Quantum dots (QDs) have sparked great interest due to their unique electronic, optical, and structural properties. In this review, we provide a critical analysis of the latest advances in the synthesis, properties, and applications of QDs. We discuss synthesis techniques, including colloidal and hydrothermal synthesis, and highlight how the underlying principles of these techniques affect the resulting properties of QDs. We then delve into the wide range of applications of QDs, from QDs based color conversion, light-emitting diodes and biomedicine to quantum-based cryptography and spintronics. Finally, we identify the current challenges and future prospects for quantum dot research. By reading this review, readers will gain a deeper understanding of the current state-of-the-art in QDs research and the potential for future development.
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Kushagra Agarwal et al 2023 Mater. Res. Express 10 062001
William Xaveriano Waresindo et al 2023 Mater. Res. Express 10 024003
Hydrogel is being broadly studied due to their tremendous properties, such as swelling behavior and biocompatibility. Numerous review articles have discussed hydrogel polymer types, hydrogel synthesis methods, hydrogel properties, and hydrogel applications. Hydrogel can be synthesized by physical and chemical cross-linking methods. One type of the physical cross-linking method is freeze-thaw (F–T), which works based on the crystallization process of the precursor solution to form a physical cross-link. To date, there has been no review paper which discusses the F–T technique specifically and comprehensively. Most of the previous review articles that exposed the hydrogel synthesis method usually mentioned the F–T process as a small part of the physical cross-linking method. This review attempts to discuss the F–T hydrogel specifically and comprehensively. In more detail, this review covers the basic principles of hydrogel formation in an F–T way, the parameters that influence hydrogel formation, the properties of the hydrogel, and its application in the biomedical field.
Ahmad Y Al-Maharma et al 2020 Mater. Res. Express 7 122001
In the present review, the effect of porosity on the mechanical properties of the fabricated parts, which are additively manufactured by powder bed fusion and filament extrusion-based technologies, are discussed in detail. Usually, additive manufacturing (AM) processes based on these techniques produce the components with a significant amount of pores. The porosity in these parts typically takes two forms: pores with irregular shapes (called keyholes) and uniform (spherical) pores. These pores are present at different locations, such as surface, sub-surface, interior bulk material, between the deposited layers and at filler/matrix interface, which critically affect the corrosion resistance, fatigue strength, stiffness, mechanical strength, and fracture toughness properties, respectively. Therefore, it is essential to study and understand the influence of pores on the mechanical properties of AM fabricated parts. The technologies of AM can be employed in the manufacturing of components with the desired porous structure through the topology optimization process of scaffolds and lattices to improve their toughness under a specific load. The undesirable effect of pores can be eliminated by using defects-free raw materials, optimizing the processing parameters, and implementing suitable post-processing treatment. The current review grants a more comprehensive understanding of the effect of porous defects on mechanical performance and provides a mechanistic basis for reliable applications of additively manufactured components.
Yangang Li et al 2022 Mater. Res. Express 9 122001
Two-dimensional (2D) transition metal dichalcogenides (TMDs) have attracted extensive attraction due to their unique properties in novel physical phenomena, such as superconductors, Moiré superlattices, ferromagnetics, Weyl semimetals, which all require the high quality of 2D TMDs. Mechanical exfoliation (ME) as a top-down strategy shows great potential to obtain 2D TMDs with high quality and large scale. This paper reviews the theoretical and experimental details of this method. Subsequently, diverse modified ME methods are introduced. Significantly, the recent progress of the Au-assisted ME method is the highlight. Finally, this review will have an insight into their advantages and limitations, and point out a rational direction for the exfoliation of TMDs with high quality and large size.
