear viscosity is attributed to the flow-induced phase-mixing, which occurs only in the surface region.
Masayuki Yamaguchi | Japan Advanced Institute of Science and Technology | Japan
11:00 – 11:30
In-Process Rheological Measurements During the Manufacture of Multiphase Polymer Systems
Autors:
José A. Covas 1, a), Paulo F. Teixeira 1, b) and Loic Hilliou 1, c)
Affiliations:
1) IPC/I3N – University of Minho, Campus de Azurém 4800-058 Guimarães, Portugal.
Contacts:
a) Corresponding author:
b)
c)
Abstract:
The properties of multiphase systems (e.g., immiscible and compatibilized polymer blends, nanocomposites) depend on the characteristics of the components, on their concentration, on the interfacial adhesion and on the resulting morphology. In turn, the latter is influenced by the thermomechanical environment created during the manufacture of these systems, often by twin screw extrusion. Since the rheological behaviour of a material is sensitive to its morphology, this work provides an overview of in-process rheometry solutions working along the barrel and/or at the die, thus contributing for a better understanding and a more efficient manufacturing of this type of materials.
José Covas | University of Minho | Portugal
11:30 – 12:00
3D-Printing Quality in Relation to Melt Flow and Fusion Behavior of Polymer Materials
Autors:
Dietmar Auhl a), Falk Rohnstock b), Oliver Löschke c), Konstanze Schäfer d), Peng Wang e) and Manfred H. Wagner f)
Affiliations:
Department of Polymer Materials and Technologies, Berlin University of Technology, Ernst-Reuter-Platz 1, D-10587 Berlin.
Contacts:
a) Corresponding author:
b) Corresponding author: f.rohnstock@tu-berlin.
c)
d)
e)
f)
Abstract:
Full fusion and layer contact are essential for the mechanical, but also optical quality of 3D-printed parts. A comprehensive study on relations of 3D-printing quality to melt flow and fusion behavior is presented for a wide range of thermoplastic polymer materials. We investigated the influence of polymer structure and chain length as well as processing temperature, which largely determine material viscosity and surface tension. Furthermore, the influence of particle or layer dimensions is investigated. Comparisons of experimental and simulated data using well-established models and sets of parameters allow drawing valuable conclusions for optimizations of 3D-printing conditions and product quality.
Dietmar Auhl | Berlin Institute of Technology (TU Berlin) | Germany
12:00 – 13:30
Lunch & Exhibition
NOVEL RHEOLOGICAL TECHNIQUES I
(Chairman: Paula Marie Wood-Adams)
13:30 – 14:00
Rheological Methods for the Characterization of Viscoelasticity in Industrial Polymers
Autors:
Vitor C. Barroso a), Katrin Hofstadler b), Bernhard Knogler c) and Lukas Sobczak d)
Affiliations:
Borealis Polyolefine GmbH, Sankt-Peter-Strasse 25, 4021 Linz, Austria.
Contacts:
a)
Abstract:
Industrial polymers, unlike well-defined model polymer systems synthesised by very specific chemical techniques, possess wide-ranging structural details and several levels of molecular complexity. This makes the characterisation of such industrial polymers somewhat elusive since their ensemble behaviour is made up of more complex and heterogeneous interactions, as compared to well-defined model polymer systems. This complexity is reflected on the chemical composition distribution, which is ultimately one of the main sources of the different behaviours displayed during polymer processing sequences. During such sequences, the polymer is subject to different velocity, pressure and temperature profiles which make up for different responses in terms of their time-dependent (viscoelastic) behaviour. Of crucial relevance for any kind of polymer processing sequence are therefore the rheological properties of the molten polymers, which as well derive from their chemical composition distribution. The proper characterisation of the viscoelastic properties is therefore a challenge, since rheological methods able to capture the behaviour for wide-ranging time scales will always have to suffer from some limitation, whether from an operational perspective or from a physico-chemical perspective. The potential of rheological techniques to differentiate between different types of polymer structures is well displayed on the generally clear distinction between the behaviour of linear and branched polymers. However, the image gets many times blurred between the somewhat similar effects of branching and broad molar mass distribution. This has been a challenge in the rheological community and is of special relevance for the industrial rheologist, especially when assisting in the development of new products. In this communication, a critical overview is taken on different aspects for distinguishing among complex industrial polymers using rheological techniques, as well as on discussing new approaches for characterising their viscoelastic properties. Test methods which try to simultaneously extract information for both long-term as well as short-term rheological behaviour will be discussed, resorting to the characterisation of different molecular structures of commercial industrial polyolefins.
