Review
Polymer Science
Mohammed Abdul Samad
Summary: Polymer coatings have gained attention due to their low cost, ease of coating, low friction, and good anti-corrosion properties. Among various polymers, UHMWPE stands out for its excellent tribological properties, despite limitations such as low load-bearing capacity and low thermal stability. Researchers have developed various routes, including composite coatings, film systems, and dual film systems, to improve the tribological performance of UHMWPE coatings.
Article
Polymer Science
Noelle Billon, Romain Castellani, Jean-Luc Bouvard, Guilhem Rival
Summary: This paper explores the viscoelastic behavior during crystallization and melting of semicrystalline polymers, aiming to propose a preliminary model for the impact of crystallization and melting on the storage and loss moduli. The experimental results suggest that relying solely on the crystalline fraction is insufficient to model the rheology, while considering the microstructure at the spherulitic level could be more helpful. Additionally, the experiments enhance our understanding of the correlations between crystallization kinetics and its mechanical effects.
Article
Mechanics
Yuki Matsuoka, Yasuya Nakayama, Toshihisa Kajiwara
Summary: The study focuses on the quantitative prediction of shear thickening in suspensions in viscoelastic fluids, using numerical simulations that align with recent experimental results. The accurate estimation of the first normal stress difference of the matrix is crucial for predicting the shear thickening behavior in a Boger fluid matrix.
JOURNAL OF FLUID MECHANICS
(2021)
Article
Mechanics
L. A. Kroo, Jeremy P. Binagia, Noah Eckman, Manu Prakash, Eric S. G. Shaqfeh
Summary: In this study, a self-propelled axisymmetric swimmer that can only swim in a non-Newtonian fluid due to fluid elasticity is presented. The propulsion mechanism is demonstrated using a robotic swimmer, and optimized tail geometries are shown to enhance the propulsive signal. Additionally, the observations of the robot can be used to infer rheological properties of the surrounding fluid.
JOURNAL OF FLUID MECHANICS
(2022)
Article
Engineering, Mechanical
Sergey O. Ilyin, Svetlana N. Gorbacheva, Anastasiya Y. Yadykova
Summary: Dispersion of microfibrillated cellulose (MFC) in triethyl citrate is a typical grease with shear-thinning, shear-thickening, and viscoelastic properties. It can maintain its flowability at low temperatures (-50°C), making it potentially applicable as a low-temperature lubricant. Microfibrils reduce friction and wear on steel surfaces by filling irregularities and forming a chromium-enriched friction film.
TRIBOLOGY INTERNATIONAL
(2023)
Article
Mechanics
Kengo Fukushima, Haruki Kishi, Hiroshi Suzuki, Ruri Hidema
Summary: An experimental study was conducted to investigate the effects of the extensional rheological properties of drag-reducing wormlike micellar solutions on vortex deformation and turbulence statistics in 2-D turbulent flow. The results showed that vortex shedding and turbulence statistics were enhanced by the formation of wormlike micelles and by applying extensional stresses to the solution. The flow-induced structure made of wormlike micelles influenced the velocity fields and turbulence statistics in the flow, leading to characteristic changes in turbulent energy.
JOURNAL OF FLUID MECHANICS
(2022)
Article
Chemistry, Physical
Taiki Yoshida, Yuji Tasaka, Peter Fischer, Yuichi Murai
Summary: This study used ultrasonic spinning rheometry to investigate the time-dependent viscoelastic characteristics of montmorillonite dispersion, revealing different timescales based on shear conditions. Experimental methods categorized the rheological properties of the dispersion into parameters with three timescales, providing important insights into its complex rheological characteristics.
APPLIED CLAY SCIENCE
(2022)
Article
Materials Science, Paper & Wood
Svetlana N. Gorbacheva, Anastasiya Y. Yadykova, Sergey O. Ilyin
Summary: A novel method has been suggested to produce micro- and nanoparticles of cellulose through phase separation in a mixture of N-methylmorpholine N-oxide and dimethyl sulfoxide, using cooling or a precipitant. The size and crystallinity of cellulose particles, as well as their thickening abilities, were found to be influenced by the nature of the precipitant (water, methanol, or butanol). Despite different origins and sizes, cellulose particles had minimal impact on the rheology of dispersions, displaying typical gel properties.
