* The abstracts are available for each conference contribution when you click on the corresponding title.
July 28, 2015
7:00 – 8:20
Registration
8:20 – 8:30
Welcome
FLOW INSTABILITIES I
(Chairman: Yong Woo Inn)
8:30 – 9:00
Investigations of Slip in Capillary Flow by Laser-Doppler Velocimetry and Their Relations to Melt Fracture
Autor:
Helmut Münstedt
Affiliation:
Institute of Polymer Materials, Friedrich-Alexander University Erlangen-Nürnberg, Martensstr. 7 D-91058 Erlangen, Germany.
Contact:
Corresponding author:
Abstract:
Flow profiles within a slit capillary are measured by laser-Doppler velocimetry. They allow the direct determination of the slip velocity at the wall. It is demonstrated that the flow profile of the melt of a high density polyethylene (HDPE) already shows slip components at small shear rates. At high shear rates the slip is dominant and a plug flow is found. Furthermore, it is shown that the surface irregularity called “shark skin” is generated at the slit exit by the stretching of surface layers at pronounced elongational rates. These elongational rates are due to the differences between the flow velocities at the wall of the slit and those of the extruded strand. It is shown how “shark skin” may be avoided when the elongational rate is reduced by introducing slip of the melt in the slit using special additives.
Helmut Münstedt | Friedrich-Alexander University Erlangen-Nürnberg | Germany
9:00 – 9:30
Biodegradable Polymers: Wall Slip, Melt Fracture, and Processing Aids
Autors:
Norhayani Othman 1, 3, a), Nazbanoo Noroozi 1, b), Bashar Jazrawi 1, c), Parisa Mehrkhodavandi 2, d), Laurel Schafer 2, e) and Savvas George Hatzikiriakos 1, f)
Affiliations:
1) Department of Chemical and Biological Engineering, The University of British Columbia, Vancouver, BC, Canada.
2) Department of Chemistry, The University of British Columbia, Vancouver, BC, Canada.
3) Faculty of Chemical Engineering, Universiti Teknologi Malaysia, Skudai 81310, Johor Bahru Malaysia.
Contacts:
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f) Corresponding author:
Abstract:
The wall slip and melt fracture behaviour of several commercial polylactides (PLAs) and poly(ε-caprolactone), (PCLs) have been investigated. PLAs with molecular weights greater than a certain value were found to slip, with the slip velocity to increase with decrease of molecular weight consistent with wall slip data reported in the literature for other systems. The onset of melt fracture for the high molecular weight PLAs was found to occur at about 0.2 to 0.3 MPa, depending on the geometrical characteristics of the dies and independent of temperature. Similarly, sharkskin and gross melt fracture was observed for the case of PCLs depending on the molecular characteristics of the resins and the geometrical details of the capillary dies. It was also found that the addition of a small amount of PCL (typically 0.5 wt.%) into the PLA and vice versa is effective in eliminating and delaying the onset of melt fracture to higher shear rates in the capillary extrusion of PLA and PCL respectively. This is due to significant interfacial slip that occurs in the presence of PCL or PLA as well as to the immiscibility of the PLA/PCL blend system at all compositions.
Savvas George Hatzikiriakos | The University of British Columbia | Canada
9:30 – 10:00
Cofee break & Exhibition
FLOW INSTABILITIES II
(Chairman: Savvas George Hatzikiriakos)
10:00 – 10:30
Melt Fracture, Wall Slip, and Flow-Induced Fractionation of Bimodal Polyethylenes
Autor:
Yong Woo Inn
Affiliation:
Chevron Phillips Chemical Company LP, Bartlesville Research and Technology Center, Bartlesville, OK 74003-6670, USA.
Contact:
Corresponding author:
Abstract:
The melt fracture and wall slip behaviors of bimodal polyethylene (PE) resins are compared with those of unimodal PE resins. The apparent wall slip is estimated by comparing the flow curves obtained by capillary rheology measurements with the linear viscoelastic data. It is confirmed that the higher content of small chains could cause more wall slip. The unimodal resin with broader molecular weight distribution (MWD) and the bimodal resin with higher content of low molecular weight (MW) component have matte surface roughness on the extrudates at lower stress. It is proposed that the flow-induced fractionation leading to the small chains being more concentrated on the die wall interface could cause the wall slip and unusual melt fracture behaviors in the capillary extrusion.
Yong Woo Inn | Chevron Phillips Chemical Company LP | USA
10:30 – 11:00
Die Drool Phenomenon in Plastics Processing
Autor:
Martin Zatloukal
Affiliation:
Polymer Centre, Faculty of Technology, Tomas Bata University in Zlín, nam. T. G. Masaryka 275, 762 72 Zlin, Czech Republic.
Contact:
Corresponding author:
Abstract:
In the plastics extrusion process, the spontaneous accumulation of molten plastics at the die exit face can take place, which is highly undesirable. This unwanted flow phenomenon is termed as “die drool” and the accumulated material is generally named “drool”. In this work, breakthrough works in the field of die drool research are presented, many ways to suppress it are shown, techniques for its quantitative evaluation and experimental methods for its analytical investigation are introduced, external and internal die drool types are explained and theories of external as well as internal die drool formation mechanism are presented.
Martin Zatloukal | Tomas Bata University in Zlin | Czech Republic
11:00 – 11:30
Slip of Polydisperse Polymers: Molecular Weight Distribution Above and Below the Plane of Slip
Autors:
Seyed Mostafa Sabzevari 1, a), Satu Strandman 2, b) and Paula Marie Wood-Adams 1, c)
Affiliations:
1) Department of Mechanical and Industrial Engineering, Concordia University, Montreal, QC, Canada.
2) Departement de Chimie, Universite ́de Montreal, Montreal, QC, Canada.