Vitor Barroso | Borealis Polyolefine GmbH | Austria
14:00 – 14:30
Advanced Rheological Characterisation for Thermal Sensitive Materials Using Shear Heating Device
Autors:
Frederik Desplentere 1, a), S. Deceur 1, b) and M. Vandaele 1, c)
Affiliations:
1) ProPoLiS research group, KU Leuven Bruges Campus Spoorwegstraat 12, B-8200 Bruges, Belgium.
Contacts:
a) Corresponding author:
b)
c)
Abstract:
In predictive engineering for polymer processes, the rheological data is the most important data to end up with good prediction of processing parameters. In case of materials which are highly temperature sensitive and have a low bulk density, one has to be sure that the obtained data is representative for the future processing. One should avoid applying unrealistic conditions to the material causing unacceptable degradation of the material. To cover this issue, an advanced capillary rheometer has been developed which is able to heat the material to be tested in an advanced way. Simply conductive heating is combined with some controllable shearing resulting in measurement times which are only some minutes. Using a standard capillary rheometer, measurement times are most often more than ten minutes. The main disadvantage of this fast measuring technique is the sample temperature. To illustrate the good functioning of this equipment together with the validity of the results, a comparative reference measurement is set up for a non thermal sensitive material. This approach also allows to investigate the influence of the different settings influencing the shearing within the sample preparation for the shear viscosity measurement. Based on these promising results, the advanced rheometer can be used to perform accurate measurements for thermal sensitive materials as there are PVC. PVC is typically provided in powder form as raw material. While processing this material, it is highly sensitive for slip at the wall. Some promising results are obtained using this equipment.
Frederik Desplentere | KU Leuven | Belgium
14:30 – 15:00
Cofee break & Exhibition
NOVEL RHEOLOGICAL TECHNIQUES II
(Chairman: Donggang Yao)
15:00 – 15:30
Continuum Mechanics of Shear Stress Growth
Autors:
Chaimongkol Saengow 1, a) and Alan Jeffrey Giacomin 2, b)
Affiliations:
1) Polymers Research Group, Chemical Engineering Department, Queen’s University, Kingston, ON, CANADA K7L 3N6.
2) Mechanical and Materials Engineering Department Queen’s University, Kingston, ON, CANADA K7L 3N6.
Contacts:
a)
b) Corresponding author:
Abstract:
One good way to explore fluid microstructure experimentally is to suddenly subject the fluid to a large steady shearing deformation, and to then observe the evolving stress response. If the steady shear rate is high enough, the shear stress and also the normal stress differences can, overshoot, and then, they can even undershoot. We call such responses nonlinear, and this experiment shear stress growth. This work discusses exact analytical solutions for interpreting measured nonlinear shear stress growth responses from the Oldroyd 8-constant constitutive framework. Specifically, we explore the effect of η∞ on stress growth material functions using the special case of the corotational Jeffreys fluid. Using the Johnson-Segalman fluid, we also explore the effect of non-affine deformation. Lastly, we explore the role played by three nonlinear Oldroyd parameters (μ0, ν1, ν2).
Alan Jeffrey Giacomin | Queen’s University | Canada
15:30 – 16:00
Interdiffusion Dynamics at the Interface between two Polystyrenes with Different Molecular Weight Probed by a Rheological Tool
Autors:
Wissam Nakhle 1, a), Marie-Claude Heuzey 1, b) and Paula M. Wood-Adams 2, c)
Affiliations:
1) Département du Génie Chimique, Ecole Polytechnique, Montréal, QC, Canada.
2) Department of Mechanical, Industrial and Aerospace Engineering, Concordia University, Montreal, QC, Canada.
Contacts:
a)
b)
c) Corresponding author:
Abstract:
Interdiffusion between two molten polystyrenes is studied under small amplitude oscillatory shear (SAOS). Our rheological technique exploits differences in molecular weights and thus in viscosity, to investigate interdiffusion dynamics. The torque is measured during radial interdiffusion in a concentric binary sample, at constant temperature and frequency. We have previously confirmed that our rheological technique can be used to characterize solvent diffusion in molten polymers. Our results confirm that the interdiffusion rate is significantly increased due to oscillatory motion.
Paula Marie Wood-Adams | Concordia University | Canada
18:30
Conference dinner
July 31, 2019
CONSTITUTIVE EQUATIONS
(Chairman: Jeffrey Giacomin)
8:00 – 8:30
On Diffusive Variants of Some Classical Viscoelastic Rate-Type Models
Autors:
Mark Dostalík 1, a), Vít Průša 1, b) and Tomáš Skřivan 2, c)
Affiliations:
1) Faculty of Mathematics and Physics, Charles University, Sokolovská 83, Praha 8 – Karlín, CZ 186 75, Czech Republic.