Article
Engineering, Electrical & Electronic
Miroslav Piska, Katerina Urbancova
Summary: Modern orthopaedic implants typically consist of hard metal alloys or ceramics and a tribological sub-component made of soft materials. The machining technology is crucial for generating accurate shapes of implants that conform to joint function, with technology, cutting tools, and cutting conditions influencing the physical and mechanical properties of the entire implant and its longevity.
Article
Materials Science, Multidisciplinary
Wenhui Cao, Qi Ding, Peng Ding, Litian Hu, Chaobin Liu, Wei Yu
Summary: The rheological properties of PNIPAM microgels and the formation mechanism of tribofilms at the sliding interface during friction were investigated. It was found that PNIPAM microgels could effectively improve the tribological performance above the critical solution temperature, by forming a gel layer that changes the friction interface and reduces the friction coefficient.
ACS APPLIED POLYMER MATERIALS
(2022)
Article
Chemistry, Physical
Kailash Arole, Mohsen Tajedini, Anubhav Sarmah, Swarnima Athavale, Micah J. Green, Hong Liang
Summary: Ti3C2Tz nanoparticles can enhance the thermal conductivity, rheological properties, and lubrication performance of silicone and PAO oils. The addition of Ti3C2Tz increased the thermal conductivity by 16% in silicone oil and 23% in PAO oil. It also reduced the viscosity by 12.3% and 18.1% and decreased the friction by 23% and 65% in silicone and PAO oils, respectively.
JOURNAL OF MOLECULAR LIQUIDS
(2023)
Article
Chemistry, Applied
Maria Dimopoulou, Katerina Alba, Ian M. Sims, Vassilis Kontogiorgos
Summary: The study found that baobab fruit xylogalacturonans have unique rheological characteristics, with pH strongly impacting the viscoelasticity of the polysaccharides. Dispersion of fruit polysaccharides exhibited liquid-like behavior at low pH, while a weak gel network was observed at neutral pH.
CARBOHYDRATE POLYMERS
(2021)
Article
Materials Science, Multidisciplinary
Hikaru Hasegawa, Yuki Nohara, Erika Saiki, Toshiyuki Shikata
Summary: The dynamic viscoelastic behaviors of aqueous pullulan solutions were studied at different concentrations and temperatures. The relationships between relaxation time, compliance, viscosity, and concentration were analyzed, revealing the critical concentration for entanglement formation among pullulan molecules. The observed viscoelastic behaviors were explained using a theoretical model for associating polymers dissolved in good solvents.
ACS APPLIED POLYMER MATERIALS
(2021)
Article
Geochemistry & Geophysics
N. Casas, G. Mollon, A. Daouadji
Summary: Fault zones are composed of granular gouge, which contributes to friction stability. Different infill materials can be observed in mature fault zones, changing the rheological and frictional behaviors of the gouge. The study aims to understand the influence of grain-scale characteristics on slip mechanisms and gouge rheology by using the discrete element method. The findings suggest that gouge materials with high interparticle friction or high shear modulus may lead to faster earthquake ruptures.
JOURNAL OF GEOPHYSICAL RESEARCH-SOLID EARTH
(2023)
Article
Multidisciplinary Sciences
Tine Curk, Erik Luijten
Summary: The process of phase separation in elastic solids and viscous fluids is fundamental to the stability and function of soft materials. This study investigates the dynamics of phase separation and domain growth in viscoelastic materials, such as polymer gels, using analytical theory and Monte Carlo simulations. The results show that the domain size increases algebraically with a ripening exponent that depends on the viscoelastic properties of the material, and this behavior is different from the well-known Ostwald ripening process.
PROCEEDINGS OF THE NATIONAL ACADEMY OF SCIENCES OF THE UNITED STATES OF AMERICA
(2023)
Article
Polymer Science
Christos K. Georgantopoulos, Masood K. Esfahani, Ingo F. C. Naue, Manfred Wilhelm, Roland Kadar
Summary: The extrusion flow instabilities of two commercial polyethylenes (PE), both with similar weight average molecular weight, were characterized using capillary rheology, optical analysis, and modeling. The characteristic time periodicity τ* and spatial characteristic wavelength λ were obtained and compared using three different methods. It was found that both the characteristic time periodicity τ* and the spatial characteristic wavelength λ exhibit Arrhenius temperature-dependent behavior.