Contacts:
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c) Corresponding author:
Abstract:
When strong slip occurs during the drag flow of highly entangled polybutadienes (PBD) in a sliding plate rheometer equipped with stainless steel parallel plates, a thin film of polymer debris remains on the substrate after the slip. This debris is assumed to be formed by the disentanglement process that occurs in strong slip at a distance of about one molecular size from the plate. In order to evaluate the composition of the debris we collected it with tetrahydrofuran and subjected it to gel permeation chromatography. It was found that the molecular weight distribution (MWD) of the debris is significantly different from that of the bulk. Moreover, in mixtures prepared from long and short PBDs with distinctly different molecular weight distributions, the MWD of the debris was found to be richer in low molecular weight components and leaner in the high molecular weight components compared to the bulk. This information is important since it reveals the compositional difference between the bulk and interfacial layer above and below the plane of slip. The difference in MWD is likely a consequence of the strong slip in which some of long chains are pulled away from the surface-adsorbed chains by the flow leaving a debris lean in the high molecular weight component.
Paula Marie Wood-Adams | Concordia University | Canada
11:30 – 12:00
Flow Induced Migration in Polymer Melts – Theory and Simulation
Autors:
John Robert Dorgan a) and Nicholas Andrew Rorrer b)
Affiliation:
Department of Chemical and Biological Engineering, Colorado School of Mines, 1500 Illinois Street, Golden, Colorado 80401, United States.
Contacts:
a) Corresponding author:
b)
Abstract:
Flow induced migration, whereby polymer melts are fractionated by molecular weight across a flow field, represents a significant complication in the processing of polymer melts. Despite its long history, such phenomena remain relatively poorly understood. Here a simple analytical theory is presented which predicts the phenomena based on well-established principles of non-equilibrium thermodynamics. It is unambiguously shown that for purely viscous materials, a gradient in shear rate is needed to drive migration; for purely viscometric flows no migration is expected. Molecular scale simulations of flow migration effects in dense polymer melts are also presented. In shear flow the melts exhibit similar behavior as the quiescent case; a constant shear rate across the gap does not induce chain length based migration. In comparison, parabolic flow causes profound migration for both unentangled and entangled melts. These findings are consistent with the analytical theory. The picture that emerges is consistent with flow induced migration mechanisms predominating over competing chain degradation mechanisms.
John Robert Dorgan | Colorado School of Mines | USA
12:00 – 13:30
Lunch & Exhibition
DEGRADATION AND STABILITY
(Chairman: Alan Jeffrey Giacomin)
13:30 – 14:00
Rheological Characterization of Thermal, Thermo- Oxidative and Photo-Oxidative Degradation of LDPE
Autors:
Víctor Hugo Rolón-Garrido a) and Manfred Hermann Wagner b)
Affiliation:
Chair of Polymer Engineering and Physics, Berlin Institute of Technology (TU Berlin), Fasanenstr. 90, D-10623 Berlin, Germany.
Contacts:
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b)
Abstract:
Rheology has been used to study thermal degradation (V. H. Rolón-Garrido et al., Rheol. Acta 50, 519-535, 2011), thermo-oxidative degradation (V. H. Rolón-Garrido et al., Rheol. Acta 50, 519-535, 2011; V. H. Rolón-Garrido et al., J. Rheol. 57, 105-129, 2013) and photo-oxidative degradation (V. H. Rolón-Garrido and M. H. Wagner, Polym. Degrad. Stab. 99, 136-145, 2014; V. H. Rolón-Garrido and M. H. Wagner, J. Rheol. 58, 199-22 2, 2014; V. H. Rolón-Garrido et al., Polym. Degrad. Stab. 111, 46-54, 2015) of low-density polyethylene (LDPE). This contribution presents the analogies and differences between these types of degradations of LDPE on the linear (by use of van-Gurp Palmen plots) and non-linear viscoelastic properties (by use of the parameters of the MSF model, fmax2 and β), as well as on the failure mode of the samples (through the maximum strain and stress achieved experimentally). In contrast to thermal and thermo-oxidative degradation, the linear viscoelastic properties of photo-oxidated samples were more affected by degradation. In the non-linear regime, for thermal and thermo-oxidative treated samples, the elongational measurements elucidated the role of chain scission and long-chain branching (LCB) formation, while for photo-oxidated LDPE even the competition between chain scission, LCB formation, and gel formation was demonstrated. The failure behavior was found to be determined by a constant maximum strain in thermo-oxidative degradation, if the LDPE has high content in branching points, or in photo-oxidative degraded LDPE, if a considerable portion of gel structure is present. Otherwise, either the maximum strain or stress measured was found to be strain-rate dependent.
Manfred Hermann Wagner / Víctor Hugo Rolón-Garrido | Berlin Institute of Technology (TU Berlin) | Germany
14:00 – 14:30
Effect of Shear Rate on Ethylene/Propylene Copolymers Degradation
Autors:
Ana Vera Machado a) and José António Covas b)
Affiliation:
IPC/I3N – Institute Polymers and Composites, Department of Polymer Engineering University of Minho, Campus de Azurém, 4800-058 Guimarães, Portugal.
Contacts:
a) Corresponding author:
b)
Abstract:
Since rheology deals with the structure/morphology of materials, it can be an important technique to explore thermal degradation of polyolefins. Therefore, this work uses rheology to assess degradation of polyolefins. The effects of polyolefins structure (ethylene/propylene ratio), temperature and shear on the degradation behavior were investigated by dynamic rheological measurement. The results showed that the degree of cross-linking and/or chain scission depends not only on ethylene/propylene ratio but also on temperature and shear. While polypropylene (PP) exhibited chain scission, polyethylene (PE) suffered cross-linking and EPR, depending on the E/P ratio, exhibited a behavior between PP and PE. Moreover, it was found that as the temperature or the E/P ratio increases the level of cross-linking also increases. Cross-linked materials showed the appearance of characteristic second plateau (in G’ vs. ω) at low frequencies while materials that undergone chain scission exhibited deterioration of properties (G’ and η*) over the whole range of frequency.