2) Institute of Science and Technology Austria, Am Campus 1, Klosterneuburg, A 3400, Austria.
Contacts:
a)
b) Corresponding author:
c)
Abstract:
We present a thermodynamically based approach to the design of models for viscoelastic fluids with stress diffusion effect. In particular, we show how to add a stress diffusion term to some standard viscoelastic rate-type models (Giesekus, FENE-P, Johnson–Segalman, Phan-Thien–Tanner and Bautista–Manero–Puig) so that the resulting models with the added stress diffusion term are thermodynamically consistent in the sense that they obey the first and the second law of thermodynamics. We point out the potential applications of the provided thermodynamical background in the study of flows of fluids described by the proposed models.
Vít Průša | Charles University in Prague | Czech Republic
8:30 – 9:00
A Framework for Nonlinear Viscoelasticity on the Basis of Logarithmic Strain and Projected Velocity Gradient
Autors:
Donggang Yao 1, a)
Affiliations:
1) School of Materials Science and Engineering, Georgia Institute of Technology, Atlanta, GA 30332, USA.
Contacts:
a) Corresponding author:
Abstract:
Most existing nonlinear viscoelastic models are founded on the Finger tensor and its evolution during deformation and flow. In this paper, a new framework for nonlinear viscoelasticity on the basis of a projected velocity gradient tensor is presented. The pairing of the logarithmic strain tensor with the projected velocity gradient tensor is considered the cornerstone of the proposed formulation. The resulting linear relation for strain evolution in affine deformation provides a facile passage to connect small deformation mechanics with large deformation mechanics. Accordingly, proven linear viscoelastic models may now be extended to large deformation. Another salient feature is that the deformation is decoupled into stretching and rotation and each of them has its own evolution equation. The relaxation process is considered coaxial, whereas rotational retardation is included in the formulation to tackle with shear-related rotational softening. In this way, the similarity and difference between rotational deformation and coaxial deformation are explicitly explored. Strain shape functions are added to the linear version of the model to render more realistic nonlinear effects. The overall framework uses three elements for model formulation, namely, a stretch evolution equation, a rotation evolution equation, and a stress law. Example models are provided to illustrate the proper combination of these elements for creation of useful models. A particular model with a fractional relaxation process is used for model testing against typical observations in simple shear. With five model parameters (one for fractionality, two for linear viscoelasticity, one for straining, and the last one for rotation) is able to fit startup shear viscosity of a polystyrene solution in high accuracy. With additional understanding of the role of entropic strain in the relaxation process, simple and unified constitutive equations for modeling general 3D viscoelastic deformation and flow may be developed.
Donggang Yao | School of Materials Science & Engineering, Georgia Institute of Technology | USA
9:00 – 10:30
Cofee break & Poster section & Exhibition
Effect of Carbon Nanotube Addition on Molecular Orientation of Polyethylene
Autors:
Riho Nishikawa 1, a) and Masayuki Yamaguchi 1, b)
Affiliations:
1) Materials Chemistry Area, Japan Advanced Institute of Science and Technology 1-1 Asahidai, Nomi, Ishikawa 923-1292 Japan.
Contacts:
a)
b) Corresponding author:
Abstract:
Structure and properties for strands extruded from a capillary rheometer were studied using polyethylene (PE) containing carbon nanotubes (CNTs). We found that the CNT addition surprisingly enhances the chain orientation of PE. The oriented CNTs greatly accelerate the flow-induced crystallization of PE. These findings demonstrate that it will be a new method to enhance the rigidity of PE effectively.
Riho Nishikawa | Japan Advanced Institute of Science and Technology | Japan
Effect of Metal Salt Incorporation on Structure and Properties for Poly(Vinyl Alcohol)
Autors:
Riza Saari 1, a), Ryosuke Tsuyuguchi 1, b) and Masayuki Yamaguchi 1, c)
Affiliations:
1) Materials Chemistry Area, Japan Advanced Institute of Science and Technology, 1-1 Asahidai, Nomi, Ishikawa 923-1292, Japan.
Contacts:
a)
b)
c) Corresponding author:
Abstract:
Recently, the incorporation of a specific salt has been studied intensively to modify the rheological properties of a polymer. In this work, lithium bromide as a metal salt was incorporated into an aqueous solution of poly(vinyl alcohol) (PVA). It was found that the LiBr addition decreases the oscillatory modulus. Besides, the solution also shows lower shear viscosity. Moreover, the film obtained by the evaporation of water showed low glass transition temperature, which is attributed to the weak hydrogen bonding in PVA chains by the ion-dipole interaction with lithium cation.
