* The abstracts are available for each conference contribution when you click on the corresponding title.
July 30, 2025
8:00 – 8:50
Registration
8:50 – 9:00
Welcome
FLOW INSTABILITIES
(Chairman: Manfred Wilhelm)
9:00 – 9:30
Die Lip Buildup and Polymer Rotarance Theory
Autors:
Mona A. Kanso 1, a), Alan Jeffrey Giacomin 2, 3, b), Jan Musil 4, c) and Martin Zatloukal 4, d)
Affiliations:
1) Chemical Engineering Department, Massachusetts Institute of Technology, Cambridge 02139, USA.
2) Mechanical Engineering Department, University of Nevada, Reno, Nevada 89557-0312, USA.
3) State Key Laboratory for Turbulence and Complex Systems, Peking University, Beijing, CHINA.
4) Department of Polymer Engineering, Faculty of Technology, Tomas Bata University in Zlín, Vavrečkova 5669, 760 01 Zlín, Czech Republic.
Contacts:
a)
b) Corresponding author:
c)
d)
Abstract:
Die drool is the unwanted accumulation of material spilling onto the open faces of an extrusion die. In this paper, we explore the intriguing roles of subtle batch to batch variations in nonlinear viscoelasticity and molecular structure on the dimensionless buildup. Specifically, we view the behaviors of high and low dimensionless buildup resin batches through the lens of sudden inception of steady shear flow, both measured and predicted by rigid bead-rod theory. We find that the high drool rate high-density polyethylene film resin exhibits higher shear stress upon sudden inception of steady shear flow than its low drool counterpart. We further find that both high-density polyethylene film resins, examined through the lens of rotarance theory, behave as suspensions of multi-bead rods (also called shish kebabs). Both high-density polyethylene film resins exhibit the same longest relaxation time, the same macromolecular moment ratios, and differ only in their Weissenberg numbers, and thus, in their amounts of nonlinear viscoelasticity.
Alan Jeffrey Giacomin | University of Nevada | USA
9:30 – 10:00
Processing Aids in Eliminating Melt Fracture
Autors:
Xiaohan Jia 1, a), Zeinab Mousavi 1, b), Antonios K Doufas 2, c) and Savvas G. Hatzikiriakos 1, d)
Affiliations:
1) Department of Chemical and Biological Engineering, The University of British Columbia, Vancouver, BC V6T 1Z3, Canada.
2) Sabic Corporate Technology Center at King Abdullah University of Science & Technology, Thuwal, 23955, Saudi Arabia.
Contacts:
a)
b)
c)
d) Corresponding author:
Abstract:
This study presents a comprehensive experimental protocol to evaluate the effectiveness of a polymer processing aid (PPA) in eliminating melt fracture of metallocene linear-low density polyethylene (m-LLDPE) using capillary rheometry. Results show that increasing the temperature or the PPA concentration helps eliminating melt fracture. Increasing the amount of used PPA causes the polymer to slip more and thus decreases significantly the encountered stresses during flow.
Savvas George Hatzikiriakos | The University of British Columbia | Canada
10:00 – 10:30
Coffee break & Exhibition
INDUSTRIAL RHEOLOGY AND PROCESSING
(Chairman: João Miguel Nóbrega)
10:30 – 11:00
How can simulation help in understanding of “peculiarities” in the extrusion process
Autors:
Jiri Vlcek 1, a) and John Perdikoulias 2, b)
Affiliations:
1) Compuplast Software, Zlin, Czech Republic.
2) Compuplast Canada, Toronto, Canada.
Contacts:
a)
b) jp@ compuplast.biz
Abstract:
This presentation shows how the simulation can help in understanding the extrusion process. There are shown several examples from extrusion where the simulation explained hardly understandable material behavior.
The first example is from flat film coextrusion where a certain interface shape on the final film is desired. It is shown how the simulation can be useful in the equipment design and how the process of the design and tuning up can be accelerated by the simulation.
The second example is from extruder design. Usually, screws in medical applications do not have any extra features in design but there is a lot of problems with material degradation. There will be shown how a proper screw for medical application based on some common criteria and simulation should look like.
Probably every screw designer believes that he understands the material behavior in a Maddock or Eagan mixing element. Some experiments performed in Japan showed that the situation is not so simple and the material behavior in the mixing element was unexpected. The flow had to be simulated to explain the observations.
Screw wear is an eternal problem in extruder design, mainly for screws used in a grooved barrel extruder. The simulation indicates that the problem is not in screw design but in the barrel design.
The material viscosity depends, sometimes a lot, on the temperature. Because of this to know the right temperature is very important. But to know the right temperature, there is needed simulation and for the simulation there are needed proper boundary condition. In this example there will be shown how the boundary conditions can change substantially the results of the simulation and because of this an evaluation of the equipment and material behavior.
Jiri Vlcek | Compuplast Software | Czech Republic
11:00 – 11:30
Understanding Flow Instabilities in Multilayer Film Manufacturing
Autors:
Karen Xiao 1) and John Perdikoulias 2)
Affiliations:
1) Macro Engineering & Technology Inc., Mississauga, Ontario, Canada.
2) Compuplast North America, Mississauga, Ontario, Canada.
Abstract:
Interfacial flow instabilities in film manufacturing can significantly impact product quality, leading to defects such as waviness, film clarity issues, or layer delamination in multilayer films. These instabilities arise from complex interactions between material rheological properties such as shear and extensional viscosities, and processing conditions. One critical factor influencing stability is the design of the extrusion die, which governs how polymer melts are distributed and flow within the system. Proper die design optimizes flow residence time, the required layer ratio range and the corresponding flow rates thereby reducing instability risks.