Ana Vera Machado | University of Minho | Portugal
14:30 – 15:00
Cofee break & Exhibition
DEGRADATION AND FLOW INSTABILITIES
(Chairman: Manfred Hermann Wagner)
15:00 – 15:30
Die Drool and Polymer Degradation
Autors:
Geoffrey Stephen Hoy a), Alan Jeffrey Giacomin b) and Peter Hunter Gilbert c)
Affiliation:
Chemical Engineering Department, Polymers Research Group, Queen’s University, Kingston, Ontario, Canada, K7L 3N6.
Contacts:
a)
b) Corresponding author:
c)
Abstract:
Die drool is an operational problem associated with polymer extrusion. Extrudate collects outside of the die, necessitating periodic disruptions for cleaning. There exists some debate as to the mechanism that produces die drool: stress induced fractionation or thermal degradation. This paper examines the latter. In cohesive failure, a slip discontinuity develops in the velocity profile, where heat is generated by friction. This slip heating can contribute to resin degradation, resulting in lower molecular weight fragments in the die drool. This paper examines the kinetics of this degradation, its influence on die drool rates, and on the resulting polymer concentration profiles in the drool layer and in the bulk.
Alan Jeffrey Giacomin | Queen’s University | Canada
15:30 – 16:00
Weld Lines in Extrusion: Understanding the Role of the Flow Conditions
Autors:
Olga Sousa Carneiro a), Luís Lima Ferrás b), Paulo Teixeira c), Célio Pinto Fernandes d) and João Miguel Nóbrega e)
Affiliation:
IPC/I3N – Institute Polymers and Composites, Department of Polymer Engineering University of Minho, Campus de Azurém, 4800-058 Guimarães, Portugal.
Contacts:
a) Corresponding author:
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Abstract:
This work presents a numerical and experimental study on the flow behavior of a polymer melt around the spider leg of a prototype extrusion die, designed to study the relationship between the thermo-mechanical conditions in which the weld lines are formed and their impact. The numerical simulations will enable to study the influence of the spider leg location on the flow type developed and on the corresponding stress, velocity and pressure fields. Extrusion runs were also performed in the same conditions and the resulting extrudates were mechanically characterized. These two sources of information (numerical and experimental) are complementary and will, therefore, help to better understand the aforementioned relationship. For the numerical simulations we consider that the flow is isothermal and that the polymer melt (a polystyrene) can be modeled adequately by the multimode Giesekus model.
Olga Sousa Carneiro | University of Minho | Portugal
18:30
Conference dinner
July 29, 2015
CONSTITUTIVE EQUATIONS
(Chairman: Vít Průša)
8:00 – 8:30
A Unifying Model for Elongational Flow of Polymer Melts and Solutions Based on the Interchain Tube Pressure Concept
Autors:
Manfred Hermann Wagner a) and Víctor Hugo Rolón-Garrido b)
Affiliation:
Chair of Polymer Engineering and Physics, Berlin Institute of Technology (TU Berlin), Fasanenstr. 90, D-10623 Berlin, Germany.
Contacts:
a) Corresponding author:
b)
Abstract:
An extended interchain tube pressure model for polymer melts and concentrated solutions is presented, based on the idea that the pressures exerted by a polymer chain on the walls of an anisotropic confinement are anisotropic (M. Doi and S. F. Edwards, The Theory of Polymer Dynamics, Oxford University Press, New York, 1986). In a tube model with variable tube diameter, chain stretch and tube diameter reduction are related, and at deformation rates larger than the inverse Rouse time τR, the chain is stretched and its confining tube becomes increasingly anisotropic. Tube diameter reduction leads to an interchain pressure in the lateral direction of the tube, which is proportional to the 3rd power of stretch (G. Marrucci and G. Ianniruberto. Macromolecules 37, 3934-3942, 2004). In the extended interchain tube pressure (EIP) model, it is assumed that chain stretch is balanced by interchain tube pressure in the lateral direction, and by a spring force in the longitudinal direction of the tube, which is linear in stretch. The scaling relations established for the relaxation modulus of concentrated solutions of polystyrene in oligomeric styrene (M. H. Wagner, Rheol. Acta 53, 765-777, 2014, M. H. Wagner, J. Non-Newtonian Fluid Mech. http://dx.doi.org/10.1016/j.jnnfm.2014.09.017, 2014) are applied to the solutions of polystyrene (PS) in diethyl phthalate (DEP) investigated by Bhattacharjee et al. (P. K. Bhattacharjee et al., Macromolecules 35, 10131-10148, 2002) and Acharya et al. (M. V. Acharya et al. AIP Conference Proceedings 1027, 391-393, 2008). The scaling relies on the difference ΔTg between the glass-transition temperatures of the melt and the glass-transition temperatures of the solutions. ΔTg can be inferred from the reported zero-shear viscosities, and the BSW spectra of the solutions are obtained from the BSW spectrum of the reference melt with good accuracy. Predictions of the EIP model are compared to the steady-state elongational viscosity data of PS/DEP solutions. Except for a possible influence of solvent quality, linear and nonlinear viscoelasticity of entangled polystyrene solutions can thus be obtained from the linear-viscoelastic characteristics of a reference polymer melt and the shift of the glass transition temperature between melt and solution.
Manfred Hermann Wagner | Berlin Institute of Technology (TU Berlin) | Germany
8:30 – 9:00
Applicability of the Modified XPP Model to a Description of Flow Behaviour of Polymeric Materials
Autors:
Radek Pivokonsky a), Petr Filip b) and Jana Zelenkova c)
Affiliation:
Institute of Hydrodynamics, Acad. Sci. Czech Rep., Pod Patankou 5, 166 12 Prague, Czech Republic.
