Understanding the dynamic behavior of rubber materials
Researchers present a novel experimental system for simultaneous measurement of dynamic mechanical properties and X-ray computed tomography
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THIS NOVEL SYSTEM CAN ELUCIDATE THE MICROSTRUCTURE OF RUBBER-LIKE MATERIALS UNDER DYNAMIC CONDITIONS, ENHANCING OUR UNDERSTANDING OF THEIR DYNAMIC BEHAVIOR AND PAVING THE WAY FOR IMPROVED NOVEL MATERIALS.
view moreCREDIT: MASAMI MATSUBARA FROM WASEDA UNIVERSITY
Rubber-like materials, commonly used in dampeners, possess a unique property known as dynamic viscoelasticity, enabling them to convert mechanical energy from vibrations into heat while exhibiting spring-like and flow-like behaviors simultaneously. Customization of these materials is possible by blending them with compounds of specific molecular structures, depending on the dynamic viscosity requirements.
However, the underlying mechanisms behind the distinct mechanical properties of these materials remain unclear. A primary reason for this knowledge gap has been the absence of a comprehensive system capable of simultaneously measuring the mechanical properties and observing the microstructural dynamics of these materials. While X-ray computed tomography (CT) has recently emerged as a promising option for a non-destructive inspection of the internal structure of materials down to nano-scale resolutions, it is not suited for observation under dynamic conditions.
Against this backdrop, a team of researchers, led by Associate Professor (tenure-track) Masami Matsubara from the School of Creative Science and Engineering at the Faculty of Engineering at Waseda University in Japan, has now developed an innovative system that can conduct dynamic mechanical analysis and dynamic micro X-ray CT imaging simultaneously. Their study was made available online on October 19, 2023 and will be published in Volume 205 of the journal Mechanical Systems and Signal Processing on December 15, 2023.
"By integrating X-ray CT imaging performed at the large synchrotron radiation facility Spring-8(BL20XU) and mechanical analysis under dynamic conditions, we can elucidate the relationship between a material's internal structure, its dynamic behavior, and its damping properties," explains Dr. Matsubara. At the core of this novel system is the dynamic micro X-ray CT and a specially designed compact shaker developed by the team that is capable of precise adjustment of vibration amplitude and frequency.
The team utilized this innovative system to investigate the distinctions between styrene-butadiene rubber (SBR) and natural rubber (NR), as well as to explore how the shape and size of ZnO particles influence the dynamic behavior of SBR composites.
The researchers conducted dynamic micro X-ray CT scans on these materials, rotating them during imaging while simultaneously subjecting them to vibrations from the shaker. They then developed histograms of local strain amplitudes by utilizing the local strains extracted from the 3D reconstructed images of the materials’ internal structures. These histograms, in conjunction with the materials' loss factor, a measure of the inherent damping of a material, were analyzed to understand their dynamic behavior.
When comparing materials SBR and NR, which have significantly different loss factors, the team found no discernible differences between their local strain amplitude histograms. However, the histograms displayed wider strain distributions in the presence of composite particles like ZnO. This suggests that strain within these materials is non-uniform and depends on the shape and size of the particles, which may have masked any changes from the addition of the particles.
“This technology can allow us to study the microstructure of rubber and rubber-like materials under dynamic conditions and can result in the development of fuel-efficient rubber tires or gloves that do not deteriorate. Moreover, this technology can also enable the dynamic X-ray CT imaging of living organs that repeatedly deform, such as the heart, and can even pave the way for the development of artificial organs,” says Dr. Matsubara, highlighting the importance of this study.
Overall, this breakthrough technology has the potential to advance the understanding of the microstructure of viscoelastic materials, likely opening the doors for the development of novel materials with improved properties.
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Reference
DOI: https://doi.org/10.1016/j.ymssp.2023.110875
Authors: Masami Matsubara1, Ryo Takara2, Taichi Komatsu2, Shogo Furuta2, Khoo Pei Loon2, Masakazu Kobayashi2, Hitomu Mushiaki3, Kentaro Uesugi4, Shozo Kawamura2, and Daiki Tajiri2
Affiliations
1Department of Modern Mechanical Engineering, Waseda University
2Department of Mechanical Engineering, Toyohashi University of Technology
3Hyogo Prefectural Institute of Technology
4Japan Synchrotron Radiation Research Institute
About Waseda University
Located in the heart of Tokyo, Waseda University is a leading private research university that has long been dedicated to academic excellence, innovative research, and civic engagement at both the local and global levels since 1882. The University has produced many changemakers in its history, including nine prime ministers and many leaders in business, science and technology, literature, sports, and film. Waseda has strong collaborations with overseas research institutions and is committed to advancing cutting-edge research and developing leaders who can contribute to the resolution of complex, global social issues. The University has set a target of achieving a zero-carbon campus by 2032, in line with the Sustainable Development Goals (SDGs) adopted by the United Nations in 2015.