The presentation will further discuss the types of interfacial instabilities, namely, wave instability, zig-zag instability and reactive instability. How die designs can influence these types of instabilities will be presented. Advanced rheological models and computational simulations can help predict and mitigate these effects; some examples will be shown.
Karen Xiao | Macro Engineering & Technology | Canada
11:30 – 12:00
High-Pressure Melt Flow Behaviour of Polymer Composites in Experiments, Processing, and Modelling
Dietmar Auhl | Berlin Institute of Technology (TU Berlin) | Germany
12:00 – 13:30
Lunch & Exhibition
RHEOLOGY OF POLYMERIC MATERIALS I
(Chairman: Savvas George Hatzikiriakos)
13:30 – 14:00
Shear-Induced Crystallization of Polypropylene Blends
Autors:
Masayuki Yamaguchi a), Khunanya Janchai b) and Shion Kitabatake c)
Affiliation:
Graduate School of Advanced Science and Technology, Japan Advanced Institute of Science and Technology Asahidai, Nomi, Ishikawa 923-1292 JAPAN.
Contacts:
a) Corresponding author:
b)
c)
Abstract:
Crystallization behaviors after shear history were studied using polypropylene (PP) blends with polymethylmethacrylate (PMMA) having low molecular weight. The PMMA addition enhanced shear-induced crystallization greatly, which was attributed to the excess deformation of continuous PP after the glassification of deformed PMMA droplets. Moreover, the addition of low-density polyethylene (LDPE) was also found to accelerate shear-induced crystallization of PP. During cooling at a constant rate, LDPE showed strain-hardening under shear flow due to the increase in the Weissenberg number. As a result, deformed LDPE droplets were hardly deformed further, leading to the excess deformation of PP. The marked shear-induced crystallization for both cases resulted in high orientation of PP chains.
Masayuki Yamaguchi | Japan Advanced Institute of Science and Technology | Japan
14:00 – 14:30
Orientation of polyethylene films for modulus enhancement
Autor:
Jaap den Doelder
Affiliation:
Eindhoven University of Technology, Netherlands.
Abstract:
Recyclability of flexible packaging is challenged when films consist of multiple materials. There is promise in redesigning such packages to be made of one main polymer type, while still allowing multiple grades within the type in multiple layers. Single-layer film properties depend on the macromolecular nature of the composition but also on how the polymers are processed. In particular, PE classically lacks stiffness, but sub-melt orientation can enhance modulus significantly. This contribution explores the interaction of polymer architecture characteristics with processing conditions for modulus enhancement. On the polymer side, effects of density, molar mass, molar mass distribution, and branching distribution are explored. On the processing side, attention is given to the effects of orientation temperature, draw ratio, and stretching rate. Base films consist of compression molded and blown films to explore the effect of baseline orientation. Finally, films have been re-extruded to study recyclability, in particular into the same application.
Jaap den Doelder | Eindhoven University of Technology | Netherlands
14:30 – 15:00
Coffee break & Exhibition
RHEOLOGY OF POLYMERIC MATERIALS II
(Chairman: Roland Kádár)
15:00 – 15:30
Elasticity of Polymer Melts Filled with Glass Microspheres
Autors:
Marta Czornik a), Martina Nevoralová b) and Zdeněk Starý c)
Affiliation:
Institute of Macromolecular Chemistry, Academy of Sciences of the Czech Republic, Heyrovsky Sq. 2, 162 06 Prague 6, Czech Republic.
Contacts:
a)
b)
c) Corresponding author:
Abstract:
This contribution concerns with rheology of polymer composites containing glass microspheres of different sizes. Special attention is paid to the elasticity of filled polymer melts characterized by a die swell of the extrudates. The composites are prepared in a way that the interfacial area between the polymer and the filler particles is kept constant. This allows us to study the effect of the polymer-particle interactions on the viscosity and elasticity of the composite melts systematically. The findings obtained imply that whereas the viscosity of the composites is governed mainly by the behavior of polymer matrix and filler concentration, the die swell as a parameter describing elasticity is affected by the interfacial area.
Zdeněk Starý | Institute of Macromolecular Chemistry CAS | Czech Republic
15:30 – 16:00
Analysis of the Fatigue Behavior of Solid Polymers and Elastomers via Fourier Transform of the Stress
Autors:
Anika Goecke 1), Valerian Hirschberg 2), Denis Rodrigue 3), and Manfred Wilhelm 1, a)
Affiliations:
1) Karlsruhe Institute of Technology, Institute for Chemical Technology and Polymer Chemistry, Engesserstrasse 18, 76131 Karlsruhe, Germany.
2) Technical University of Clausthal, Institute of Technical Chemistry, Arnold-Sommerfeld-Str. 4, 38678 Clausthal-Zellerfeld, Germany.
3) Department of Chemical Engineering and CERMA, Université Laval, 1065 Avenue de la Médecine, Quebec, QC, G1V 0A6, Canada.
Contact:
a) Corresponding author:
Abstract:
The fatigue behaviour of several polymers and elastomers (e.g. PS, PS-PI block copolymers, PE, ethyl-vinyl-acetate, PE) under oscillatory torsion and tension was investigated. Large amplitudes were applied and the nonlinear stress response and was analysed via Fourier Transform (FT) to quantify nonlinear contributions as higher harmonics.1–3 The tests were conducted in the solid state at room temperature using rectangular and rotational bone shaped specimen. To monitor changes in the sample such as cracks the samples were filmed by a video camera. The Analysis of the time evolution of the linear parameters (G’(t), G’’(t)) and the nonlinear parameters (higher harmonics, i.e. I2/1(t), I3/1(t)) as well as their cycle number depending derivatives and integrals allows a detection and description of specific events (e.g. crack growth and propagation), a prediction of the failure lifetime and the establishment of failure criteria. The linear parameters (G’, G’’) show a monotonic decrease over time, while the intensity of I3/1 (relative amplitude of the third harmonic to the fundamental one) steadily increased until failure.4 The behaviour of these three parameters were found to change linear with time (number of cycles) shortly after the beginning of the experiment, until failure occurs. For the undamaged specimen, the nonlinear parameter I2/1 (relative amplitude of the second harmonic to the fundamental one) is within the noise level, however its intensity increases with the appearance of macroscopic cracks.5 It is shown that the higher harmonics as a new parameter allow substantially earlier detection and prediction of failure.
