Lithium-ion batteries (LIBs) have become a core technology for a wide range of energy-storage applications due to their high energy density and long cycle life. Within the electrode, the binder, which holds together the active materials, conductive additives, and current collector, plays a critical role in maintaining structural stability and ensuring stable electrochemical performance. However, conventional binders, such as poly (vinylidene fluoride) (PVDF) and water-based systems, are often unable to effectively accommodate the volume expansion or prevent interfacial degradation during repeated charge-discharge cycles. In this context, polyimide (PI) has emerged as a promising next-generation binder material owing to its excellent thermal and mechanical stability, as well as its tunable molecular structure enabled by diverse functional groups (e.g., -COOH, -NH2, -O-, -SO3H, -CF3). This review systematically examines PI binder synthesis strategies, structure-property relationships, and their applications in major electrode systems, including LFP, NCM, and Si-based anodes. In summary, polyimides are identified as high-performance multifunctional binders capable of stabilizing the electrode-electrolyte interface, enhancing ionic transport, and mitigating volume expansion. These structural design strategies provide important guidance for the development of next-generation high-energy-density LIBs.
Various wear particles generated on roads are dispersed by traffic, with repeated scattering caused by continuous vehicle movement. In contrast, road dust deposited on snowbanks remains immobilized, preventing further resuspension. In this study, road dust deposited on snow during winters and transferred from wet roads was collected to obtain samples transferred by single-step scattering. The tire wear particle (TWP) content was analyzed as a function of particle size. Rubber components were identified in samples smaller than 212 mu m : the styrene-butadiene rubber (SBR) content increased with decreasing particle size, whereas the natural rubber (NR) and butadiene rubber (BR) contents decreased. SBR was the predominant component in all samples, indicating that TWPs from passenger cars were more prevalent than those from buses or trucks. The TWP content ranged from 0.45% to 0.57%, which was lower than the values typically reported under dry road conditions.
This study investigates the chemical resistance of EPDM elastomer composites filled with silica of varying specific surface areas (SSA) when exposed to ammonia. The composites were immersed in 99.5% anhydrous liquid ammonia for 168 h, and changes in crosslinking density, volume, surface and fracture surface morphology, mechanical properties, and dynamic mechanical properties were evaluated before and after immersion. Exposure to ammonia resulted in an increase in crosslinking density, surface roughness, and glass transition temperature (Tg), along with decrease in volume and tan delta. The magnitude of these changes decreased with increasing silica SSA. Overall, EPDM composites containing higher-SSA silica exhibited improved stability in terms of crosslinking density, volume change, mechanical performance, surface characteristics, and dynamic mechanical behavior both before and after ammonia exposure. These findings demonstrate that silica SSA is a critical parameter in the design of EPDM-based seals and gaskets for use in 99.5% anhydrous liquid ammonia environments.
Rubber materials are extensively utilized in industrial applications because of their elasticity and ability to recover after deformation. However, vulcanized rubbers are prone to permanent deformation under thermal or mechanical stress due to variations in crosslink density. This study evaluated the recovery behavior of rubber-based composites blended with thermoplastic resins under circular deformation conditions. Six composite formulations were prepared by varying the plasticizer and vulcanization accelerator contents. The composites were processed via melt mixing and hot pressing, and rheometer measurements were performed to determine their crosslinking characteristics. Circular deformation tests were conducted at room temperature and at 80 degrees C to quantify their recovery performance after thermal aging. The 100% rubber vulcanizate exhibited the highest initial recovery (92.5%) and achieved full shape restoration within 8 h at room temperature. In contrast, thermoplastic-blended samples showed lower initial recoveries (78.7 similar to 86.2%) and delayed full recoveries up to 45 h. At 80 degrees C, all samples experienced residual strain, with the rubber-only sample recovering up to 93.7%, whereas blended samples ranged between 71.2% and 78.0% recovery. Notably, despite the reduced recovery performance, the thermoplastic blends exhibited enhanced mechanical strength and abrasion resistance. These results highlight the trade-off between thermal recovery and mechanical reinforcement when thermoplastics are incorporated. The insights gained from this study can be used to optimize the fabrication of thermoplastic-rubber composites for applications requiring tailored elastic and thermal-aging performance.
With t he global rise in plastic use, concerns over microplastics generated through weathering processes are intensifying. While many studies have examined the occurrence and impacts of microplastics, relatively few have systematically explored the weathering behavior of different plastic types. This review focuses on the mechanisms of weathering and associated property changes in representative plastics, polyethylene (PE), polypropylene (PP), and polyethylene terephthalate (PET), with an emphasis on Raman and infrared (IR) spectroscopy. These nondestructive techniques enable the identification of chemical changes such as oxidation, carbonyl formation, and surface degradation. However, no standardized protocol currently exists for plastic-specific weathering assessments. Additionally, significant differences persist between artificially aged microplastics and those found in the environment, which are often associated with biofilms, organic matter, and pollutants. These discrepancies complicate the interpretation of environmental behavior and toxicity. Therefore, there is an urgent need for experimental models and analytical methods that better reflect real-world conditions and facilitate accurate cross-comparisons among plastic types. This review aims to support such efforts by summarizing current knowledge and identifying key gaps in microplastic weathering research.