Badrut Tamam Ibnu Ali et al 2022 Mater. Res. Express 9 125302
The selection of the solvent during the membrane preparation process significantly affects the characteristics of the resulting membrane. The large number of organic solvents available for dissolving polymers renders this experimental approach ineffective. A computational approach can select a solvent using the solvation energy value approach. In addition, no organic waste is generated from the computational approach, which is a distinct advantage. A computational approach using the DFT/B3LYP/def2-TZVP RIJCOSX method was used to optimize the structure of polyethylene terephthalate (PET). The PET for the experiment was obtained from the utilization of plastic bottle waste. In addition, a review of the thermodynamics, geometry, HOMO-LUMO orbitals, and vibrational frequencies was conducted to validate the PET molecule against the experimental results. A conductor-like polarizable continuum model was used to determine the best solvent for dissolving the PET plastic waste. The results demonstrated that the Fourier Transform Infra-Red and Fourier Transform Raman spectra obtained from computational calculations were not significantly different from the experimental results. Based on a thermodynamic approach, computationally the Gibbs free energy (−724.723), entropy (0.0428), and enthalpy (−724,723 Kjmol−1 ) values of the PET dimer molecule are not much different from the experimental values (−601, 0.042, and −488 Kjmol−1). The computational approach was successful in selecting solvents that can dissolve PET plastic bottle waste. Phenol solvent has the lowest solvation energy value (−101.879 Kjmol−1) and the highest binding energy (2.4 Kjmol−1) than other solvents. Computational and experimental results demonstrated that the phenol solvent was able to dissolve PET plastic bottle waste better than the other solvents.
Jianxin Wu et al 2022 Mater. Res. Express 9 032001
Aluminum and its alloys having lots of advantageous properties are among the most-used metallic materials. So, it is of immense importance to find suitable processes and methods leading to high-quality purified Al melt. In this regard, there are numerous challenges in achieving high purity Al melts, such as its propensity to react with air, oxygen, and water vapor, the presence of a variety of oxide, non-oxide, and solid particle inclusions that lead to the production of pores, cracks, pinholes, and dross, finally adversely influencing the overall quality of the product. The main methods of melt refining are fluxing, floatation, and filtration, but more sophisticated methods have also emerged. The best method for purification can be chosen based on the type of impurities and the desired level of purification. With the industrial development, the need to establish more cost-effective and simpler methods has increased, and in addition, methods should be considered for recycling large volumes of scarp Al parts that contain more impurities. Moreover, achieving high purity melt is also a vital issue for use in specific applications. The present article has been written to discuss the above issues and focus on the study of various methods of aluminum purification.
Muhammad Hafeez et al 2020 Mater. Res. Express 7 025019
Cobalt oxide nanoparticles (Co3O4-Nps) have many applications and now a days the green methods of synthesis of these NPs are preferred over other methods because of associated benefits. In this study, Co3O4-Nps were synthesized by using leaves extract of Populus ciliata (safaida) and cobalt nitrate hexa hydrate as a source of cobalt. The synthesized NPs were analyzed by different techniques such as fourier transform spectroscopy (FTIR), x-ray diffraction (XRD), transmission electron microscopy (TEM) and scanning electron microscopy (SEM). Antibacterial activities of the synthesized Co3O4-Nps were evaluated against gram negative and gram positive bacteria and found active against Escherichia coli (E. coli), Klebseilla pneumonia (K. pneumonia), Bacillus subtillus (B.subtillus) and Bacillus lichenifermia (B. lichenifermia). The activity results were analyzed statistically by one-way ANOVA, with 'Dunnett's Multiple Comparison Test'. The maximum mean activity (21.8 ± 0.7) was found for B. subtilis and minimum mean activity (14.0 ± 0.6) was observed for E. coli.