References:
- V. Hirschberg, M. Wilhelm, D. Rodrigue, Polymer Testing 60, 343–350 (2017).
- V. Hirschberg, L. Faust, D. Rodrigue, M. Wilhelm, Macromolecules 53, 5572–5587 (2020).
- V. Hirschberg, L. Faust, M. Wilhelm, D. Rodrigue, Macromol. Mat. Eng. 306, 2100165 (2021).
- V. Hirschberg, M. Wilhelm, D. Rodrigue, J. Appl. Polym. Sci. 135, 46634 (2018).
- V. Hirschberg, L. Schwab, M. Cziep, M. Wilhelm, D. Rodrigue, Polymer 138, 1–7 (2018).
Manfred Wilhelm | Karlsruhe Institute of Technology (KIT) | Germany
18:30
Conference dinner
July 31, 2025
RHEOLOGY OF POLYMERIC MATERIALS III
(Chairman: Alan Jeffrey Giacomin)
8:00 – 8:30
A Few Rheological Aspects Regarding Magnetic Field Induced Nanostructure Alignment in Soft Materials
Autors:
Viney Ghai a) and Roland Kádár b)
Affiliation:
Chalmers University of Technology, Industrial and Materials Science, 412 96 Göteborg, Sweden.
Contacts:
a)
b) Corresponding author:
Abstract:
Controlling nanostructure orientation in soft materials is central for multifunctional materials. Here, we refer a novel orientation method using a magnetic field inside a Halbach-array capable of arbitrary long-range orientation in soft matter systems. We examine some early evidence of the critical role of rheology in facilitating orientation inside the Halbach array and preserving it for further curing.
Roland Kádár | Chalmers University of Technology | Sweden
8:30 – 9:00
Amazing Effects of the Mesoscopic Elasticity of Fluids: Application to Polymer Melts and Blood Plasma
Autors:
Laurence Noirez 1, a) and Ursula Windberger 2, b)
Affiliations:
1) Laboratoire Léon Brillouin (CEA-CNRS), Université Paris-Saclay, CE-Saclay, 91191 Gif-sur-Yvette Cédex, France.
2) Medical University of Vienna, Center for Anatomy and Cell Biology, Währingerstrasse 13, 1090 Vienna, Austria.
Contacts:
a) Corresponding author:
b)
Abstract:
Elasticity, the ability to respond spontaneously and reversibly to applied stress, is one of the oldest physical properties identified in condensed matter. Long considered as a solid character, it has recently been demonstrated that mesoscopic fluids are also endowed with (shear) elasticity. These new elements indicate that on a small scale, the molecules of the fluid are not dynamically independent but are elastically correlated. As consequence, the mesoscopic fluid is dependent on local potentials and the mechanics of continuous media no longer applies. This property is also revealed in Human Blood plasma when viscoelastic measurements are carried out on full wetting interfacial conditions. In this frame, and since elastic correlations allow mesoscopic liquids to propagate shear waves, we highlight that the emergence of non-equilibrium temperatures generated in the fluid by mechanical stress. New horizons in Rheology are opening up to explore and broaden our knowledge of the properties of fluids.
Laurence Noirez | Université Paris-Saclay | France
9:00 – 10:30
Coffee break & Poster section & Exhibition
A novel multifunction die for simultaneous measurement of steady-state viscosity, first normal stress difference and flow instability of viscoelastic liquids via capillary rheology
Autors:
Xiaohe Xu 1, a), Masood Khabazian Esfahani 2), Andrea Causa 3) and Manfred Wilhelm 1)
Affiliations:
1) Institute for Technical Chemistry and Polymer Chemistry (ITCP), Karlsruhe Institute of Technology (KIT), Engesserstraße18, 76131 Karlsruhe, Germany.
2) tesa SE, Hugo-Kirchberg-Straße 1, 22848 Norderstedt, Germany.
3) Pirelli & C. S.p.A., Viale Piero e Alberto Pirelli n. 25, 20126 Milan, Italy.
Contact:
a) Corresponding author:
Abstract:
As one of the core processes in polymer processing, extruders are often used to convert the polymer melts into pipes, sheets, films, etc. The design and optimization of the extrusion process require an increasing understanding of viscoelastic properties to ensure the processibility, appropriate dimensions, and smooth surface of extrudates, especially at high shear rates.
In this study, a new multifunction die capable of simultaneously determining steady state shear viscosity, steady state first normal stress difference coefficient , and characteristic frequencies of extrudate surface instability
has been developed. An industrial low-density polyethylene (LDPE) was applied to evaluate the performance of the multifunction die. The steady state shear viscosities obtained by multifunction die were compared to the magnitude of the complex viscosities obtained from oscillatory shear measurements. The validity of the empirical Cox-Merz rule was found. The steady state first normal stress difference coefficients
calculated by the exit pressure method [1] were compared to the
obtained from novel normal stress die [2] and transient shear measurements at rotational rheometer using cone-plate geometry. The validity of the exit pressure method is further supported by the agreement of measured first normal stress difference coefficients Ψ1 data with hierarchical multimode molecular stress function (HMMSF) model [3] prediction. The characteristic frequencies
of extrudate surface undulation were obtained by a built-in highly sensitive piezoelectric pressure transducer using autocorrelation function and power spectral density diagram. The characteristic time periodicities
obtained from the multifunction die, which are the inverse of the
, were compared with the
obtained by the offline optical analysis. The characteristic time periodicities of extrudate surface undulation were found to follow a power law model as a function of apparent shear rate with a scaling exponent of -0.96. This power law model can then be used to predict characteristic time periodicities of extrudate surface undulation at high shear rates.