Contacts:
a) Corresponding author:
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c)
Abstract:
A 3N-parameter (3 parameters per mode) phenomenological modification of the XPP model for a description of the rheological properties of polymer melts is proposed. The predictive/fitting capabilities of the modified XPP model are compared with the Giesekus, XPP, and modified Leonov models using various polymeric materials in steady shear and uniaxial elongational flows. Its predictability of the rheological properties of the studied materials seems to be very good, including strain hardening in uniaxial elongational flow. Consequently, the GS derivative term was implemented into this modified XPP model. Then the model contains two linear parameters per mode (relaxation time and shear modulus) and two non-linear ones (the fitting parameter simultaneously controlling both strain hardening in elongation flow and shear thinning, and the slip parameter influencing almost solely shear thinning). The efficiency of this model is tested using LDPE and HDPE materials and compared with the modified Leonov model and network-based exponential PTT and PTT-XPP models, both of them containing the GS derivative term.
Radek Pivokonsky | Institute of Hydrodynamics ASCR | Czech Republic
9:00 – 9:30
Implementation of Integral Viscoelastic Constitutive Models in OpenFOAM® Computational Library
Autors:
Manoel Silvino Batalha de Araújo 1, b), Célio Fernandes 2, c), Luís Lima Ferrás 2, d), Željko Tukovic 3, e), Hrvoje Jasak 3, 4, f) and João Miguel Nóbrega 2, a)
Affiliations:
1) Universidade Federal do Pará, Instituto de Ciências Exatas e Naturais, Faculdade de Matemática – 66075-110 – Belem, PA – Brasil.
2) Institute for Polymers and Composites/I3N, University of Minho, Campus of Azurém, 4800-058 Guimarães, Portugal.
3) Faculty of Mechanical Engineering and Naval Architecture, University of Zagreb, Croatia.
4) Wikki Ltd., London, United Kingdom.
Contacts:
a) Corresponding author:
b)
c)
d)
e)
f) ,
Abstract:
This work reports the implementation and verification of a new solver in OpenFOAM® open source computational library, able to cope with integral viscoelastic models based on the integral upper-convected Maxwell model. The code is verified through the comparison of its predictions with analytical solutions and numerical results obtained with the differential upper-convected Maxwell model.
João Miguel Nóbrega | University of Minho | Portugal
9:30 – 10:30
Cofee break & Poster section & Exhibition
Perspectives on Using Implicit Type Constitutive Relations in the Modelling of the Behaviour of Non-Newtonian Fluids
Autors:
Adam Janečka a) and Vít Průša b)
Affiliation:
Faculty of Mathematics and Physics, Charles University in Prague, Sokolovská 83, Praha 8 – Karlín, CZ 186 75, Czech Republic.
Contacts:
a)
b) Corresponding author:
Abstract:
We discuss the benefits of using the so-called implicit type constitutive relations introduced by K. R. Rajagopal, J. Fluid Mech. 550, 243-249 (2006) and K. R. Rajagopal, Appl. Math. 48, 279-319 (2003) in the description of the behaviour of non-Newtonian fluids. In particular, we focus on the benefits of using the implicit type constitutive relations in the mathematical modelling of fluids in which the shear stress/shear rate dependence is given by an S-shaped curve, and in modelling of fluids that exhibit nonzero normal stress differences. We also discuss a thermodynamical framework that allows one to cope with the implicit type constitutive relations.
Vít Průša | Charles University in Prague | Czech Republic
Investigation of Thermal Degradation of Branched Polypropylene via Rheology
Autors:
Jiri Drabek a) and Martin Zatloukal b)
Affiliation:
Polymer Centre, Faculty of Technology, Tomas Bata University in Zlín, nam. T. G. Masaryka 275, 762 72 Zlin, Czech Republic.
Contacts:
a)
b) Corresponding author:
Abstract:
In this work, virgin as well as thermally degraded branched polypropylenes were investigated by using rotational and Sentmanat extensional rheometers. Based on the shear and extensional rheology data it was deduced that both chain scission and chain branching takes place during thermal degradation of the tested polypropylene. It was found that simple phenomenological constitutive equations such as Generalized Newtonian law and modified White Metzner model can be used to describe the measured steady state shear and uniaxial extensional viscosity data as well as for the simple quantification of the extensional strain hardening via their model parameters.
Jiri Drabek | Tomas Bata University in Zlin | Czech Republic
Oscillation Rheometry – Method for Processing Stability Testing of High Sensitive Polymers
Autors:
Roderik Plavec a), Ján Bočkaj b), Zuzana Vanovčanová c), Leona Kaliňáková d), Jozef Feranc e), Miroslava Mikušová f), Katarína Tomanová g), Dávid Šariský h) and Pavol Alexy i)
Affiliation:
Institute of Natural and Synthetic Polymers, Faculty of Chemical and Food Technology, Slovak University of Technology, Radlinského 9, 812 37 Bratislava, Slovak Republic.
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i) Corresponding author:
Abstract:
This work introduces the oscillation rheometry as a method for determination of processing stability of polymers, which are high sensitive to degradation during melt processing. The oscillation rheometry was found as a simple and rapid method which could indicate the first stages of degradation process. Changes in relative complex viscosity were taken as indicator of processing stability. It was shown that changes in relative complex viscosity reflect changes in molecular weight of degraded polymer very well.
Pavol Alexy | Slovak University of Technology | Slovak Republic
Comparison between Extensional Rheological Properties of Low Density Polyethylene Melt in SER and RME Rheometric Systems
Autors:
Esmaeil Narimissa a), Víctor Hugo Rolón-Garrido b) and Manfred Hermann Wagner c)
Affiliation:
Polymer Engineering/Polymer Physics, Berlin Institute of Technology (TU Berlin), Fasanenstrasse 90, 10623 Berlin, Germany.