Mariela Flores-Castañeda et al 2024 Mater. Res. Express 11 055005
This study presents a simple two-step synthesis method for the fabrication of Ag/ZnO nanocomposites to improve the photocatalytic response of ZnO. The synthesis involves ZnO nanoparticles that were fabricated from the thermal decomposition of commercial zinc acetate. In order to produce Ag/ZnO nanoparticles in a simple two-step process, ZnO nanoparticles were mixed with Ag nanoparticle suspensions previously obtained by the laser ablation of solids in liquids technique at three different fluences. Structural characterization of ZnO powders revealed the presence of single phase wurtzite ZnO nanoparticles with crystal sizes of 20 nm. On the other hand, XRD patterns for a composite sample revealed the presence of signals associated to both ZnO and Ag suggesting that silver nanoparticles were attached to the ZnO particles surface. Optical characterization of the ZnO powders, carried out by UV–vis spectroscopy, showed a strong absorption band centered at 380 nm, which is associated to excitonic transitions in ZnO nanoparticles, whilst absorption measurements of silver nanoparticles colloids revealed the presence of a strong band centered near 412 nm. This band shifts to shorter wavelengths with increasing fluence from 2.6 to 6.2 J cm−2, indicating changes in nanoparticles size. Photocatalytic degradation tests of methylene blue under UV irradiation were carried out using pure ZnO, Ag colloids and Ag/ZnO nanoparticles. After the first 30 min of irradiation, it was observed that the silver nanoparticles reached degradation percentages of 16, 22 and 29% for samples synthesized at 2.6, 4.2 and 6.2 J cm−2, respectively. Meanwhile the ZnO sample reached a value of 13% after 30 min. Regarding the Ag/ZnO composite sample, the percentage of degradation after 30 min was 36%, demonstrating a considerable enhanced photocatalytic activity as compared to ZnO. After 24 h irradiation, Ag/ZnO degraded 95% of the methylene blue solution. It was observed that decorating ZnO with laser produced silver nanoparticles accelerates the photocatalytic response of ZnO by enhancing the activity at short times.
Ruby Garg et al 2020 Mater. Res. Express 7 022001
To meet the energy needs batteries and supercapacitors are evolved as a promising candidate from the class of energy storage devices. The growth in the development of new 2D electrode materials brings a new revolution in energy storage devices with a comprehensive investigation. MXene, a new family of 2D metal carbides, nitrides and carbonitrides due to their attractive electrical and electrochemical properties e.g. hydrophilicity, conductivity, surface area, topological structure have gained huge attention. In this review, we discussed different MXene synthesis routes using different etchants e.g. hydrofluoric acid, ammonium hydrazine, lithium fluoride, and hydrochloric acid, etc showing that fluorine formation is compulsory to etch the aluminum layer from its precursor. Due to the advantage of large interlayer spacing between the MXene layers in MXene, the effect of intercalation on the performance of batteries and supercapacitors using MXene as electrodes by various sized cations are reviewed. Different MXene hybrids as supercapacitor electrodes will also be summarized. Lastly, the conclusion and future scope of MXene to be done in various supercapacitor applications are also presented.
Xi Huang et al 2020 Mater. Res. Express 7 066517
The oxidation behavior of 316L stainless steel exposed at 400, 600 and 800 °C air for 100, 500 and 1000 h was investigated using different characterization techniques. Weight gain obeys a parabolic law, but the degree of deviation of n index is increasingly larger with the increase of temperature. A double oxide film, including Cr2O3 and Fe2O3 oxide particles in outer and FeCr2O4 oxides in inner, is observed at 400 °C. As regards to samples at 600 °C, a critical exposure period around 100 h exists in the oxidation process, at which a compact oxide film decorated with oxide particles transforms to a loose oxide layer with a pore-structure. In addition, an oxide film containing Fe-rich outer oxide layer and Cr-rich inner oxide layer is observed at 600 °C for 500 and 1000 h. Spallation of oxide scale is observed for all samples at 800 °C regardless of exposure periods, resulting in different oxidation morphologies, and the degree of spallation behavior is getting worse. A double oxide film with the same chemical composition as 600 °C is observed, and the thickness increases over exposure periods.
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Seiichi Urakawa et al 2024 Mater. Res. Express 11 065901
ZnO–AlN pseudo-binary amorphous alloys (a-ZAON hereinafter) with tunable band gaps in the deep ultraviolet (DUV) region have been synthesized using magnetron sputtering. The miscibility gap between ZnO and AlN has been overcome using room-temperature sputtering deposition, leveraging the rapid quenching abilities of sputtered particles to fabricate metastable but single-phase alloys. X-ray diffraction patterns and optical transmittance spectra revealed that the synthesized films with chemical composition ratios of [Zn]/([Zn] + [Al]) = 0.24–0.79 likely manifested as single-phase of a-ZAON films. Despite their amorphous structures, these films presented direct band gaps of 3.4–5.8 eV and thus high optical absorption coefficients (105 cm−1). Notably, the observed values adhered to Vegard's law for crystalline ZnO–AlN systems, implying that the a-ZAON films were solid solution alloys with atomic-level mixing. Furthermore, atomic force microscopy analyses revealed smooth film surfaces with root-mean-square roughness of 0.8–0.9 nm. Overall, the wide-ranging band gap tunability, high absorption coefficients, amorphous structures, surface smoothness, and low synthesis temperatures of a-ZAON films position them as promising materials for use in DUV optoelectronic devices and power devices fabricated using large-scale glass and flexible substrates.