References:
- C.D. Han, Trans. Soc. Rheol. 1974, 18, 163–190.
- M. Khabazian Esfahani, C.K. Georgantopoulos, I.F.C. Naue, J. Sunder, M. Wilhelm, J. Appl. Polym. Sci. 2022, 139.
- E. Narimissa, M.H. Wagner, Polymer 2016, 104, 204–214.
Xiaohe Xu | Karlsruhe Institute of Technology (KIT) | Germany
Modification of Mechanical Properties of Isotactic Polypropylene through Crystalline-Form Transformation
Autors:
Yuta Fukuda a) and Masayuki Yamaguchi b)
Affiliation:
Japan Advanced Institute of Science and Technology, 1-1 Asahidai, Nomi, Ishikawa, 923-1292, Japan.
Contacts:
a)
b) Corresponding author:
Abstract:
Two types of isotactic polypropylene (PP) films having different morphology with a similar crystallinity were prepared to investigate the effect of tangential daughter lamellae on the tensile behavior in the solid state. One film was prepared by cooling from the molten state to 40 ℃ and then exposed to annealing at 100 ℃, while the other was quenched at 0 ℃ followed by annealing at 100 ℃. The former film exhibited spherulite texture with α-form crystals, in which cross-hatch structure was developed. In the case of the latter one, mesophase with nodular structure was generated when quenched at 0 ℃. During the post-process annealing, the mesophase was turned into α-form crystals without cross-hatch structure. It was found from the tensile tests that yield and ultimate stresses of the latter film were higher than those of the former film with cross-hatch structure. Considering that their crystallinities were almost the same, the difference in the tensile properties should be ascribed to their morphology. Some of α crystals in the former film must be in the tangential daughter lamellae in the cross-hatch structure, which did not contribute to the increase in tie chains. This must be the origin of poor mechanical properties of the film with cross-hatch structure.
Yuta Fukuda | Japan Advanced Institute of Science and Technology | Japan
Anomalous Expansion of Poly(lactic acid) with Fibrils under Post-Process Annealing
Autors:
Hoang-Giang Dai Vo a) and Masayuki Yamaguchi b)
Affiliation:
Graduate School of Advanced Science and Technology, Japan Advanced Institute of Science and Technology 1-1 Asahidai, Nomi, Ishikawa, 923-1292, Japan.
Contacts:
a)
b) Corresponding author:
Abstract:
Shrinkage is one of the issues for the dimensional stability of plastic products during post-process annealing. This study proposes a new method to control the dimensional changes using molecular orientation. Poly(lactic acid) (PLA) blends with a low-molecular-weight poly(vinyl alcohol) (PVA) were injected into a mold using an injection-molding technique. The injection-molded bar showed an anomalous expansion to the flow direction during post-process annealing beyond 80 °C, although the PLA bar showed shrinkage. Furthermore, PLA containing N,N′-ethylenebis(12-hydroxystearamide) (EBHS), known as a fibrous nucleating agent, showed a similar phenomenon. EBHS segregated and formed a fibrous structure in PLA during quench process. It was found that EBHS oriented in the machine direction (MD) under an applied shear flow, which acted as a pseudo-shish. During post-process annealing, PLA crystals developed from the surface of oriented EBHS as kebabs, resulting in an increase in molecular orientation. This increase in molecular orientation prevented the shrinkage of PLA during post-process annealing.
Hoang-Giang Dai Vo | Japan Advanced Institute of Science and Technology | Japan
Numerical Bifurcation Analysis using Deflated Continuation Method — Cross-Slot Flow of FENE-CR Viscoelastic Fluid
Autors:
Vít Průša a) and Ladislav Trnka b)
Affiliation:
Faculty of Mathematics and Physics, Charles University, Sokolovská 83, Praha 8 – Karlín, CZ 186 75, Czech Republic.
Contacts:
a) Corresponding author:
b)
Abstract:
We study bifurcation behaviour of viscoelastic fluid flows, in particular we investigate steady flow of viscoelastic
FENE-CR fluid in a cross-slot geometry. We first revisit the FENE-CR viscoelastic fluid model, and we identify key thermodynamic
quantities that are of interest in the subsequent computations. Then we proceed with numerical bifurcation analysis, and we use
a deflation technique to find distinct solutions to the corresponding system of steady nonlinear partial differential equations. This
approach differs from previous studies on the same problem. While previous studies are based on tracking a randomly initialised
solution to the evolutionary governing equations until the solution reaches a non-trivial steady state, in the present study the
bifurcation diagrams are computed systematically by finding multiple solutions the steady governing equations. The present
approach allows us, among others, to systematically follow all steady state branches, both symmetric and non-symmetric ones.
The steady governing equations are discretised using the finite element method, and in order to preserve qualitative properties
of the governing equations we use a specific finite element formulation based on the logarithm reformulation of the governing
equations and the DEVSS-TG/SUPG stabilization. The proposed approach is implemented using Firedrake system and defcon
library, and we recover results obtained in previous studies on FENE-CR viscoelastic fluid flow in the cross-slot geometry. This
benchmarking confirms the viability of finite element/deflated continuation based approach in numerical study of bifurcations in
viscoelastic fluid flows.