Riza Saari | Japan Advanced Institute of Science and Technology | Japan
Study on Viscoelastic Properties of Phase-Separated Hydrogels by Time-Temperature Superposition Principle
Autors:
Jiri Smilek 1, a), Martin Kadlec 1, b) and Miloslav Pekar 1, c)
Affiliations:
1) Brno University of Technology, Faculty of Chemistry, Materials Research Centre, Purkynova 464/118, CZ-612 00 Brno, Czech Republic.
Contacts:
a) Corresponding author:
b)
c)
Abstract:
Time-temperature superposition principle has been utilized for the study on viscoelastic properties of phase-separated hydrogels. Hydrogels were prepared by interactions of biopolymers (negatively charged hyaluronan or positively charged diethylaminoethyl-dextran) with oppositely charged surface active agents (Septonex or Sodium dodecyl sulfate). By using the time-temperature superposition principle, the viscoelastic properties of these hydrogels have been studied over a large frequency range in comparison with routine macro-rheological approach. The results from time-temperature superposition principle are in good agreement with preliminary micro-rheological approach (dynamic light scattering technique).
Jiri Smilek | Brno University of Technology | Czech Republic
Nanostructures for Air Filtration. Filtration Properties in Range of Maximum Penetrating Particle Sizes
Autors:
Dusan Kimmer 1, 2, a), Ivo Vincent 1, b), Miroslava Kovarova 1, 2, c) and Lenka Lovecka 1, d)
Affiliations:
1) Centre of Polymer Systems, University Institute, Tomas Bata University, Trida Tomase Bati 5678, 760 01 Zlin, Czech Republic.
2) SPUR, a.s., Trida Tomase Bati 299, Louky, 763 02 Zlin, Czech Republic.
Contacts:
a) Corresponding author:
b)
c)
d)
Abstract:
End user customers and legislation of European countries require to classify the air filtration materials for ultra-fine particles separation in range of maximum penetrating particle size (MPPS). The filtration properties of nanostructured materials based on various polymers at comparable conditions (the same pressure drops) have been evaluated.
Dusan Kimmer | SPUR a.s. | Czech Republic
Electrospinning of Poly(ethylene oxide) Solutions – Quantitative Relations between Mean Nanofibre Diameter, Concentration, Molecular Weight, and Viscosity
Autors:
Petr Filip 1, a) and Petra Peer 1, b)
Affiliations:
1) Institute of Hydrodynamics of the Czech Academy of Sciences, 166 12 Prague 6, Czech Republic.
Contacts:
a) Corresponding author:
b)
Abstract:
The process of electrospinning was applied to solutions of poly(ethylene oxide) (PEO) in distilled water. An increase of mean nanofibre diameter with polymer molecular weight (4 different PEO) and polymer concentration (concentrations chosen with respect to spinnability) was expressed by a simple relationship quantifying this dependence within an experimental error. Further, another relationship was proposed for expressing shear viscosity of the entry polymer solution through corresponding molecular weight and concentration. The results show a possibility to prepare PEO nanofibrous mats with prescribed mean nanofibre diameter.
Petra Peer | Institute of Hydrodynamics ASCR | Czech Republic
Approximate Functions Relating Specific Viscosity of PEO in DMSO vs. Concentration Respecting Intrinsic Viscosity for Low Concentrations
Autors:
Jana Zelenkova 1, a) and Petr Filip 1, b)
Affiliations:
1) Institute of Hydrodynamics, Czech Academy of Sciences, Pod Patankou 5, 166 12 Prague, Czech Republic.
Contacts:
a) Corresponding author:
b)
Abstract:
The plots relating specific viscosity of a solution of poly(ethylene oxide) (PEO) in dimethyl sulfoxide (DMSO) with the corresponding PEO concentration can be seemingly approximated by various functions depending whether the normal, semi-log or log-log coordinates are used. However, these approximations should comply with the physical background of their courses, namely with the values of intrinsic viscosities if concentration of PEO in DMSO is tending to zero. To this aim a procedure of evaluating intrinsic viscosity is proposed and the corresponding approximate functions are selected.
Jana Zelenkova | Institute of Hydrodynamics ASCR | Czech Republic
Wall Slip of Highly Filled Powder Injection Moulding Compounds in Dependence on Capillary Die Geometry
Autors:
Petr Filip 1, a), Berenika Hausnerova 2, 3, b), Daniel Sanetrnik 2, 3, c) and Eva Hnatkova 2, d)
Affiliations:
1) Institute of Hydrodynamics, Czech Academy of Sciences, Pod Patankou 5, 166 12 Prague, Czech Republic.