Venkatesh R et al 2024 Mater. Res. Express 11 066505
The effectiveness of turning processes in manufacturing depends on the efficiency of cutting tool inserts. Coating these inserts is one common method that has been used to prolong their life span, reduce friction and increase wear resistance. The main purpose of the present study was to enhance the efficiency of turning tool inserts by exploring different combinations of coating substances such as TiAlN, AlCrN, and TiAlN/AlCrN. Cutting speed, feed rate, cutting depth and type of coating material were important input parameters for optimization. It was observed that tools with coatings like TiAIN and AlCrN had higher performance than those with single-layered ones. The use of multilayer coated inserts comprising TiAlN/AlCrN increased the hardness but reduced the wear thereby enhancing machining effectiveness. For Taguchi Grey Relation Analysis (GRA) optimization technique with L27 array for hardness and flank wear output parameters aimed at enhancement of input process parameters in turning operations. The coatings crystalline structure, phase composition and other crucial details for their performance were analyzed using Energy Dispersive (EDS) Spectroscopy and Scanning Electron (SEM) Microscopy techniques. The TiAlN/AlCrN coatings showed greater machinability than those with only TiAlN or AlCrN, even at high spindle speeds. The best processes were identified using the Taguchi and Grey relational optimization techniques. Some of these parameters include a speed of 600 m min−1, a feed rate of 0.10 mm rev−1, a depth of 1.5 mm, and a TiAlN/AlCrN coating. This meant that the hardness was at 3772 HV while flank wear is 6.45 mm for optimum parameters among others obtained from experiments. The Grey relation analysis results demonstrated significant improvement in grade indicating the good performance of selected parameters. Various relationships can be displayed using contour plots which are usually visual representation between several factors in an experiment such as hardness and wear resistance which is shown by multilayer coating compared to single-layer coatings.
Shan Su et al 2024 Mater. Res. Express 11 066504
The composite structure of aluminium alloy and stainless steel provides a wide range of comprehensive advantages, encompassing properties such as lightweight, high strength, and corrosion resistance. These advantages make composite structure particularly suitable for various applications in industries such as transportation and chemicals. One innovative solid-phase welding technology that is well suited for joining dissimilar materials is vaporizing foil actuator welding. This technology allows for the welding of composite structures made of aluminium and stainless steel, despite the significant differences in physical and chemical properties. To enhance the vaporizing welding process, this paper proposes the introduction of an interlayer between the dissimilar materials. The interlayer consists of a third material that is added to bridge the gap between materials with differing hardness and plasticity. The main objective of introducing the interlayer is to minimise performance disparities and reduce the formation of intermetallic compounds at the interface. By examining the vaporizing foil actuator welding process of aluminium alloy and stainless steel with the interlayer, it aims to analyse the characteristics of the interface morphology. Additionally, this study investigates the energy conversion mechanism of the aluminium foil gasification process and explore the influence of the interlayer on the microstructure and mechanical properties of the interface between aluminium alloy and stainless-steel joints.
Sugumaran B and Ibsa Neme 2024 Mater. Res. Express 11 065503
This study seeks to investigate the influence of cement and Arabic gum on the physico-mechanical and microstructural properties of cementitious composites. The influence of varying quantities of Arabic gum on the hydration, fluidity, mechanical performance and microstructure of cement paste was investigated. The influence of Arabic gum on slant shear performance and capillary water absorption was also investigated. The results indicate that the workability of cement was diminished as a result of the ability of Arabic gum to make the cement paste cohesive. It is evident that when the gum Arabic concentration increases from 147 to 174 mm, the resultant slump value for various w/b ratios drops. The adsorption characteristics showed that for a 15 mg g−1 dosage at 60, 45, 30, and 15 min, respectively, 1.43, 1.32, 1.25, and 1.03 mg g−1 are achieved. For 1% gum Arabic substitution, the highest flexural strength percentage growth is achieved at 38.46%, 23.74%, and 17.29% at 7, 14, and 28 days, respectively. In addition, the inclusion of Arabic gum improved the slant shear strength of cement composite, making it ideal for use as a building repair material with significant application potential. Experiments on the bonding behavior of the produced cementitious composite with the old mortar reveal that the shear bond strength was greatly increased, demonstrating the compatibility between the old and new cement composites. The microstructure and the porosity of the cement matrix also showed denser and compact matrix making them durable to attain better service life.