To learn more about Waseda University, visit https://www.waseda.jp/top/en
About Associate Professor Masami Matsubara
Masami Matsubara is an Associate Professor (tenure-track) at the School of Creative Science and Engineering of the Faculty of Science and Engineering at Waseda University, Japan. He earned his Ph.D. from Doshisha University. His research focuses on the mechanics of materials, mechatronics, and dynamic modelling. He has recently worked on vibration reduction methods and dynamic design for large-scale numerical analysis models and detailed design and experimental methods for component and unit testing. He is a member of the Japan Society of Mechanical Engineers (JSME) and SAE International. He received the JSME Medal for Outstanding Paper in 2014, 2020, and 2022.
JOURNAL
Mechanical Systems and Signal Processing
METHOD OF RESEARCH
Imaging analysis
SUBJECT OF RESEARCH
Not applicable
ARTICLE TITLE
In-situ measurement of dynamic micro X-ray CT and dynamic mechanical analysis for rubber materials
Cheap and efficient ethanol catalyst from laser-melted nanoparticles
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SUCCESSIVE PHASES OF AGGLOMERATION OF NANOPARTICLES OF COPPER AND ITS OXIDES, OCCURRING IN THE FIRST 200 PICOSECONDS OF LASER MELTING: TOP IN MICROSCOPIC IMAGES (MAG. 50000X), BOTTOM IN COMPUTER SIMULATION.
view moreCREDIT: SOURCE: IFJ PAN
Cracow, 8 November 2023
Cheap and efficient ethanol catalyst from laser-melted nanoparticles
Ethanol fuel cells are regarded as promising sources of green electricity. However, expensive platinum catalysts are used in their production. Research on laser melting of suspensions, carried out at the Institute of Nuclear Physics of the Polish Academy of Sciences in Cracow, has led researchers to materials that catalyse ethanol with a similar – and potentially even greater – efficiency to platinum, yet are made of an element that is many times cheaper than platinum.
When a suspension of nanoparticles is irradiated by laser pulses, the particles in the suspension can begin to melt and stick together permanently, while rapidly undergoing chemical reactions that are more or less complex. One of the recent materials obtained in this way, produced at the Institute of Nuclear Physics of the Polish Academy of Sciences (IFJ PAN) in Cracow, turns out to have an unexpectedly high efficiency in catalysing ethanol, a compound considered to be a promising energy source for fuel cells.
Ethanol is a fuel with many advantages – it can be produced in a renewable manner (for example, from biomass), it can be easily stored as well as having low toxicity. What is of particular importance, however, is the fact that up to several times the amount of electricity can be obtained from a unit mass of ethanol compared to current popular power sources.
Electricity in ethanol-powered fuel cells is generated by processes associated with the oxidation of this alcohol on the catalyst layer of the reaction. Unfortunately, current catalysts do not allow the rapid and complete oxidation of ethanol to water and carbon dioxide. As a result, the cells not only fail to reach maximum efficiency, but also produce undesirable by-products that are deposited on the catalyst and, over time, lead to the disappearance of its properties.
“A considerable obstacle to the commercial success of ethanol cells is also their price. The catalyst we have found can have a significant impact on its reduction and, consequently, on the availability of new cells on the consumer market. This is because its main component is not platinum, but copper, which is almost 250 times cheaper than platinum,” says Dr. Mohammad Shakeri (IFJ PAN), first author of the paper in the journal Advanced Functional Materials.
The achievement of scientists from the IFJ PAN is the result of research conducted on laser control of the size and chemical composition of agglomerates in suspensions. The main idea behind the laser nanosynthesis of composites is the irradiation of a suspension containing agglomerates of nanoparticles of a specific chemical substance with pulses of unfocused laser light with appropriately selected parameters. The aptly delivered energy causes the temperature of the particles to increase, they melt on the surface and clump together into larger and larger structures, which cool rapidly on contact with the surrounding cool liquid. The temperature reached by the particles is determined by many factors, including the energy of the photons emitted by the laser, the intensity of the beam, the frequency and length of the pulses, and even the size of the agglomerates in suspension.
“Depending on the temperature reached by the agglomerates, various chemical reactions may take place in the material in addition to changes of a purely structural nature. In our research, we focused on the most accurate theoretical and experimental analysis of the physical and chemical phenomena in suspensions in which pulses of laser light were absorbed by nanoparticles of copper and its oxides,” explains Dr. Zaneta Swiatkowska-Warkocka (IFJ PAN).