Contacts:
a) Corresponding author:
b)
c)
Abstract:
Precise evaluation and notional prediction of extensional rheological behaviour of polymeric melts and solutions are of significant importance in polymer industry. This is evident in the well documentation of the dominance of elongational deformation of polymeric systems in processes such as melt spinning, blow moulding, biaxial stretching of extruded sheets, etc. The relevant commercial extensional rheometers thus far discussed in the literature are RME and SER. This research, for the first time, compares the extensional viscosity measurements of low density polyethylene at 140, 150, and 170 °C through RME and SER devices. Despite the observed similarities found in this comparative investigation, the main difference was laid in maximum Hencky strain, strain hardening viscosity, and the variation of those rheological properties with testing temperature of the samples.
Esmaeil Narimissa | Berlin Institute of Technology (TU Berlin) | Germany
Effect of Viscoelastic Stress State at Die Exit on Extrusion Film Casting Process: Theoretical Study
Autors:
Tomas Barborik a) and Martin Zatloukal b)
Affiliation:
Polymer Centre, Faculty of Technology, Tomas Bata University in Zlin, nam. T. G. Masaryka 275, 762 72 Zlin, Czech Republic.
Contacts:
a)
b) Corresponding author:
Abstract:
In this work, viscoelastic, isothermal extrusion film casting modeling utilizing 1D membrane model and modified Leonov model was performed in order to understand the role of viscoelastic stress state at the die exit on the polymer melt film stretching in the post die area. Experimental data for LDPE and theoretical predictions based on the eXtended Pom-Pom (XPP) model taken from the open literature were used for the validation purposes. It was found that predicting capabilities of 1D membrane model utilizing XPP and modified Leonov model are comparable for the given processing conditions and material. Consequent theoretical parametric study revealed that increase in the viscoelastic stress state at the die exit, characterized as the ratio of second and first normal stress differences, -N2/N1, leads to increase in neck-in phenomenon. This suggests that specific attention should be paid to optimization of the extrusion die design in order to stabilize polymer melt film stretching in the post die area.
Tomas Barborik | Tomas Bata University in Zlin | Czech Republic
Rheology of Multiphase Polymer Systems using Novel „Melt Rigidity” Evaluation Approach
Autor:
Milan Kracalik
Affiliation:
Johannes Kepler University Linz, Institute of Polymer Science, Altenberger Str. 69, 4040 Linz, Austria.
Contact:
Corresponding author:
Abstract:
Multiphase polymer systems like blends, composites and nanocomposites exhibit complex rheological behaviour due to physical and also possibly chemical interactions between individual phases. Up to now, rheology of heterogeneous polymer systems has been usually described by evaluation of viscosity curve (shear thinning phenomenon), storage modulus curve (formation of secondary plateau) or plotting information about damping behaviour (e.g. Van Gurp-Palmen-plot). On the contrary to evaluation of damping behaviour, „melt rigidity“ approach has been introduced for description of physical network of rigid particles in polymer matrix as relation of ∫G’/∫G” over specific frequency range. This approach has been experimentally proved for polymer nanocomposites in order to compare shear flow characteristics with elongational flow field. In this contribution, LDPE-clay nanocomposites with different dispersion grades (physical networks) have been prepared and characterized by both conventional as well as novel „melt rigidity“ approach.
Milan Kracalik | Johannes Kepler University Linz | Austria
Rheological Investigation of Highly Filled Polymers: Effect of Molecular Weight
Autors:
Eva Hnatkova 1, 2, a), Berenika Hausnerova 1, 2, b), Andrew Hales 3, c), Lukas Jiranek 4, d) and Juan Miguel Alcon Vera 5, e)
Affiliations:
1) Department of Production Engineering, Faculty of Technology, Tomas Bata University in Zlín, nám. T. G. Masaryka 5555, 760 01 Zlín, Czech Republic.
2) Centre of Polymer Systems, University Institute, Tomas Bata University in Zlín, Nad Ovčírnou 3685, 760 01 Zlín, Czech Republic.
3) The University of Sheffield, Department of Materials Science and Engineering, Sir Robert Hadfield Building, Mappin Street, Sheffield, S1 3JD, United Kingdom.
4) Beckett MIM, Tinsley Industrial Park Shepcote Way Sheffield, S9 1TH, United Kingdom.
5) Universidad de Castilla-La Mancha, ETSII-UCLM, Avda. Camilo José Cela s/n, E-13071 Ciudad Real, Spain.
Contacts:
a) Corresponding author:
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Abstract:
The paper deals with rheological properties of highly filled polymers used in powder injection molding. Within the experimental framework seven PIM feedstocks based on superalloy Inconel 718 powder were prepared. Each feedstock contains the fixed amount of powder loading and the same composition of binder system consisting of three components: polyethylene glycol (PEG) differing in molecular weight, poly (methyl methacrylate) (PMMA) and stearic acid (SA). The aim is to investigate the influence of PEG’s molecular weight on the flow properties of feedstocks. Non-Newtonian indices, representing the shear rate sensitivity of the feedstocks, are obtained from a polynomial fit, and found to vary within measured shear rates range from 0.2 to 0.8. Temperature effect is considered via activation energies, showing decreasing trend with increasing of molecular weight of PEG (except of feedstock containing 1,500 g.mol-1 PEG).
Eva Hnatkova | Tomas Bata University in Zlin | Czech Republic
Shear-Induced Structure Evolution of Carbon Nanotubes Dispersions in Polyacrylonitrile–Dimethylsulfoxide Solution
Autors:
Evgeny Karpushkin 1, a), Maria Lapshina 2, b) and Vladimir Sergeyev 1, c)
Affiliations:
1) Department of Chemistry, Lomonosov Moscow State University, Leninskie Gory 1–3, Moscow, 119991 Russia.