2) Dept. of Production Engineering, Faculty of Technology, Tomas Bata University in Zlin, nam. T. G. Masaryka 5555, 760 01 Zlin, Czech Republic.
3) Centre of Polymer Systems, University Institute, Tomas Bata University in Zlin, Tr. T. Bati 5678, 760 01 Zlin, Czech Republic.
Contacts:
a) Corresponding author:
b)
c)
d)
Abstract:
The feedstocks used in Powder Injection Moulding (PIM) are formed by solid particles incorporated into a binder with presence of surfactant enabling manufacturing of highly concentrated suspensions. Relatively even distribution of particles is violated in the close vicinity of the walls. A thin layer adjacent to the walls is pre-dominantly occupied by the binder only and at the interface wall-binder so-called wall slip occurs. Success and acceptance of an injection moulding step in PIM process primarily subjects to this wall slip phenomenon. The wall slip was qualitatively and quantitatively measured using a capillary rheometer equipped with the dies of different entrance angles. It was proved that this differentness has a significant impact on an appearance of wall slip (its intensity). Using four PIM feedstocks reliable slip velocity values of highly filled compounds were obtained for conical dies contrasting to the results with flat dies used in the majority of studies.
Petr Filip | Institute of Hydrodynamics ASCR | Czech Republic
Measuring Techniques of Rheological Properties of Rubber Blends from Industry
Autors:
Martina Lopatková 1, a), Jozef Feranc 1, b), Pavol Alexy 1, c), Ivan Hudec 1, d) and Jozef Preťo 2, e)
Affiliations:
1) Institute of Natural and Synthetic Polymers, Slovak University of Technology, Radlinského 9, 812 37 Bratislava, Slovak Republic.
2) Vipo, a.s.Generála Slobodu 1069/4, 968 01 Partizánske, Slovak Republic.
Contacts:
a) Corresponding author:
b)
c)
d)
e)
Abstract:
Currently, process of extrusion and injection molding goes to the foreground also in the case of rubber blends. This is the reason to know complex rheological characteristic of processed system. Measuring the rheological properties using rheometers provides valuable information about the behavior of the system. The presented work is focused on the comparison of measuring techniques, which are mainly used to know complex rheological properties. We made our research on commercial rubber blends based on NR and EPDM with sulphur vulcanisation system. As a measuring device we used oscillatory rheometer RPA 2000 and measurements were realised by strain sweep at different temperatures. As second measuring device the capillary rheometer Gӧttfert RG 75 was used. In this case measurements were performed using capillaries with different ratio of length to diameter and also at various temperatures. As last measuring device was used rheological extrusion die, but only for NR tested blend. By this work it is confirmed that every used rheometer to determine rheological properties of tested blends has advantages and also disadvantages. And in generally is very important to take into consider specific features of elastomeric materials.
Patrik Macúrik | Slovak University of Technology | Slovak Republic
Rheological Characterization of Starch-based Biodegradable Polymer Blends
Autors:
Martina Nevoralová 1, a), Aleksandra Ujčić 1, b), Yadu Nath Vakkipurath Kodakkadan 1, c) and Zdeněk Starý 1, d)
Affiliations:
1) Institute of Macromolecular Chemistry, Academy of Sciences of the Czech Republic, Heyrovsky Sq. 2, 162 06 Prague 6, Czech Republic.
Contacts:
a) Corresponding author:
b)
c)
d)
Abstract:
Starch-based polymer blends are often investigated materials that attract great attention due to their disposition to combine advantageous properties of their components and ability to create materials with controlled biodegradation rate. In this contribution the rheological characterization of plasticized starch blended with biodegradable polyester poly (ε-caprolactone) was carried out. For preparation of thermoplastic starch-based blends three different types of starches (wheat, corn and tapioca) were used. Two-step preparation process consisting of solution casting and melt mixing was performed and their rheological and thermomechanical behavior was analyzed. Moreover, morphological study on prepared blends was performed. Since the final properties of polymer blends depend directly on blend composition, the adjusting of the material components concentrations and using distinct processing procedures led to materials with various final morphologies and rheological properties as well. Different rheological behavior in the case of TPS (tapioca)/PCL blends compared to wheat or corn starch blended with PCL was observed. Whereas the latter two blends, as well as their neat starch components, exhibited gel-like behavior over the entire measured temperature range, tapioca starch/PCL blends behave as liquids at processing temperatures. The rheology findings about tapioca starch and its blends with polycaprolactone could be advantageously used for preparation of new starch-based polymer materials with controlled biodegradation and enhanced processability.