Ladislav Trnka | Charles University in Prague | Czech Republic
Rheology as a Valuable Tool for Probing of Conductive Structures in Polyethylene Composites
Autors:
Martina Nevoralová 1, a), Zdeněk Starý 1, b), Jiří Hodan 1, c), Francesco Piana 1, d), Jiří Pfleger 1, e), Ewa Pavlova 1, f) and Lubomír Kubáč 2, g)
Affiliations:
1) Institute of Macromolecular Chemistry, Academy of Sciences of the Czech Republic, Heyrovsky Sq. 2, 162 06 Prague 6, Czech Republic.
2) Centrum Organické Chemie, s.r.o., Rybitví 296, 533 54 Rybitví, Czech Republic.
Contacts:
a) Corresponding author:
b)
c)
d)
e)
f)
g)
Abstract:
The rheology of conductive polymer composites has attracted much attention due to the high sensitivity of this method to investigate the formation of conductive particle structures. In this contribution, we evaluated the effect of two specific procedures for the preparation of the single-wall carbon nanotube-filled nanocomposites in terms of their concentration and the quality of the dispersion in the high-density polyethylene matrix. In particular, we focused on the influence of the promising non-covalent modification process using alkylated pyrene resulting in good dispersion in non-polar environments. It was proved that the properties of the nanocomposites were controlled by the modification procedure used. The results obtained proved better dispersion and higher mobility of conductive nanoparticles in the case of the simpler modification procedure used. In addition, the rheological and electrical measurements before and after isothermal annealing in the molten state showed further conductivity increase. This approach allowed us to investigate the formation of conductive structures in a comprehensive manner. The high sensitivity of the measurements in the oscillatory shear flow to the changes in composite microstructure confirms their benefits for probing the conductive structure formation.
Martina Nevoralová | Institute of Macromolecular Chemistry CAS | Czech Republic
Reversible Polymer Networks: Smart Materials Investigated by Rheological Methods
Autors:
Beata Strachota 1, a), Adam Strachota 1, b), Petr Kadlec 2, c) and Todor Batakliev 3, d)
Affiliations:
1) Institute of Macromolecular Chemistry, Academy of Sciences of the Czech Republic, Heyrovského nám. 2, 162 00 Praha 6, Czech Republic.
2) Department of Materials and Technology, Faculty of Electrical Engineering, University of West Bohemia, Univerzitní 2795/26, 301 00 Plzeň, Czech Republic.
3) Institute of Mechanics, Bulgarian Academy of Sciences, Acad. G. Bonchev Str., Block 4, 1113 Sofia, Bulgaria.
Contacts:
a)
b) Corresponding author:
c)
d)
Abstract:
The development of self-healing polymers for electrical insulation is of considerable practical interest, driven by the demand for durability and eventual repairability of such materials in high-voltage applications [1, 2].
The present study [3, 4] is dedicated to novel epoxy resins with self-healing ability, based on interpenetrating polymer network structure (IPN), which combines a permanent epoxy-amine (EP) network with a reversible one (DA), crosslinked by Diels-Alder chemistry. The interpenetrating DA sub-network was found to provide very efficient albeit not complete thermally induced self-healing, even after specimen disruption (the latter leads to irreversible damage to the permanent EP network). The permanent EP sub-network, on the other hand, provides good shape stability to the material during the self-healing process.
The employed EP network was based on bisphenol A diglycidyl ether (DGEBA) cured by poly(propylene oxide)-α,ω-diamine (D) of different PPO chain length (230, 400, and 2000 g/mol). The intercalated reversible DA sub-network was obtained from 4,4′-Bismaleimido-diphenylmethane (BMI) and tetrakis-furan-functionalized poly(propylene oxide) (FD). The latter co-monomer was accessible via chemical modification of the above-mentioned “D”.
Rheological and thermo-mechanical analyses were helpful in establishing the optimal mass ratio of the EP and DA sub-networks, the best curing modes (IPN system synthesis), the most suitable material healing procedures, as well as in characterizing the dynamics of the reversible DA bonds, which is of key importance during the self-healing.
The increasing length of the poly(propylene oxide) (PPO) chain in the D and FD components down-shifted especially the glass transition temperature and the rubbery modulus, but it also moderately influenced the temperature of the dissociation of the DA bonds in the reversible sub-network. The dielectric and hence the insulating properties were the most attractive with the shortest PPO chains. Undesired crosslinking side reactions between EP and DA components were possible to suppress efficiently by careful tuning of the curing and self-healing procedures – this was most easily achieved with longer PPO chains.
The IPN network based on D and FD macromonomers with 400 g/mol PPO chains proved to be the most promising self-healing epoxy insulator system.
Acknowledgments:
This research was supported by the Czech Academy of Sciences, project Nr. BAS-25-03 and by the Bulgarian Academy of Sciences, project Nr. IC-CZ/01/2025-2026.
References:
- Y. Yang, Z. M. Dang, Q. Li and J. He, “Self-Healing of Electrical Damage in Polymers”, Adv. Sci. 7(21), 2002131 (2020).
- W. Bian, W. Wang and Y. Yang, “A Self-Healing and Electrical-Tree-Inhibiting Epoxy Composite with Hydrogen-Bonds and SiO2 Particles”, Polymers 9(9), 431 (2017).
- B. Strachota, J. Hodan, J. Dybal and L. Matějka, “Self‐Healing epoxy and reversible Diels‐Alder based interpenetrating networks”, Macromol. Mater. Eng. 306(1), 2000474, (2020).
- B. Strachota, A. Strachota, P. Kadlec, and T. Batakliev, “Self-healing Epoxy Insulator Polymers Based on Interpenetrating Networks with Diels-Alder Chemistry”, Polym. Test., submitted (2025).
Adam Strachota | Institute of Macromolecular Chemistry CAS | Czech Republic
Rheology as an Effective Tool for the Comprehensive Characterization of Hydrogel Systems
Autors:
Ludmila Kouřilová a), Jiří Smilek b), Martin Kadlec c), Miloslav Pekař d) and Petr Sedláček e)
Affiliation:
Brno University of Technology, Faculty of Chemistry, Institute of physical and applied chemistry, Physical chemistry of surfaces and colloids, in Czech, Purkyňova 464/118, CZ-612 00 Brno, Czech Republic.