This study presents the design and performance evaluation of a hollow-type passive shock isolator for mitigating high-mass impact. The properties of the hyperelastic material were characterized through static tests and incorporated into a finite element model for design optimization. The isolator reduces shock transmission in both vertical and horizontal directions, ensuring the structural safety of mounted equipment in modern weapon systems. Rubber, a typical hyperelastic material, exhibits strong elasticity but requires careful design to withstand repeated loads and high stresses without degradation. A prototype isolator was fabricated, and its shock absorption performance was validated by impact load testing. The results confirm that the proposed design effectively attenuates impact forces, demonstrating a strong potential for practical applications.
Three carboxylic acids with varying chain lengths, succinic acid (SUA), adipic acid (ADA), and sebacic acid (SA), were used to modify nanosized boron nitride (BN) to enhance the mechanical properties and thermal conductivity of an epoxy/benzoxazine resin. Surface modification significantly reduced the viscosity of the epoxy/benzoxazine/BN adhesives, primarily due to improved compatibility between the resin and BN fillers. The adhesion strength to silver (Ag), copper (Cu), and gold (Au) lead frames increased at all tested temperatures following surface treatment. Thermal conductivity remained largely unaffected by the type of carboxylic acid, maintaing a consistent value in the range of 0.37-0.39 W/mK at 30 wt% BN loading.
This study focuses on developing low-dielectric-loss silica-based polydimethylsiloxane (PDMS) composite films for application in 5G printed circuit boards. With the increasing demand for high-frequency, high-speed communication systems such as 5G and beyond, materials with superior dielectric properties are essential for minimizing signal degradation. In this study, we fabricated composite films using PDMS and varying weight percentages (10-60 wt%) of silica fillers (MS5000 and MS1000). The dielectric properties, mechanical strengths, and thermal stabilities of the films were investigated. The results reveal that the dielectric constant of the films increased with increasing filler content, while the dielectric loss decreased. Specifically, films containing 10 wt.% of MS5000 and MS1000 exhibited dielectric constants of 2.9135 and 2.8760, respectively, whereas films containing 60 wt.% of the same fillers demonstrated dielectric losses of 0.0154 and 0.0149, respectively. Additionally, the thermal stability of the films improved with increasing silica content, and mechanical testing showed that while the elongation decreased,Young's modulus increased, highlighting the tradeoff between flexibility and stiffness. These findings indicate that by optimizing the filler content, PDMS-silica composite films could be promising for high-frequency applications in 5G communication systems.
A nickel zeolitic imidazolate framework/carbon nanotube (Ni-ZIF/CNT) nanocomposite was synthesized by reacting nickel(II) nitrate hexahydrate with 2-methylimidazole and carbon nanotube. Its morphology and structure were characterized using scanning electron microscopy, powder X-ray diffraction, Fourier transform infrared spectroscopy, and Raman spectroscopy. The catalytic activity of the nanocomposite for the reduction of nitroaromatic compounds, including 4-nitroaniline and 4-nitrophenetole, was monitored using an ultraviolet-visible spectrophotometer. The kinetics of the catalytic reduction of nitroaromatic compounds followed a pseudo-first-order reaction rate law. The Ni-ZIF/CNT nanocomposite prepared with 15 wt.% CNT exhibited the highest catalytic performance in the reduction of nitroaromatic compounds. The rate constants (k) for the reduction of 4-nitroaniline and 4-nitrophenetole by the Ni-ZIF/CNT nanocomposite containing 15 wt.% CNTs were 0.1930 and 0.1106, respectively.
This study provides an overview of the design and implementation of side steps for multipurpose vehicles (MPVs), sports utility vehicles (SUV), and pickup trucks, emphasizing the need for customization to meet diverse functional requirements. Side steps are essential for improving vehicle accessibility, particularly in large vehicles such as SUVs, where step-in heights pose challenges for passengers, especially elderly individuals and children. The design of side steps must account for vehicle height, user demographics, and aesthetic integration with the vehicle design. Customization is often necessary to satisfy specific requirements, such as enhanced durability for off-road applications or a refined appearance for luxury models. This study highlights the advantages of side steps, including improved safety, ease of access, and potential aesthetic enhancement. In addition, disadvantages such as increased weight, which can reduce fuel efficiency, and the complexity associated with retractable designs, are discussed. Factors influencing implementation, including material selection, integration with existing vehicle systems, and durability under harsh environmental conditions, are also explored. Finally, potential solutions and future research directions, such as employing lightweight materials and advanced manufacturing techniques, are suggested to overcome these challenges and improve the performance and reliability of side steps in SUVs and MPVs.