Martina Nevoralová | Institute of Macromolecular Chemistry ASCR | Czech Republic
Historical Notes on Flow Visualization in Polymer Melt Processing
Autors:
Jan Musil 1, a) and Martin Zatloukal 1, b)
Affiliations:
1) Polymer Centre, Faculty of Technology, Tomas Bata University in Zlín, Vavrečkova 275, 760 01, Zlín, Czech Republic.
Contacts:
a)
b) Corresponding author:
Abstract:
Flow visualization is commonly used technique in fluid mechanics to get qualitative or quantitative information about flow patterns. Many different visualization techniques have been until now developed. Due to high temperatures and pressures inside processing tools, only four of them, namely dye adding, particle tracking velocimetry, laser-Doppler velocimetry and flow induced birefringence can be used in polymer melt extrusion. In this paper, some interesting historical notes of these methods are presented and their first applications in polymer melt extrusion are shortly introduced.
Jan Musil | Tomas Bata University in Zlin | Czech Republic
Effect of Molecular Weight and Extensional Rheology on Melt Blown Process Stability for Linear Isotactic Polypropylenes
Autors:
Jiri Drabek a) and Martin Zatloukal b)
Affiliations:
Polymer Centre, Faculty of Technology, Tomas Bata University in Zlín, Vavrečkova 275, 760 01, Zlín, Czech Republic.
Contacts:
a)
b) Corresponding author:
Abstract:
Two linear isotactic polypropylenes with different molecular weight have been used to produce nonwovens via melt blown technology in order to understand role of molecular weight and extensional rheology on fiber diameter distribution. Extensional rheology was assessed by the strain rate dependent uniaxial extensional viscosity (estimated from the entrance pressure drop using the Gibson method) as well as through infinite shear to zero-shear viscosity ratio η∞/η0 (obtained directly from the shear viscosity data measured in a very wide shear rate range), which was shown to be related with temperature and basic molecular characteristics of given polymers via a simple equation. This allowed us to determine η∞/η0 ratio for additional nine polypropylene melt blown nonwovens with known weight average molecular weight and coefficient of fiber diameter variation, taken from the open literature. Obtained results indicates that firstly, an increase in the molecular weight decreases η∞/η0 as well as maximum attainable normalized extensional viscosity ηE,∞/3η0 and secondly, there exists optimum η∞/η0 ratio, at which the coefficient of fiber diameter variation is minimal.
Jiri Drabek | Tomas Bata University in Zlin | Czech Republic
The Effect of Heat Transfer Coefficient on Crystalline Phase Development During Production of Casted Film
Autors:
Tomas Barborik 1, a) and Martin Zatloukal 1, b)
Affiliations:
1) Polymer Centre, Faculty of Technology, Tomas Bata University in Zlín, Vavreckova 275, 760 01 Zlin, Czech Republic.
Contacts:
a)
b) Corresponding author:
Abstract:
In this study, the stable numerical scheme has been developed for non-isothermal 1.5D film casting model of Silagy et al. (Polym Eng Sci 36:2614-2625, 1996) utilizing viscoelastic modified Leonov model as the constitutive equation and energy equation coupled with crystallization kinetics of semicrystalline polymers considering actual temperature as well as a cooling rate. In the proposed model, forced and natural convection together with a heat radiation emitting from the film surface is considered to model the heat transfer. Model has been successfully validated on the experimental data for linear isotactic polypropylene taken from the open literature. In this work, effect of the forced convection on the neck in phenomenon (unwanted film width shrinkage during stretching in the post die area) and crystalline phase development during a flat film production was systematically investigated. It is believed that the utilized numerical model together with suggested stable numerical scheme as well as obtained research results can help to more thoroughly understand the processing window for production of flat porous membranes from linear iPP considerably.
Tomas Barborik | Tomas Bata University in Zlin | Czech Republic
Mixing of a Viscoplastic Fluid in an In-Line Mixer
Autors:
Mehmet Ayas 1, a), Jan Skocilas 1, b) and Tomas Jirout 1, c)
Affiliations:
1) Czech Technical University in Prague, Process Engineering Department, 16636 Prague 6, Czech Republic.