Jingcheng Wang et al 2024 Mater. Res. Express 11 062001
The mixing process is a critical step in the production of energetic materials and has a profound impact on product performance. As modern formulations for energetic materials continue to advance, the needs placed on the mixing process have become increasingly complex. Understanding and mastering the properties of the mixing flow field are essential for achieving optimal mixing function, ensuring process safety, and optimizing the parameters of both the mixing process and equipment specifically for energetic materials. In this comprehensive review, we analyze the influence of flow field properties on the mixing process of energetic materials by examining the mixing mechanism of two types of flow within the flow field. Additionally, we provide evidence to support the advantages of elongational flow in achieving effective mixing. We also discuss the application of mixing flow field properties in the processing of energetic materials, including advancements in mixing equipment and methods designed to optimize flow fields. Finally, we address the current shortcomings in energetic material mixing and offer an outlook for future developments in this field.
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Jingcheng Wang et al 2024 Mater. Res. Express 11 062001
The mixing process is a critical step in the production of energetic materials and has a profound impact on product performance. As modern formulations for energetic materials continue to advance, the needs placed on the mixing process have become increasingly complex. Understanding and mastering the properties of the mixing flow field are essential for achieving optimal mixing function, ensuring process safety, and optimizing the parameters of both the mixing process and equipment specifically for energetic materials. In this comprehensive review, we analyze the influence of flow field properties on the mixing process of energetic materials by examining the mixing mechanism of two types of flow within the flow field. Additionally, we provide evidence to support the advantages of elongational flow in achieving effective mixing. We also discuss the application of mixing flow field properties in the processing of energetic materials, including advancements in mixing equipment and methods designed to optimize flow fields. Finally, we address the current shortcomings in energetic material mixing and offer an outlook for future developments in this field.
Qiaoqiao Lan et al 2024 Mater. Res. Express 11 052001
Bio-based polyurethanes are novel material with potential advantages for sustainable development, and their development play significant roles in promoting sustainability. Curcumin, a natural monomer, possesses high biological activity and features a symmetrical chemical structure with various functional groups such as phenolic hydroxyl, carbonyl and benzene ring. The presence of hydroxyl groups in the structure of curcumin provides essential conditions for its involvement in polyurethane synthesis. This review article provides an overview of the applications of curcumin as a chain extender, crosslinking agent and end-capper in polyurethanes, as well as its effects on the chemical structure, mechanical properties, and chemical stability of polyurethanes. Furthermore, the functional applications of curcumin-based polyurethanes in various fields such as medicine, food packaging, and coatings are discussed. Finally, considering the current research status and inherent properties of curcumin, the future prospects of curcumin-based polyurethanes are contemplated.
Tao Huang et al 2024 Mater. Res. Express 11 032003
As a kind of special energy field assisted plastic forming, electric pulse assisted plastic forming combines multiple physical fields, such as thermal, electrical, magnetic and mechanical effects, has multiple effects on metal. It has a good industrial application prospect in the fields of directional microstructure regulation of materials and preparation of new materials. The flow stress of metal materials can be effectively reduced by electro-pulse assisted forming. The action mechanism of pulse current includes thermodynamics (Joule heating effect) and kinetic (pure electro-plastic effect or athermal effect). Thermodynamically, electric pulses can be used to provide the energy for dislocation migration and atomic diffusion, and aid in microstructure changes such as recrystallization, phase transition and microcrack healing of metals. In terms of dynamics, electric pulse has an effect on the speed and path of dislocation structure evolution. On this basis, a series of theoretical models for accurately predicting the flow stress of materials in electrically assisted forming process were formulated by combining the stress–strain constitutive relationship considering the temperature rise effect and the pure electro-plastic effect. The accuracy of the predicting model is greatly enhanced by the introduction of electrical parameters. The mechanism for electrically assisted forming was further revealed.