The kneading effect was studied according to the screw profile of polypropylene (PP)/low-density polyethylene (LDPE) blends. To increase the efficiency of the twin-screw extruder process, the optimal process conditions were set using an extrusion simulation program. After measuring the thermal and rheological properties of the two matrices and entering the material information, the extrusion process was simulated to determine the conditions that maximized the kneading effect. In addition, a screw profile that increases the kneading effect was designed by analyzing the specific mechanical energy, residence time distribution, torque, and temperature change results of the simulation program. After extrusion, the kneading effect of the PP/LDPE blend was analyzed using scanning electron microscopy (SEM), differential scanning calorimetry, and rotational rheometry. The SEM images indicated an increase in the kneading effect between the two matrices, and the shear effect of the material owing to the differences in the screw profiles was determined from the rheological property results. The actual measurements tended to be consistent with the simulation results, and the study of the screw profile design and optimal process conditions using the simulation program effectively improved the kneading effect without material degradation.
This study investigates the effects of curing agents on the damping and mechanical properties of composites made from ethylene-propylene-diene monomer (EPDM) and isobutylene-isoprene rubber (IIR). In the rubber industry, EPDM is favored due to its excellent resistance to aging, ozone, UV radiation, and various chemicals. However, it has certain limitations, including high gas permeability and poor shock absorption. To address these shortcomings, EPDM is blended with IIR, which offers superior shock absorption and heat resistance in enhancing the overall properties of the composites. The study further examines the role of carbon black as a reinforcing filler for improving the mechanical and damping properties of the blends. Two curing agents, sulfur and peroxide, are used to cross-link the rubber composites, and their effects on the mechanical performance, crosslink density, thermal aging resistance, and damping characteristics are evaluated. The findings reveal that peroxide curing results in more stable crosslinks and better thermal stability than sulfur curing. By contrast, sulfurcured blends exhibit a higher tensile strength. An optimal balance between elasticity and anti-vibration properties is achieved with peroxide curing at a concentration of 0.5 phr. These findings can contribute to the development of rubber composites with enhanced mechanical and thermal properties for various industrial applications.
Lithium-ion batteries (LIBs) are essential for modern energy storage However, they face significant manufacturing issues related to toxic solvents, high-energy consumption, and thick electrode fabrication. Dry-electrode manufacturing provides a solvent-free alternative that reduces the environmental impact while improving productivity and facilitating the uniform production of thick-electrode through polytetrafluoroethylene (PTFE) fibrillation. This review evaluates key dryfabrication methods, including electrostatic-spray deposition, pressing-based fabrication, extrusion-based processing, and rollmill processing, and demonstrates how PTFE fibrillation enhances both mechanical integrity and electrochemical performance. Despite ongoing challenges, such as regulatory concerns related to PTFE decomposition under lithiation, and the need for specialized equipment, the field is progressing through the development of novel binders and process optimization. In addition, the compatibility of dry-manufactured electrodes with emerging technologies, particularly all-solid-state batteries, underscores the transformative potential of this approach. As research continues, dry-electrode manufacturing is positioned to produce more sustainable and high-performance LIBs at scale.
In this study, the effects of crosslinker concentration on the physical and mechanical properties of polyurethane (PU), an underwater sound-absorbing material, were investigated. Trimethylolpropane (TMP) was employed as a crosslinker, and its concentration was adjusted to examine its impact on the material properties. Dynamic mechanical analysis, differential scanning calorimetry, Fourier-transform infrared spectroscopy, and tensile testing were performed to analyze the material characteristics. As the TMP content increased from 25% to 100%, the elastic modulus increased by approximately 103.8%, corresponding to a nearly 300% change in TMP concentration. The loss factor, which is closely related to sound-absorption performance, increased by up to 27.19% with increasing TMP content. Additionally, the loss factor was found to increase by up to 13.68% as the temperature decreased from 30 to 10 degrees C. These findings indicate that the mechanical properties and loss factor of PU improved at lower temperatures and higher TMP concentrations, thereby providing insights into the effective design of sound-absorbing materials.
An acrylic polymer matrix with a high-temperature resistance was developed for rubber materials using a redoxinitiated emulsion polymerization process, which is an appropriate method for large-scale low-temperature production. In this study, highly polar acrylonitrile monomers were incorporated into the matrix design to enhance the processability of rubber manufacturing and improve its mechanical properties. The incorporation of strong polar functionalities into the polyacrylic rubber matrix is expected to enhance heat, oil, and chemical resistance and improve gas barrier properties. These expected characteristics demonstrate the significance of this research in providing foundational molecular design techniques for advanced applications of gaskets and sealing products, particularly in extreme environments.