Contacts:
a) Corresponding author:
b)
c)
d)
e)
Abstract:
Hydrogels, as polymeric materials with a high-water retention capacity, find extensive applications in biomedicine, pharmacy, and the food industry. Each application imposes different requirements on the material, making rheological characterization crucial for optimizing their functional properties. This study focuses on unconventional rheometric experiments aimed at determining the mechanical properties of hydrogel materials. The optimization of viscoelastic property assessment of hydrogels in relation to relative humidity was carried out using a humidity chamber, allowing for the simulation of real-world conditions to which the material will be exposed, such as temperature, relative humidity, and mechanical load. This enables the evaluation of whether the hydrogel is suitable for the intended application. Furthermore, it was demonstrated that rheometry can effectively track the evolution of viscoelastic properties during gel swelling. Lastly, the study optimized the determination of hydrogel mechanical properties using the squeeze test, providing valuable insights into sample homogeneity and the material’s response to compression. Additionally, this work highlights the critical importance of selecting appropriate measurement parameters, as they significantly influence the accuracy and reliability of the results.
Miloslav Pekař | Brno University of Technology | Czech Republic
Interface Rotational Rheometry – Treatment of Data Measured Using BiCone Geometry
Autors:
Věra Pěnkavová a), Eliška Lyko Vachková b) and Jaroslav Tihon c)
Affiliation:
Institute of Chemical Process Fundamentals of the Czech Academy of Sciences, Rozvojová 135, 16500 Prague, Czech Republic.
Contacts:
a) Corresponding author:
b)
c)
Abstract:
Interfacial rheometry is of great interest nowadays. The quality of both liquid/air and liquid/liquid interfaces influences foaming, emulsification, fluid separation, etc. of a given system either in certain technologies, environment or in living organism. The quality of an interface can be described by (i) surface/interface tension, (ii) surface/interface Gibbs elasticity, which gives information about the resistance of the interface to change in size, and (iii) surface/interface viscoelastic properties, which describe the resistance of the interface to shear deformation. The viscoelastic properties can be measured e.g. by optical rheometry, needle rheometry or by rotational rheometers with sensors of either ring geometry or BiCone geometry. In the case of using rotational rheometers with BiCone geometry, the data treatment is not trivial because the total drag force is given by the sum of the interface and bulk contributions. This paper presents and discusses different ways of handling data measured with BiCone geometry.
Věra Pěnkavová | Institute of Chemical Process Fundamentals CAS | Czech Republic
Squeezing Flow of Low-Concentration Collagen: Application of a Modified Mathematical Model and the Effect of Electron Beam Irradiation
Autors:
Fadi Alzarzouri 1, a), Jaromír Štancl 1, b), Jan Štípek 1, c), Milan Houška 2, d) and Jan Skočilas 1, e)
Affiliations:
1) Faculty of Mechanical Engineering, Czech Technical University in Prague, Technická 4, 166 29 Prague 6, Czech Republic.
2) Food Research Institute Prague, Radiová 7, 102 31 Prague 10, Czech Republic.
Contacts:
a) Corresponding author:
b)
c)
d)
e)
Abstract:
This study examines the effect of electron beam irradiation on behaviour of low-concentration collagen at varying boundary conditions under the squeezing flow. Two models are considered: perfect lubrication (ideal slip) and no-slip conditions. The experimental data were used to evaluate the parameters of a modified mathematical model. The results showed a significant impact of high irradiation doses on collagen material and the perfect lubrication model provided a better overall fit to the experimental data. This contribution enhances the understanding of the viscoelastic properties of low-concentration collagen under squeezing flow, providing insights into its flow behaviour which is essential for applications.
Fadi Alzarzouri | Czech Technical University in Prague | Czech Republic
INTRODUCTION OF NOVEL RHEOLOGICAL TOOLS
(Chairman: Zdeněk Starý)
10:30 – 11:00
Mastering the Rosand Capillary Rheometer: Features, Functions, and Full Potential
Autor:
Levente Szántó
Affiliation:
NETZSCH Gerätebau GmbH, Wittelsbacherstrasse 42, 95100, Selb, Germany.
Abstract:
In polymer processing and beyond, there is a constant drive to optimize processes in pursuit of economic, ecological, and energy efficiency. Consequently, researchers continually push their own limits and the capabilities of thermal analysis equipment, such as high-pressure capillary rheometers. Through extensive instrument and software development, countless hours of work have been invested to support scientists and the industrial community in their experiments, investigations, and daily quality assurance.
By employing the ROSAND high-pressure capillary rheometer and the novel FreeFlow dies, the accurate determination of the uniaxial and planar extensional behavior of polymer melts has become possible. However, despite these advancements, the standard measurement types implemented in the accompanying software can still hinder a full examination and understanding of material behavior under specialized conditions. To fully harness the potential of the ROSAND rheometer, the Flowmaster software—via its Low Level Script feature—opens up virtually limitless possibilities, allowing users to create unique measurement without constraints and reveal the desired material characteristics.
Ultimately, the flexibility offered by the ROSAND high-pressure capillary rheometer not only drives economic growth but also fosters ecological and energy efficiency in polymer processing.
Levente Szántó | NETZSCH-Gerätebau GmbH | Germany
11:00 – 11:30
Optimizing Electrode Manufacturing Through Combined Rheological and Impedance Measurements
Autors:
Lukas Schwab 1, a), Kevin Whitcomb 2), and Yuki Kawata 3)
Affiliations:
1) Waters GmbH, TA Instruments, Helfmann-Park 10, 65760 Eschborn, Germany.