JOURNAL OF APPLIED POLYMER SCIENCE
(2023)
Article
Chemistry, Applied
Sylwia Wojno, Astrid Ahlinder, Annika Altskar, Mats Stading, Tiffany Abitbol, Roland Kadar
Summary: The influence of surface charge on the percolation, gel-point, and phase behavior of CNC suspensions was examined in relation to their nonlinear rheological material response. Desulfation decreased the CNC surface charge density which resulted in an increase in attractive forces between CNCs. The study found that nonlinear behavior marked the presence of a weakly percolated network at lower concentrations, regardless of whether the gel-point occurred at the biphasic -liquid crystalline transition or at the isotropic -quasi-biphasic transition.
CARBOHYDRATE POLYMERS
(2023)
Article
Chemistry, Multidisciplinary
Silvia D'Auria, Amir Masoud Pourrahimi, Alessia Favero, Peter Neuteboom, Xiangdong Xu, Shuichi Haraguchi, Marko Bek, Roland Kadar, Enrico Dalcanale, Roberta Pinalli, Christian Mueller, Jerome Vachon
Summary: Polyethylene based ionomers have been synthesized with thermo-mechanical and dielectric properties comparable to cross-linked polyethylene (XLPE), making them a promising alternative for high voltage insulation in future HVDC power cables. The ionomers feature similar crystallinity, melting temperature, rubber plateau modulus, and thermal conductivity as XLPE, while remaining melt-processable. Their production process is free of byproducts, resulting in a highly insulating material with low dielectric loss and DC electrical conductivity.
ADVANCED FUNCTIONAL MATERIALS
(2023)
Article
Chemistry, Multidisciplinary
Sylwia Wojno, Amit Kumar Sonker, Jelka Feldhusen, Gunnar Westman, Roland Kadar
Summary: Nonlinear material parameters are more sensitive than linear viscoelastic parameters to the onset of weakly interconnected networks in cellulose nanocrystal(CNC) isotropic suspensions. All surface-modified CNC suspensions resulted in isotropic gels. The length of the grafted chains and the degree of branching were the primary factors influencing the nonlinear material response.
Article
Materials Science, Multidisciplinary
Sajjad Pashazadeh, Alexandra Aulova, Christos K. Georgantopoulos, Marko Bek, Iakovos Vittorias, Ingo F. C. Naue, Manfred Wilhelm, Roland Kadar
Summary: This study investigates the influence of molecular weight and long-chain branching on the types of melt flow extrusion instabilities (MFEI). Four linear low-density polyethylenes (LDPEs) are extruded using a single-screw extruder coupled with an inline optical imaging system. Through the analysis of space-time diagrams constructed with an inline imaging system, three main MFEI types are identified, distinct from those observed in linear and short-chain branched polymers. Higher long-chain branching appears to have a stabilizing effect on the transition sequences.
MACROMOLECULAR MATERIALS AND ENGINEERING
(2023)
Article
Chemistry, Multidisciplinary
Shadi Rahimi, Teo Lovmar, Alexandra Aulova, Santosh Pandit, Martin Lovmar, Sven Forsberg, Magnus Svensson, Roland Kadar, Ivan Mijakovic
Summary: To combat bacterial infections in the post-antibiotic era, efforts are being made to engineer new materials with antibacterial properties. A new automated pipeline based on scanning electron microscopy images has been developed to predict the antibacterial potential of these materials. The density of sharp exposed edges of graphite-oriented nanoplatelets (GNPs) is a key factor in killing bacteria on contact.
Review
Engineering, Biomedical
Hengzhi Ruan, Alexandra Aulova, Viney Ghai, Santosh Pandit, Martin Lovmar, Ivan Mijakovic, Roland Kadar
Summary: To address the global threat of antimicrobial resistance, which is a common cause of healthcare-associated infections and imposes significant costs on healthcare systems, extensive research has been dedicated to developing polysaccharide-based strategies that prevent bacterial attachment and biofilm formation on surfaces. Polysaccharides, as essential building blocks for life and abundant renewable resources, have attracted attention for their intrinsic antibacterial activities. If efficiently transformed into antibacterial coatings for a wide range of surfaces and applications, polysaccharide-based coatings could have a substantial global impact. However, their ultimate success will depend on their potential for scalable, versatile, and affordable manufacturing processes.