Ane Lasa et al 2024 Mater. Res. Express 11 032002
All plasma facing surfaces in a fusion reactor, whether initially pure or an alloy, will rapidly evolve into a mixed material due to plasma-induced erosion, migration and redeposition. Beryllium (Be) erosion from the main chamber, and its transport and deposition on to a tungsten (W) divertor results in the growth of mixed Be-W layers, which can evolve to form beryllides. These Be-W mixed materials exhibit generally less desirable properties than pure tungsten or pure beryllium, such as lower melting points. In order to better understand the parameter space for growth of these alloys, this paper reviews the literature on Be-W mixed material formation experiments—in magnetically confined fusion reactors, in linear plasma test stands, and during thin-film deposition—and on computational modeling of Be-W interactions, as well as briefly assesses the Be-W growth kinetics. We conclude that the following kinetic steps drive the material mixing: adsorption of the implanted/deposited ion on the metal surface; diffusion of the implanted/deposited ion from surface into the bulk, which is accelerated by defects; and loss of deposited material through erosion. Adsorption dominates (or prevents) material mixing in thin-film deposition experiments, whereas diffusion drives material mixing in plasma exposures due to the energetic ion implantation.
Meng Xu et al 2024 Mater. Res. Express 11 032001
Heavy metal ions and organic pollutants cause irreversible damage to water environment, thereby posing significant threats to the well-being of organisms. The techniques of adsorption and photocatalytic degradation offer versatile solutions for addressing water pollution challenges, attributed to their inherent sustainability and adaptability. Silicates exhibit exceptional practicality in the realm of environmental protection owing to their structural integrity and robust chemical/thermal stability during hybridization and application process. Furthermore, the abundance of silicate reserves, coupled with their proven effectiveness, has garnered significant attention in recent years. This detailed review compiles and analyzes the extensive body of literature spanning the past six years (2018–2023), emphasizing the pivotal discoveries associated with employing silicates as water purification materials. This review article provides a comprehensive overview of the structure, classification, and chemical composition of diverse silicates and offers a thorough descriptive analysis of their performance in eliminating pollutants. Additionally, the utilization of diatomite as either precursors or substrates for silicates, along with the exploration of their corresponding purification mechanisms is discussed. The review unequivocally verifies the efficiency of silicates and their composites in the effective elimination of various toxic pollutants. However, the development of novel silicates capable of adapting to diverse environmental conditions to enhance pollution control, remains an urgent necessity.
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Bao et al
The physical mixing of inorganic fillers and a polymer matrix is a common method for constructing superhydrophobic coatings. Nevertheless, the interface bonding strength between the polymer and nanofiller was weak. The construction of interacting covalent bonds is a potential solution. In this study, carbon nanotubes were modified by aminopropyltriethoxysilane (APTES) and fluorosilane, and the reaction between the amino groups in APTES and -NCO(curing agent N3390) improved the bonding strength. Thus, the coatings maintained superhydrophobicity even after 260 abrasion cycles, 200 tape-peeling cycles, 18-day heat treatment, and acid/alkali attack. Furthermore, the corrosion current density could be reduced by three orders of magnitude compared with that of bare steel.