2) Department of Materials Science, Lomonosov Moscow State University, Leninskie Gory 1–73, Moscow, 119991 Russia.
Contacts:
a) Corresponding author:
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Abstract:
Rheological behavior of carbon nanotubes finely dispersed in polyacrylonitrile–dimethylsulfoxide solution has been studied as function of the applied pre-shear stress and discussed in view of possible structural changes induced by the pre-shearing of the samples. The observed effects can be ascribed to a combination of internal processes involving alignment and association of the macromolecules as well as orientation and association of carbon nanotubes. The effects caused by the macromolecules alignment and association are mainly observed at low concentration of the filler and at higher shear stress, whereas the processes involving carbon nanotubes reorganization are mainly observed at the higher filler content and at low pre-shear stress.
Evgeny Karpushkin | Lomonosov Moscow State University | Russia
Comparison of Electrorheological Characteristics Obtained in Two Geometrical Arrangements: Parallel Plates and Concentric Cylinders
Autors:
Petra Peer 1, a), Petr Filip 1, b), Martin Stenicka 2, c) and Vladimir Pavlinek 2, d)
Affiliations:
1) Institute of Hydrodynamics, Acad. Sci. Czech Rep., Pod Patankou 5, 166 12 Prague, Czech Republic.
2) Centre of Polymer Systems, University Institute, Tomas Bata University in Zlín, Nad Ovčírnou 3685, 760 01 Zlín, Czech Republic.
Contacts:
a) Corresponding author:
b)
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Abstract:
The electrorheological characteristics of suspensions of PANI powders suspended in silicone oil measured by a rotational rheometer Physica MCR 501 (Anton Paar Co.) are compared for two different geometrical arrangements – parallel plates and concentric cylinders. The individual differences in the results of the measured parameters are discussed.
Petra Peer | Institute of Hydrodynamics ASCR | Czech Republic
Squeezing Flow of Collagen Solution – Mathematical Model of Shear and Elastic Behavior
Autors:
Aleš Landfeld 1, a), Rudolf Žitný 2, b), Jan Skočilas 2, c), Jaromír Štancl 2, d), Martin Dostál 2, e) and Milan Houška 1, f)
Affiliations:
1) Food Research Institute Prague, Radiová 7, 102 31 Prague 10, Czech Republic.
2) Faculty of Mechanical Engineering, Technická 4, 166 29 Prague 6, Czech Republic.
Contacts:
a)
b)
c)
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f) Corresponding author:
Abstract:
This contribution deals with the problem of the squeezing flow of highly concentrated collagen solution (7%). The sample of collagen is compressed between two parallel disks of the texture analyzer instrument TA-XT2i. The bottom disk is fixed and the upper one is approaching at a constant velocity. During experiment the force acting on the moving plate is measured accurately. Total force – deformation dependence data sets were applied for evaluation of parameters of mathematical model having independent parameters for shear and elongation deformation regimes. Because lubricated Teflon foils are attached to the both plates a partial wall slip on plates is considered in the developed mathematical model assuming prevalence of the elongation flow contribution.
Jan Skočilas | Czech Technical University in Prague | Czech Republic
Preparation of Bacterial Cellulose Based Hydrogels and Their Viscoelastic Behavior
Autors:
Rushita Shah 1, 2, a), Radek Vyroubal 1, b), Haojei Fei 1, 2, c), Nabanita Saha 1, 2, d), Takeshi Kitano 1, 2, e) and Petr Saha 1, 2, f)
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.
Contacts:
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b)
c)
d) Corresponding author:
e)
f)
Abstract:
Bacterial cellulose (BC) based hydrogels have been prepared in blended with carboxymethylcellulose and polyvinyl pyrrolidone by using heat treatment. The properties of BC-CMC and BC-PVP hydrogels were compared with pure BC, CMC and PVP hydrogels. These hydrogels were investigated by measuring their structural, morphological and viscoelastic properties. Through the morphological images, alignment of the porous flake like structures could be seen clearly within the inter-polymeric network of the hydrogels. Also, the detail structure analysis of the polymers blended during the hydrogel formation confirms their interactions with each other were studied. Further, the viscoelastic behavior of all the hydrogels in terms of elastic and viscous property was studied. It is observed that at 1% strain, including CMC and PVP hydrogels, all the BC based hydrogels exhibited the linear trend throughout. Also the elastic nature of the material remains high compared to viscous nature. Moreover, the changes could be noticed in case of blended polymer based hydrogels. The values of complex viscosity (η*) decreases with increase in angular frequency within the range of ω = 0.1-100 rad.s-1.
Rushita Shah | Tomas Bata University in Zlin | Czech Republic
The Effect of Combination Electrospun and Meltblown Filtration Materials on Their Filtration Efficiency
Autors:
Dusan Kimmer 1, a), Ivo Vincent 1, b), Wannes Sambaer 2, c), Martin Zatloukal 2, 3, d) and Jakub Ondracek 4, e)
Affiliations:
1) SPUR a.s., trida Tomase Bati 299, Louky, 763 02 Zlin, Czech Republic.
2) Polymer Centre, Faculty of Technology, Tomas Bata University in Zlín, nám. 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.
4) Institute of Chemical Process Fundamentals of the CAS, v. v. i., Rozvojová 135/1, 165 02 Praha 6, Czech Republic.
Contacts:
a) Corresponding author:
b)
c)
d)
e)
Abstract:
Filtration materials prepared by combination of electrospun nanofibers and meltblown microfibers (both fixed on polypropylene spunbond supports) were characterized from the point of view of their filtration efficiency in ultrafine particles separation. Compared are electrospun and meltblown structures and their combinations characterized by means of digital image analysis properly. Layer of electrospun nanofibers in MB air filtration materials can ensure improvement of filtration efficiencies for ultrafine particles separation.