Contacts:
a) Corresponding author:
b)
c)
Abstract:
In this study, power consumption and design parameters of a newly designed in-line rotor stator-mixer were investigated particularly for inelastic non-Newtonian fluids. The power consumption of the mixer was measured experimentally using by viscoplastic fluids under the laminar flow case. Then obtained experimental data has been validated by means of numerical methods. It has been shown that experimentally and numerically deduced power-draw values are in a good agreement. Finally, numerically obtained velocity and shear rate profiles within the mixing heads were examined for the three rotational speed of the impellers.
Mehmet Ayas | Czech Technical University in Prague | Czech Republic
Surface Tension Measurement: Attempt to Combine Pendant Drop and Deformed Drop Retraction Methods
Autors:
Josef Jůza 1, a)
Affiliations:
1) Institute of Macromolecular Chemistry of the Czech Academy of Sciences, Heyrovského nám. 2, CZ 162 06 Praha 6, Czech Republic.
Contacts:
a) Corresponding author:
Abstract:
The deformed drop retraction method of boundary tension measurement is based on evaluation of ellipsoid droplet relaxation published by Luciani and Utracki. The pendant drop method is based on evaluation of equilibrium drop shape; when it is applied to viscous liquids, drop shape equilibrates during a certain time similarly as for ellipsoid droplets. This text presents an attempt to apply deformed drop retraction procedure to pendant drop in order to obtain alternative boundary tension estimate. However, the results for testing sample strongly differ from correct surface tensions. The usage of formula for ellipsoid relaxation is a weak point of the estimate presented. The challenge remaining for the future is to describe the relaxation of pendant drop.
Josef Jůza | Institute of Macromolecular Chemistry ASCR | Czech Republic
Different Approaches for Calculation of Cumulative Storage Factor as Novel Parameter for Analysis of Reinforcement in Complex Polymer Nanocomposites
Autors:
Milan Kracalik 1, a)
Affiliations:
1) Johannes Kepler University Linz, Institute of Polymer Science, Altenberger Str. 69, 4040 Linz, Austria.
Contacts:
a) Corresponding author:
Abstract:
Polymer nanocomposites exhibit complex rheological behaviour due to physical and also sometimes chemical interactions between individual components. So far, rheology of polymer nanocomposites has been usually described by evaluation of viscosity curve (shear thinning), storage modulus curve (secondary plateau) or plotting information about dumping behaviour (e.g. Van Gurp-Palmen-plot, Cole-Cole plot). On the contrary to evaluation of damping behaviour, values of cot δ were calculated and called as „storage factor“, analogically to commonly used loss factor. Then values of storage factor were integrated over specific frequency range and called as “cumulative storage factor”. In this contribution, LDPE-ZnO-clay nanocomposites with different dispersion quality (physical networks) have been prepared and characterized by both conventional as well as novel analysis approach.
Milan Kracalik | Johannes Kepler University Linz | Austria
INTRODUCTION OF NOVEL RHEOLOGICAL TOOLS
(Chairman: Roland Kádár)
10:30 – 11:00
Combined rheo-Raman Analysis: Correlating Viscoelastic Behavior with Chemical Structure
Autors:
David A. Bohnsack 1), Bharath Rajaram 1), Lukas Schwab 2, a) and Jennifer Ramirez 3)
Affiliations:
1) TA Instruments – Waters LLC, New Castle, DE 19720, United States.
2) Waters GmbH, TA Instruments, Eschborn, 65760, Germany.
3) Thermo Fisher Scientific, Madison, WI 53711, United States.
Contacts:
a) Corresponding author:
Abstract:
Rheology offers powerful methods for studying a material’s response to shear deformation and changes in environmental conditions. In addition to bulk rheology measurements, there is often a strong desire to explore the relationship between the sample microstructure, chemistry, and the observed mechanical response. Of these, structure visualization through microscopy and scattering techniques is well established in literature. In this study, we present a new rheo-Raman setup that permits chemical structure characterization during rheological measurements. Raman spectroscopy provides critical information about molecular structure and bonding and can elucidate intermolecular interactions of pure components and mixtures. Details are provided for a turnkey system that integrates a commercially available rheometer (Discovery Series HR-3, TA Instruments) with a Raman spectrometer (iXR, Thermo Fisher Scientific). The setup offers temperature control and ensures Class I laser safety through appropriate safety interlocks. In one case of a commercial cosmetic lotion, the temperature dependent decrease in viscosity directly correlates with changes in the C-C and C-H stretching modes that are sensitive to conformational disorder. The results highlight the importance of hyphenated rheometric techniques to fully understand the origins of material viscoelasticity.