Yao et al
The molecular structure models of asphalt binder, ethanol additive, and ethanol-based foamed asphalt were constructed through the Molecular Dynamics (MD) method. The standard ethanol-based foamed asphalt model was employed to describe the modifier with its different compositions, including 10%, 20%, and 30% ethanol. The simulation calculations were done for the ethanol-based foamed asphalt molecular models under the NPT and NVT ensembles. The density, glass transition temperature, and radial distribution function of ethanol-based foamed asphalt molecular models were obtained to verify the rationalization of asphalt models and analyze the variation of density parameters with temperature and ethanol content for ethanol-based foamed asphalt molecular models. The results show that the simulated densities of the asphalt binder and three ethanol-based foamed asphalt molecular models remained constant with the increase of simulation steps. The simulated density values of basic and 10%-ethanol-based foamed asphalt molecular models are close to 0.9 g/cm3. The simulated densities of 20%-ethanol-based and 30%-ethanol-based foamed asphalt molecular models were 0.8 g/cm3 and 0.75 g/cm3. Meanwhile, the simulated density values of both asphalt binder and all ethanol-based foamed asphalt decreased with the increase in temperature and ethanol additive dosage. The glass transition temperatures of basic asphalt binder, 10%-ethanol-based, 20%-ethanol-based, and 30%-ethanol-based foamed asphalt occurred in the range of 275-295K, 330-350K, 330-350K, and 320-340K, respectively. In contrast, the glass transition temperature of ethanol-based foamed asphalt increased with the increase of ethanol additive dosage, indicating that adding ethanol additive significantly improved the high-temperature resistance of matrix asphalt. In the radial distribution function diagrams of all samples, the first strong peak appeared at 0.85-1.3 Å, and the second strong peak appeared at 1.95-2.35 Å. Moreover, both peaks increased with the increase of ethanol additive dosage, suggesting that the contact between ethanol molecules and asphalt molecules was closer with the rise of ethanol additive dosage.
Wu et al
This research investigates the efficacy of bio-oil as a sustainable modifier for lignin-modified asphalt (LMA), aiming to enhance its performance characteristics. Utilizing Fourier transform infrared spectroscopy (FTIR) and scanning electron microscopy (SEM), the study analyzes the chemical and microstructural changes induced by bio-oil in LMA. Rheological properties were evaluated using Dynamic Shear Rheometry (DSR), revealing that the addition of 5-10% bio-oil to LMA significantly reduced stiffness and brittleness, improving ductility and fatigue resistance. For instance, LMAs with 10% bio-oil demonstrated a fatigue life at 2.5% strain comparable to unmodified asphalt. Additionally, bio-oil inclusion increased adhesive strength between asphalt and aggregates, enhancing moisture resistance. Low-temperature properties assessed by dynamic mechanical analysis (DMA) showed improved flexibility and thermal crack resistance with bio-oil addition. These findings underscore the potential of bio-oil in developing high-performance, sustainable asphalt binders, contributing to the advancement of eco-friendly road construction materials.
Chen et al
The dry sliding behavior of columnar Cu with vertical orientation (VO) and horizontal orientation (HO) coupling with 1045 steel was studied. The results show that when the sliding distance is 672 m, the friction coefficient of HO Cu is 0.21 lower than that of VO Cu, and the wear rate is reduced by 0.63·10-6 g·N-1m-1; when the sliding distance is 1344 m, the friction coefficient of HO Cu is 0.10 lower than that of VO Cu, and the wear rate is reduced by 0.31·10-6 g·N-1m-1. The Fe3O4 oxide was detected on the wear surface of HO Cu by Raman spectroscopy. And it plays a greater role in lubrication and protection of friction layer. On the worn surface of VO Cu, there is obvious softening caused by thermal activation or composition mixing. This softening will lead to a significant decrease in the strength of the friction layer, and the friction coefficient and wear loss increase negatively.
Wang et al
Shear-thickening fluids (STFs) are a new type of intelligent material with excellent performance whose viscosity increase sharply with the increase of shear rate or shear stress. However, the synthesis yield of dispersed phase particles is low, and the particle re-dispersion process is challenging for the industrial production of STFs. In this work, through structural design, a waterborne polyurethane (WPU) with typical shear-thickening properties was synthesized for the first time. This synthesis process is conducive to industrial production. The rheological properties of the synthesized WPU at different concentrations, temperatures, and pH were studied using a rheometer. The results showed that the WPU exhibited typical shear-thickening behavior. However, due to the special core-shell structure of the WPU particles, the shear rate has two transition responses to the shear-thickening behavior. With increasing concentration, the shear-thickening performance of the WPU is enhanced, and the critical shear rate is decreased. For the coexistence of Brownian motion and solvation, the rheological curve of the WPU exhibits a complex response to temperature increase; its shear-thickening behavior decreases with rising temperature, but the viscosity first decreases and then increases with temperature. Due to the presence of carboxyl groups on the surface of the WPU particles, its shear-thickening performance shows a strong response to pH. By appropriately adjusting the pH, the viscosity and particle size of the WPU can be increased through the ionization of carboxyl groups, thereby enhancing the shear-thickening behavior.