Dusan Kimmer | SPUR a.s. | Czech Republic
INTRODUCTION OF NOVEL RHEOLOGICAL TOOLS
(Chairman: Paula Marie Wood-Adams)
10:30 – 11:00
Following Curing Reactions with Rheometry and Simultaneous FTIR-Spectroscopy
Autor:
Jan Philip Plog
Affiliations:
Thermo Fisher Scientific, 76227 Karlsruhe, Germany.
Resultec, 89171 Illerkirchberg, Germany.
Contact:
Corresponding author:
Abstract:
In this article a new and unique combination of a rheometer and an FTIR-spectrometer is presented. The so-called Rheonaut module allows the coupling of the Thermo Scientific HAAKE MARS rheometer platform with an FTIR-spectrometer. With this set-up, samples can be characterized rheologically using cone/plate or plate/plate geometries while IR-spectra are being recorded simultaneously. To test this new concept, thermally induced polymerization and cross-linking reactions have been followed with the combination of HAAKE MARS and the Rheonaut module. Depending on the chemical nature of the components involved, the disappearance of the starting material’s reactive group and/or the appearance of chemical groups, which are characteristic for the product can be seen and correlated with the development of the mechanical properties. Details of this unique instrument set-up as well as selected results will be presented.
Jan Philip Plog | Thermo Fisher Scientific | Germany
11:00 – 11:30
Orthogonal Superposition (OSP) Rheology as a Tool to Study Structures in Complex Fluids
Autors:
Michael Schopferer a), Carlos A. Gracia-Fernández b), Aadil Elmoumni c), Aly Franck d) and Bharath Rajaram e)
Affiliation:
TA Instruments, New Castle, DE 19720, USA.
Contacts:
a) Corresponding author:
b)
c)
d)
e)
Abstract:
Many simultaneous techniques are being used to follow structural changes in materials as a result of an imposed shear deformation. Orthogonal superposition, first mentioned by Philippoff in 1934 (W. Philippoff, Physik-Z. 35, 884, 900 (1934)) is a mechanical technique and uses a small amplitude oscillation shear applied orthogonal to a shear flow. In contrast to parallel superposition, the flow fields are not coupled and the orthogonal storage and loss moduli only measure the effect of shear on the microstructure. OSP has been implemented in the ARES-G2 rheometer by modifying the transducer to apply a small oscillatory displacement in normal direction, while the actuator of the rheometer performs the transient or oscillatory rotational shear deformation. The normal force transducer in this case applies the orthogonal deformation and records the force. The dynamic moduli, complex viscosity and phase are determined using the embedded instrument correlation technique. The flow cell used to apply the rotational and linear axial shear simultaneously is a modified double wall cylinder with an opening at the bottom to avoid annular pumping and windows at the top to eliminate surface tension effects. With the OSP option the rheometer is capable to perform the following additional test modes:
- Small (linear) strain orthogonal oscillation superposed on rotational steady shear
- (2D-SAOS) Small (linear) strain orthogonal oscillation superposed on rotational oscillation at the same frequency with varying amplitude ratio between axial and rotational oscillation shear
- Standalone small axial displacement oscillations
Electro-Rheological (ER) fluids are suspensions of extremely fine non-conducting particles in an electrically insulating fluid. They show dramatic and reversible rheological changes when the electric field is applied. The ARES-G2 OSP functionality is used to characterize the structural changes of ER fluids when different voltages and shearing conditions are applied. Particularly, 2D-SAOS gives more insight in the structure formation and provides a tool to quantify it.
Michael Schopferer | TA Instruments | USA
11:30 – 12:00
Novel Technologies for Rheological Investigations
Autor:
Loredana Mirela Völker-Pop
Affiliation:
Anton Paar Germany GmbH, Hellmuth-Hirth-Str. 6 73760 Ostfildern, Germany.
Contact:
Corresponding author: loredana.voelker-pop@anton- paar.com
Abstract:
Complex fluids are essential components for different applications of chemical processes, in life science or various industries. Technological progresses have led to new types of materials with improved properties, designed to fit special applications. This automatically implies that both, instruments and testing methods have to fulfill the qualitative standards imposed by material development. Due to new features, larger parameter ranges and high measurement accuracy the capabilities of the Anton Paar MCR rheometers have been extended, enabling new possibilities for modern research. The MCR rheometers fit to a wide range of modular accessories tailored to specific rheological requirements, in a temperature range from -150 °C to 1000 °C, from low-viscosity liquids to highly elastic solids, from traditional rheological tests to DMTA (dynamic mechanical thermal analysis) measurements, interfacial or extensional rheology, tack and tensile testing, measurements under humidity control. Microstructural changes as well as the behaviour of samples under various external influences, e.g. pressure, electric and magnetic fields and UV-light can be studied. The scientific knowhow accumulated over the years and close cooperation with R&D departments and universities made possible the development of new measuring techniques and analysis methods, specially tailored for various materials such as polymer solutions, melts, gel-like systems, suspensions, emulsions etc. In our presentation novel technologies together with relevant application examples will be discussed.
Loredana Mirela Völker-Pop | Anton Paar Germany GmbH | Germany
13:00 – 13:30
Lunch & Exhibition
ELONGATIONAL RHEOLOGY
(Chairman: Helmut Münstedt)
13:30 – 14:00
Necking Failure and Physical Rupture of a Molten Low Density Polyethylene (LDPE) Sample Undergoing Uniaxial Extension
Autors:
Zdeněk Starý 1, a) and Teodor Burghelea 2, b)
Affiliations:
1) Institute of Polymer Materials, Friedrich-Alexander University, Martensstrasse 7, D-91058 Erlangen, Germany.