Lukas Schwab | Waters GmbH, UB TA Instruments | Germany
11:00 – 11:30
Processing Studies on Rubber Mixtures with Different Types of Carbon Black by Extrusion with Torque Rheometer Method
Autors:
Ansgar Frendel 1, a)
Affiliations:
1) Thermo Fisher Scientific, Germany.
Contacts:
a) Corresponding author:
Abstract:
Extrusion tests with a torque rheometer system are carried out with three different test procedures. Die swell, profile extrusion with a Garvey die according to ASTM D2230 and measurement of shear viscosity with a slit capillary die are presented. Results are compared and the test procedures evaluated regarding time efficiency and ease of use.
Ansgar Frendel | Thermo Fisher Scientific | Germany
11:30 – 12:00
The New Anton Paar MCR 702 MultiDrive – the Versatile Platform for Rheology and Dynamic Mechanical Analysis (DMA)
Autors:
Michal Bartik 1, a)
Affiliations:
1) Anton Paar Czech Republic s.r.o. Strakonická 3309/2e, 150 00, Praha, Czech Republic.
Contacts:
a) Corresponding author:
Abstract:
The new MCR 702 MultiDrive is a dynamic mechanical analyzer based on the renowned MCR rheometer technology. Equipped with two rotational motors and one linear motor, the rheometer features full range of dynamic mechanical analysis capabilities for materials – especially polymers ranging from solid state to liquid state. MCR 702 MultiDrive is a multipurpose platform for DMA and standard rheology tests as well. The device combines completely new linear motor with the renowned EC motor technology (electronically commutated motor). This state-of-the-art linear motor makes it possible to perform DMA in bending, tension, and compression as well as thermomechanical analysis (TMA) with one instrument.
Michal Bartik | Anton Paar | Czech Republic
12:00 – 13:30
Lunch & Exhibition
RHEOLOGY OF POLYMER BLENDS AND COMPOSITES
(Chairman: Frederik Desplentere)
13:30 – 14:00
Evidence of Percolated Network at the Linear – Nonlinear Transition in Oscillatory Shear
Autors:
Karolina Gaska 1, a) and Roland Kádár 1, b)
Affiliations:
1) Chalmers University of Technology, Department of Industrial and Materials Science, Division of Engineering Materials, SE-412 96 Gothenburg, Sweden.
Contacts:
a)
b) Corresponding author:
Abstract:
In this publication we review evidence for the detection of a percolated network in polymer nanocomposites at the linear – nonlinear transition in oscillatory shear tests. Two types of nanocomposites based on branched polymers as matrix are compared: a low density polyethylene (LDPE) and graphite nanoplatelets (GnP) as filler and a poly(ethylenebutyl acrylate) (EBA) containing graphite nanoplatelets and carbon black (CB). Oscillatory shear tests were analyzed in the framework of Fourier-transform rheology and Tschebyshev polynomial decomposition. For both nanocomposites, in the vicinity of the electrical percolation threshold, i.e. the formation of a continuous filler network, a distinct region is evidence at the transition linear – nonlinear transition in the strain dependent third relative higher harmonics of the shear stress Fourier spectra. The region can be characterized by different strain amplitude dependence that could be related to the specific filler morphologies, however, further investigations are required to assess the factors that influence the linear – nonlinear transition region in polymer nanocomposites.
Roland Kádár | Chalmers University of Technology | Sweden
14:00 – 14:30
Rheology and Structure of Immiscible Polymer Blends Filled with Carbon Black
Autors:
Zdeněk Starý 1, a), Martina Nevoralová 1, b) and Valentina Dragčević 1, c)
Affiliations:
1) Institute of Macromolecular Chemistry, Academy of Sciences of the Czech Republic, Heyrovsky Sq. 2, 162 06 Prague 6, Czech Republic.
Contacts:
a) Corresponding author:
b)
c)
Abstract:
In this contribution immiscible polystyrene/polymethylmethacrylate (PS/PMMA) blends filled with carbon black (CB) are investigated in a broad composition range. In these blends carbon black is localized preferentially in polystyrene phase. The influence of carbon black on blends phase structure is evaluated and consequently rheology and electrical conductivity is discussed. Pronounced differences in the morphology of unfilled and filled blends were observed in cases, in which PS phase containing CB forms a minor phase. Dispersed morphology with spherical particles and sharp interfaces turned by addition of 3 vol.% of CB into partially co-continuous morphology with irregular domain shapes. This morphology change was detected even in blends with PS content as low as 10 vol.%. The rheology of the blends was largely influenced by the addition of CB in the systems with PS matrix.
Zdeněk Starý | Institute of Macromolecular Chemistry ASCR | Czech Republic
14:30 – 15:00
Refreshment & End of the conference