ACTA BIOMATERIALIA
(2023)
Article
Materials Science, Composites
Sajjad Pashazadeh, Reza Ghanbari, Marko Bek, Alexandra Aulova, Tobias Moberg, Anders Brolin, Roland Kadar
Summary: For the first time, surface defects in highly-filled wood polymer composites (WPCs) are mapped using inline optical spectral analysis during single-screw extrusion. The effects of wood fiber content and drying on surface defects dynamics are resolved through space-time inline optical imaging. The study reveals that surface tearing appears at low shear rates and gradually decreases in spectral intensity with increasing shear rates/slip velocities. Increasing shear rates, wood fiber content, and drying have mitigating effects on surface tearing, but it still persists in undried samples even at high shear rates and high wall slip velocities. A regime dominated by bubbles on the extrudate surface is identified at high shear rates and low wood fiber contents in undried WPCs.
COMPOSITES SCIENCE AND TECHNOLOGY
(2023)
Article
Materials Science, Multidisciplinary
Benjamin Podmiljs, Spomenka Kobe, Tomaz Tomas, Marko Bek, Tomaz Kotnik, Lidija Slemenik Pers, Ema Zagar, Boris Saje, Kristina Zuzek, Saso Sturm
Summary: This study describes the fabrication of SrFe12O19-based filaments using PPS as the binder and the subsequent printing of these filaments with a 3D printer. The presence of a magnetic field during printing was found to improve the magnetic properties of the printed magnets by enhancing the magnetic texture.
JOURNAL OF MAGNETISM AND MAGNETIC MATERIALS
(2023)
Article
Engineering, Mechanical
S. Matkovic, M. Bek, M. Kalin
Summary: In this study, we evaluated the tribological performance of polypropylene composites with wood-flour fillers obtained as a by-product from the wood-processing industry. The addition of wood fillers significantly improved the tribological performance of the composites compared to neat polypropylene materials, reducing friction coefficient and improving wear resistance. The use of wood fillers could compensate for the poorer properties of recycled materials, making the polypropylene-wood composites a suitable sustainable choice for tribological applications.
Proceedings Paper
Materials Science, Multidisciplinary
Roland Kadar, Ann Terry, Kim Nygard, Tiina Nypelö, Gunnar Westman, Sylwia Wojno, Reza Ghanbari, Mina Fazilati, Marko Bek, Amit Kumar Sonker
Summary: Hierarchical biomaterials play a crucial role in developing sustainable novel material systems. The challenge lies in controlling their assembly into hierarchical orders at different scales, especially in understanding the orientation dynamics. This study focuses on water-based suspensions of cellulose nanocrystals, but the findings can be applied to other nanostructured fluids as well.
NOVEL TRENDS IN RHEOLOGY IX
(2023)
Article
Nanoscience & Nanotechnology
Hengzhi Ruan, Marko Bek, Santosh Pandit, Alexandra Aulova, Jian Zhang, Philip Bjellheim, Martin Lovmar, Ivan Mijakovic, Roland Kadar
Summary: This study presents a facile approach of incorporating dopamine and [2-(methacryloyloxy) ethyl] dimethyl-(3-sulfopropyl) ammonium hydroxide via in situ synthesis into gelatin hydrogels. The resulting hydrogels show exceptional antibacterial efficiency and multifunctional performance, making them highly promising for various biomedical applications.
ACS APPLIED MATERIALS & INTERFACES
(2023)
Article
Materials Science, Ceramics
Milan Vuksic, Marko Bek, Lidija Slemenik Perse, Marjeta Macek Krzmanc, Andraz Kocjan, Aljaz Ivekovic
Summary: Fused filament fabrication (FFF) is a versatile and inexpensive AM technique for fabricating complex ceramic structures. The addition of paraffin wax (PW) resulted in the successful fabrication of flexible filaments, but had no significant impact on debinding.