2) LUNAM Université, Université de Nantes, CNRS, Laboratoire de Thermocinétique, UMR 6607, La Chantrerie, Rue Christian Pauc, B.P. 50609, F-44306 Nantes Cedex 3, France.
Contacts:
a)
b) Corresponding author:
Abstract:
A detailed experimental investigation of the deformation regimes, failure and physical rupture of a low density polyethylene (LDPE) sample undergoing extension at a constant nominal rate is presented. By combining integral measurements of the tensile forces and of the tensile stresses with the in-situ visualization of the sample within a wide range of Weissenberg numbers Wi, three distinct deformation regimes are observed. At low Wi (Wi < 10), a viscous (flowing) deformation regime characterized by a single local maximum of the tensile force (engineering stress) related to the onset of a necking instability is observed. The rupture of the sample within this regime occurs via a ductile mechanism. For intermediate values of the Weissenberg number, 10 ≤ Wi ≤ 200, a transitional deformation regime characterized by a competition between the failure behavior (via primary necking) and the stabilizing strain hardening (elastic) effects is observed. The physical rupture of the sample occurs via the emergence of secondary necks. As the Weissenberg number is further increased, Wi > 200, the strain hardening eventually wins over the necking instability and this ultimately modifies the dynamics of the physical rupture of the sample.
Teodor Burghelea | Universite de Nantes | France
14:00 – 14:30
Electrical Conductivity and Rheology of Carbon Black Composites under Elongation
Autor:
Zdeněk Starý
Affiliation:
Institute of Polymer Materials, Friedrich-Alexander-University Erlangen-Nuremberg, Martensstr. 7, 91058 Erlangen, Germany.
Contact:
Corresponding author:
Abstract:
Electrical properties of conductive polymer composites are governed by filler particle structures which are formed in the material during the mixing. Therefore, knowledge of the behavior of conductive particle structures under defined conditions of deformation is necessary to produce materials with balanced electrical and rheological properties. Whereas the electrical conductivity evolution under shear can be nowadays studied even with the commercial rheometers, the investigations under elongation were not performed up to now. In this work simultaneous electrical and rheological measurements in elongation on polystyrene/carbon black composites are introduced. Such kind of experiment can help in understanding the relationships between processing conditions and properties of conductive polymer composites.
Zdeněk Starý | Friedrich-Alexander University Erlangen-Nürnberg | Germany
14:30 – 15:00
Refreshment & Exhibition
FLOW MODELING
(Chairman: João Miguel Nóbrega)
15:00 – 15:30
Application of Computer Simulations: Molecular Insight into Electrospinning
Autors:
Filip Moucka a), Jan Jirsak b) and Ivo Nezbeda c)
Affiliation:
Faculty of Science, J. E. Purkinje University, České mládeže 8, 40096 Usti n. L., Czech Republic.
Contacts:
a)
b)
c) Corresponding author:
Abstract:
Needleless electrospinning is a modern electrodeposition method (patented in 2005) used to efficiently produce non-woven tissues (NanoSpider™ technology) with variety of applications. From the physical point of view it is the problem of free surface of a solution, typically composed of water, ions, and polymer molecules, exposed to a strong electric field. The external field disturbs the surface giving rise to the Taylor cones and the subsequent eruption of matter in the form of a spray or jet or stream. These phenomena can be explained using the phenomenological electro-hydrodynamics focussing, in general, on the competition between the surface tension and electric forces. Although there is a vast literature dealing with this problem, yet “… a complete understanding of the mechanism remains to be elucidated and the factors that govern fibre formation are not well understood” [C.S. Kong, W.S. Yoo, N.G. Jo, H.S. Kim, J. Macromol. Sci. Phys. 49, 122-131 (2010)]. There is a number of both macroscopic (thermodynamic) and microscopic (e.i., molecular) parameters that affect the electrospinning process. Molecular simulations (Monte Carlo or molecular dynamics methodology) provide the tool which allow many parameters (experimental variables) to be explored and which may provide insight into the process and mechanisms driving its performance. Electrospinning is a fast and non-equilibrium process and the primary question to be asked is to what extent molecular simulations may be able to imitate it at all. We have identified three regions of the process that may be amenable to simulation studies and considered appropriate corresponding methodologies. Proceeding step by step, we started with pure water adding then gradually salt (NaCl) to examine its effect at the qualitative level. Finally, polymer molecules were added to examine feasibility of such simulations. All the performed simulations, viewed at this stage necessarily as a feasibility study, confirmed that molecular simulations can be used to study in detail the process of electrospinning and provide also quantitative results in terms of relations between various physical quantities. As a first such result, we obtained the relation between the strength of the electric field and ion’s concentration separating jetting from spraying. Simulations with various polymers are underway with the ultimate goal to relate the solution composition and polymer type to the properties of the produced fibers. Preliminary results will be reported along with open questions and discussion on continuing research.
Ivo Nezbeda | J. E. Purkinje University | Czech Republic
15:30 – 16:00
3D modeling of Polyurethane Electrospun Nanofiber Membrane Clogging During Air Filtration
Autors:
Wannes Sambaer 1, a), Martin Zatloukal 1, b), Dusan Kimmer 2, c)
Affiliations:
1) Polymer Centre, Faculty of Technology, Tomas Bata University in Zlin, TGM 275, 762 72 Zlin, Czech Republic.
2) SPUR a.s., trida Tomase Bati 299, Louky, 763 02 Zlin, Czech Republic.
Contacts:
a)
b) Corresponding author:
c)
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-particle and particle-fiber friction coefficients on filter clogging and basic filter characteristics.
Wannes Sambaer | Tomas Bata University in Zlin | Czech Republic
16:00
End of the conference