2) TA Instruments-Waters LLC, 159 Luken Drive, New Castle, DE 19720, USA.
3) TA Instruments-Waters LLC., 5-2-4, Nishigotanda, Shinagawa-ku, Tokyo 141-0031, Japan.
Contact:
a) Corresponding author:
Abstract:
Electrode slurries are composed of active materials, conductive additives, binders, and more. Such slurries must remain stable during storage, disperse easily, and be flowable for uniform coating. During these processes they experience various shear stresses and shear rates, making full characterization challenging due to the dynamic interactions between components. Rheology helps assess suspension stability and viscosity at different shear stresses but cannot determine the structure of the carbon black conductive network, as larger active material particles may dominate bulk properties.
Poor distribution or aggregation of carbon black can lead to higher electrical resistance in electrodes, causing increased heat generation and shorter cycle life. Electrochemical impedance spectroscopy (EIS) is a technique that uses alternating current or potential across a range of frequencies to probe the sample. It can distinguish between events occurring over different time scales, such as conductivity within a solid electrode versus ionic conductivity of the electrolyte. Combining rheology and EIS allows for the characterization of both rheological behavior and the structure of the carbon black conductive network under relevant manufacturing conditions.
We introduce a new accessory for the Discovery HR rheometer series, which combines rheology and impedance spectroscopy to measure slurry viscoelasticity and electrochemical impedance in a flow field. We report the results of simultaneous measurements of viscoelasticity and impedance of cathode slurry under flow conditions for Li-ion battery cathode slurries and carbon paste. For cathode slurries, impedance data was recorded during a three-interval shear test. Slurries with 2% carbon nanotubes showed almost complete recovery of the filler network, indicating good filler dispersion. In contrast, slurries with higher CNT content showed much lower impedance in the recovery step, indicating poorer filler dispersion.
Lukas Schwab | Waters GmbH, TA Instruments | Germany
11:30 – 12:00
Novel Extensional Rheometry Techniques for a Rotational Rheometer Platform
Autors:
Philana Kruse a) and Jan Haeberle b)
Affiliation:
Anton Paar Germany GmbH, 73760 Ostfildern, Germany.
Contacts:
a) Corresponding author:
b)
Abstract:
Performing extensional measurements on a rotational rheometer has long been established for solid samples using rectangular fixtures and for films using SER-like geometries [1]. In this work, we show how the modularity of a rotational rheometer platform can be utilized to extend the measuring range of existing methods and enable the application of techniques that previously required a separate device.
In particular, we show how incorporating a second motor into measurements with SER can greatly improve the available torque range, thereby extending the measuring range to lower shear rates/ lower viscosity samples. The same setup can also be used to further enhance the method recently suggested by Parisi et. al [2] where the sample is mounted at an angle in order to achieve increased maximum deformations. We improve upon this method by additionally controlling the vertical movement of one of the SER drums to actively control the inclination angle during measurement. Having optical access to the measurement setup during the entire experiment allows validation of the inclination angle.
Finally, we show that by equipping the rheometer with a lower linear drive and combining the setup with a high-speed camera, we can perform capillary breakup experiments on low viscosity liquids. The rapid motion enabled by the linear drive and an optimized optical setup are required to perform these measurements at a level that previously required a separate device.
References:
- L. Faust, M.-C. Röpert, M. K. Esfahani, M. Abbasi, V. Hirschberg, and M. Wilhelm, “Comb and Branch‐on‐Branch Model Polystyrenes with Exceptionally High Strain Hardening Factor SHF > 1000 and Their Impact on Physical Foaming,” Macromol Chem Phys, 2022.
- D. Parisi, S. Coppola, S. Righi, G. Gagliardi, F. S. Grasso, and F. Bacchelli, “Alternative use of the Sentmanat Extensional Rheometer to investigate the Rheological Behavior of industrial Rubbers at very large Deformations,” Rubber Chem. Technol., vol. 95, no. 2, pp. 241–276, May 2022, doi: 10.5254/rct.21.77948
Philana Kruse | Anton Paar Germany GmbH | Germany
12:00 – 13:30
Lunch & Exhibition
NON-NEWTONIAN FLUID MECHANICS
(Chairman: Jiří Vlček)
13:30 – 14:00
Enhancing Coupled Numerical Simulations of Viscoelastic Flows Through Physical Property Analysis
Autors:
Gabriel M. Magalhaes 1, a), Ricardo Costa 2, b) and João Miguel Nóbrega 2, c)
Affiliations:
1) PIEP – Centre for Innovation in Polymer Engineering, University of Minho, Azurém Campus, 4800-058 Guimarães, Portugal.
2) Institute for Polymers and Composites, University of Minho, Azurém Campus, 4804-058 Guimarães, Portugal.
Contacts:
a) Corresponding author:
b)
c)
Abstract:
Polymeric fluids exhibit complex viscoelastic behavior governed by nonlinear constitutive equations. Considering the full mathematical formulation is essential for accurately representing the behavior of these fluids. Numerical simulations with viscoelastic fluids can face stability and convergence challenges, especially when modeling real-world polymer processing test cases. To address these issues, a coupled solver for multi-mode viscoelastic flows was developed within the foam-extend framework, where pressure, velocity, and a selected viscoelastic mode are solved together in a single block system, while the remaining modes follow a segregated procedure. A key question is how to select the mode to include in the block system, as this choice can significantly affect both computational efficiency and solution accuracy. This study systematically investigates the impact of coupling each individual mode in a six-mode fluid. The results highlight how mode selection influences convergence time and overall solution quality. Additionally, a novel convergence assessment that was recently proposed is further tested. It is based on physical flow characteristics rather than solely on numerical residuals. Specifically, the variables such as total pressure drop and outlet flow distribution in three distinct zones evolution are tracked. This approach avoids inconsistencies caused by different residual normalizations in segregated and fully coupled solvers and provides a more reliable measure of convergence across various simulation strategies.