In the case of real solution particles, the temperature rise occurs in nanoseconds, too rapidly to be measured. In this situation, theoretical molecular dynamics analyses became the first step in understanding the copper systems under study, supported at later stages by simulations performed by the Prometheus computer cluster from Cracow. Thanks to these, the researchers determined to what temperatures the agglomerates of various sizes would heat up and what compounds might form in these processes. In addition, they checked whether these compounds would be thermodynamically stable or undergo further transformations. The physicists used the knowledge gained to prepare a series of experiments in which nanoparticles of copper and its oxides were laser fused in various proportions.
The composite materials obtained were tested in the laboratories of the IFJ PAN and in the Cracow SOLARIS cyclotron, among others, to determine the degree of oxidation of copper compounds. The information obtained allowed the researchers to identify the optimum catalyst. This turned out to be a three-component system built from appropriate proportions of copper and its oxides of the first and second oxidation state (i.e. Cu2O and CuO).
“From the point of view of efficiency of ethanol catalysis, the crucial discovery was that particles of copper oxide Cu2O3, which is usually thermodynamically very unstable, were present in our material. On one hand, they are characterised by an extremely high degree of oxidation, on the other hand, we found them mainly on the surface of the Cu2O particles, which in practice means that they had very good contact with the solution. It is these Cu2O3 particles that facilitate the adsorption of the alcohol molecules and the breaking of the carbon-hydrogen bonds in them,” states Dr. Shakeri.
Tests on the properties of the catalyst produced by the Cracow physicists ended with optimistic results. The selected composite retained the ability to fully oxidise ethanol even after several hours of use. Moreover, its electrocatalytic efficiency proved comparable to that of contemporary platinum catalysts. From a scientific perspective, this result is positively astonishing. Catalysis generally proceeds more efficiently the larger the surface area of the agglomerates, which has to do with the fragmentation of their structure. However, the composite studied was not nanometre in size, but several orders of magnitude larger, submicron in size. It seems likely, therefore, that if physicists succeed in reducing the size of the particles in the future, the efficiency of the new catalyst could increase still further.
The work on laser fusion of copper nanostructures was funded by the Polish National Science Centre.
The Henryk Niewodniczański Institute of Nuclear Physics (IFJ PAN) is currently one of the largest research institutes of the Polish Academy of Sciences. A wide range of research carried out at IFJ PAN covers basic and applied studies, from particle physics and astrophysics, through hadron physics, high-, medium-, and low-energy nuclear physics, condensed matter physics (including materials engineering), to various applications of nuclear physics in interdisciplinary research, covering medical physics, dosimetry, radiation and environmental biology, environmental protection, and other related disciplines. The average yearly publication output of IFJ PAN includes over 600 scientific papers in high-impact international journals. Each year the Institute hosts about 20 international and national scientific conferences. One of the most important facilities of the Institute is the Cyclotron Centre Bronowice (CCB), which is an infrastructure unique in Central Europe, serving as a clinical and research centre in the field of medical and nuclear physics. In addition, IFJ PAN runs four accredited research and measurement laboratories. IFJ PAN is a member of the Marian Smoluchowski Kraków Research Consortium: “Matter-Energy-Future”, which in the years 2012-2017 enjoyed the status of the Leading National Research Centre (KNOW) in physics. In 2017, the European Commission granted the Institute the HR Excellence in Research award. As a result of the categorization of the Ministry of Education and Science, the Institute has been classified into the A+ category (the highest scientific category in Poland) in the field of physical sciences.
SCIENTIFIC PUBLICATIONS:
“Alternative Local Melting-Solidification of Suspended Nanoparticles for Heterostructure Formation Enabled by Pulsed Laser Irradiation”
M. S. Shakeri, Ż. Świątkowska-Warkocka, O. Polit, T. Itina, A. Maximenko, J. Depciuch, J. Gurgul, M. Mitura-Nowak, M. Perzanowski, A. Dziedzic, J. Nęcki
Advanced Functional Materials, 33, 43, 2023
LINKS:
The website of the Institute of Nuclear Physics, Polish Academy of Sciences.
Press releases of the Institute of Nuclear Physics, Polish Academy of Sciences.
IMAGES:
IFJ231108b_fot01s.jpg
HR: http://press.ifj.edu.pl/news/2023/11/08/IFJ231108b_fot01.jpg
Successive phases of agglomeration of nanoparticles of copper and its oxides, occurring in the first 200 picoseconds of laser melting: top in microscopic images (mag. 50000x), bottom in computer simulation. (Source: IFJ PAN)
MOVIES:
Simulation of laser melting of nanoparticles
https://www.youtube.com/watch?v=pcUKtqFpLqM
Simulation of laser melting of nanoparticles made of copper and its oxides. (Source: IFJ PAN)
JOURNAL
Advanced Functional Materials
ARTICLE TITLE
Alternative Local Melting-Solidification of Suspended Nanoparticles for Heterostructure Formation Enabled by Pulsed Laser Irradiation
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