João Miguel Nóbrega | University of Minho | Portugal
14:00 – 14:30
Measurement and Modeling of Extensional Rheology to Understand Flow Instabilities in Polymer Processing
Autors:
Martin Zatloukal a), Jiří Drábek b), Tomáš Barbořík c), Jan Musil d) and Jiří Juračka e)
Affiliation:
Department of Polymer Engineering, Faculty of Technology, Tomas Bata University in Zlín, Vavrečkova 5669, 760 01 Zlín, Czech Republic.
Contacts:
a) Corresponding author:
b)
c)
d)
e)
Abstract:
In this work, the uniaxial extensional viscosity, hE,U, and the planar extensional viscosity, hE,P, were determined for various polyolefins via flow through abrupt contraction using FreeFlow dies [1-4] and different methodologies [5-11]. The obtained data for hE,U were compared with the corresponding data from Münstedt’s oil bath filament stretching rheometer [12-16]. Furthermore, the applicability of stereolithography (SLA) additive manufacturing technology was tested for the production of capillary rheometer dies from an ultraviolet-treated polymer composite resistant to high temperatures. Then, multi-mode viscoelastic modified Leonov model [17-18] and recently proposed inelastic fluid model with an objective stretch rate parameter [19] were tested to understand their ability to describe rheological data for the polyolefin samples tested. Finally, extensional viscosity data together with viscoelastic flow modeling were used to understand flow stability in meltblown [20] and film casting [21-22] processes.
Acknowledgments:
The authors wish to acknowledge the Grant Agency of the Czech Republic (Grant No. 24-11442S) for the financial support and NETZSCH Gerätebau GmbH for providing the Rosand RH10-2 capillary rheometer. The authors would also like to thank Levente Szántó from NETZSCH Gerätebau GmbH for his support.
References:
- M. Zatloukal, J. Musil, Patent CZ 304382 (2014).
- M. Zatloukal, Patent CZ 305409 (2015).
- M. Zatloukal, Patent CZ 307664 (2018).
- M. Zatloukal, Patent CZ 309071 (2021).
- J. Drabek, M. Zatloukal, Flow-induced reduction of the monomeric friction coefficient using a branched environment in linear isotactic polypropylene melt. Macromolecules Article ASAP (2025). DOI: 10.1021/acs.macromol.5c00660
- M. Zatloukal, Measurements and modeling of temperature-strain rate dependent uniaxial and planar extensional viscosities for branched LDPE polymer melt. Polymer 104, 258-267 (2016).
- M. Zatloukal, J. Musil, Analysis of entrance pressure drop techniques for extensional viscosity determination. Polymer Testing 28(8), 843-853 (2009).
- F.N. Cogswell, Converging flow of polymer melts in extrusion dies. Polymer Engineering & Science, 12(1), 64-73 (1972).
- A.G. Gibson, Die entry flow of reinforced polymers. Composites, 20(1), 57-64 (1989).
- P. C. Beaupre, A Comparison of the Axisymmetric & Planar Elongational Viscosities of a Polymer. M.S. Thesis. Michigan Technological University, Houghton, 2002.
- Padmanabhan, M.: Evaluation of the entrance pressure drop method to estimate extensional viscosity. M.S. Thesis. University of Minnesota, Minesota, 1993.
- H. Münstedt, Various features of melt strain hardening of polymeric materials in uniaxial extension and their relation to molecular structure: review of experimental results and their interpretation. Rheologica Acta, 62 (7-8), 333–363 (2023).
- D. Auhl, F.J. Stadler, H. Münsted, Rheological properties of electron beam-irradiated polypropylenes with different molar masses. Rheologica Acta 51(11-12), 979–989 (2012).
- D. Auhl, F.J. Stadler, H. Münsted, Comparison of molecular structure and rheological properties of electron-beam- and gamma-irradiated polypropylene. Macromolecules 45(4), 2057–2065 (2012).
- D. Auhl, Molekulare struktur und rheologische eigenschaften stranhlenmodifizierter polypropylene. Ph.D, Dissertation, Der Technischen Fakultät der Universität Erlangen-Nürnberg, Erlangen, Germany, 2006. https://open.fau.de/server/api/core/bitstreams/1a63d236-e72b-447c-bef2-d5c65f2a4e38/content
- H. Münsted, D. Auhl, Rheological measuring techniques and their relevance for the molecular characterization of polymers. J. Fluid Mech.128 (1 Spec. Iss.), 62–69 (2005).
- A.I. Leonov, Nonequilibrium thermodynamics and rheology of viscoelastic polymer media. Rheologica Acta 15(2), 85–98 (1976).
- M. Zatloukal, Differential viscoelastic constitutive equations for polymer melts in steady shear and elongational flows. Journal of Non-Newtonian Fluid Mechanics, 113(2-3), 209-227 (2003).
- D. Yao, M. Zatloukal, Inelastic fluid models with an objective stretch rate parameter. Journal of Non-Newtonian Fluid Mechanics, 334, 105320 (2024).
- J. Drabek, M. Zatloukal, Meltblown technology for production of polymeric microfibers/nanofibers: A review. Physics of Fluids, 31(9), 091301 (2019).
- T. Barborik, M. Zatloukal, Importance of heat transfer in membrane extrusion process involving flow-induced crystallization. International Journal of Heat and Mass Transfer, 214, 124444 (2023).
- T. Barborik, M. Zatloukal, International Journal of Heat and Mass Transfer, manuscript in preparation (2025).
Martin Zatloukal | Tomas Bata University in Zlín | Czech Republic
14:30 – 15:00
End of the conference