In this study, we observed the effect of thermal degradation on the low-temperature sealing capability. A large- sized CR O-ring of 90.0 mm inner diameter and 7.0 mm cross-sectional diameter was used. In FT-IR spectroscopy, the aged CR O-ring, CR-10, showed a carboxyl group upon oxidation. Through oxidation, the sealing force of the aged CR O-rings decreased with an increase in the degree of degradation. As the degree of degradation increased, the 10% compressive modulus had higher values at each relative position. Oxidation was caused by oxygen diffusion to the CR interface. As the degree of degradation increased, glass transition temperature (Tg) was increased, and tan delta was decreased. CR-10 showed -44.0 degrees C of Tg and 0.89 of tan delta. With an increase in the degree of degradation, the mobility of the CR decreased and showed a slow recovery rate at low temperatures. All specimens showed lower temperature retraction 10 (TR10) than Tg with 2.0-2.5 degrees C difference. The gas leakage temperature increased with the degree of degradation. This coincided with Tg and TR10 tendency. Under Tg and TR10, CR could still exhibit viscoelastic properties and could be used as a seal. At the gas leakage temperature, the CR changed to a glassy state, and leakage occurred.
A novel aromatic polyimide containing the 4-tert-butyl group was prepared from 4-tert-butyl-1,2-phenylene bis(4-aminobenzoate) and 4,4'-(hexafluoroisopropylidene)diphthalic anhydride (6FDA). 4-tert-Butyl-1,2-phenylene bis(4aminobenzoate) was synthesized from 4-tert-butyl catechol and 4-nitrobenzoyl chloride. The poly(amic acid) was transformed into a polyimide via chemical imidization. The polyimide was soluble in N-methyl-2-pyrrolidone (NMP) and could be cast into a flexible and transparent film. The thermal stability of the polyimide was decreased slightly due to the pendant tertbutyl group.
Due to its unique physical, mechanical, and chemical properties, hydroxyl-terminated polybutadiene (HTPB) is an essential telechelic polymer that is used and applicable in areas ranging from automotive to aerospace and coatings industries. It is a key precursor in polyurethane chemistry and is celebrated for its versatility and ability to undergo various post-polymerization modifications to meet specific industrial needs. This review focuses on the sophisticated methodologies employed to enhance the stability and functionality of HTPB through targeted chemical modifications. Representative techniques include hydrogenation, which suppresses the oxidation susceptibility of polymers by saturating weak double bonds, and epoxidation, which introduces epoxy groups that increase the reactivity and compatibility with polar additives. These modifications not only preserve the inherent attributes of HTPB, they also amplify their utility across a spectrum of applications, from aerospace to automotive industries, where enhanced material performance is critical. This study outlines the challenges in modifying HTPB, discusses the chemical strategies employed, and showcases the improved performance characteristics of the resulting polymers, thus providing a comprehensive overview of the current advancements and future potential of HTPB utilization.
Indoor parking garages have concrete-paved inclined ramps, contributing to high tire friction and increased slip angles. Therefore, the abrasion behavior of tire treads on an indoor parking garage ramp differs from those on common asphalt-paved roads, leading to variations in the generated TRWPs. The TRWP densities ranged from low (< 1.1 g cm-3) to high (> 1.8 g cm-3), and the degree of mineral particles adhering to the surface of tire wire particles increased with density. The densities and aspect ratios of the TRWPs generated in the parking garage varied depending on the ascent and descent ramps and the slip angles of tires. The TRWPs generated in the parking garage were distributed at a lower density than those produced on asphalt-paved roads and had lower aspect ratios. TRWPs generated from tires at large slip angles mostly exhibited densities below 1.1 g cm(-3) on the ascent and descent ramps in the parking garage. Such low-density TRWPs can be easily resuspended by traffic in the air and may remain suspended in aquatic environments for prolonged periods upon entering rivers and seas.
Nanorod graphitic carbon nitride (g-C 3 N 4 ) was synthesized by reacting melamine (C 3 H 6 N 6 ) with trithiocyanuric acid (C 3 H 3 N 3 S 3 ) in distilled water for 10 h at room temperature. The resulting mixture was calcined at 550 degrees C for 2 h in an electric furnace under an air atmosphere. Nanorod g-C 3 N 4 /Ag 3 PO 4 composites were prepared by adding nanorod graphitic carbon nitride (g-C 3 N 4 ) powder, silver nitrate (AgNO 3 ), ammonia (NH 3 center dot H 2 O, 25.0-30.0%), and sodium hydrogen phosphate (Na 2 HPO 4 ) to distilled water. The samples were characterized via X-ray diffraction, scanning electron microscopy, and Fourier-transform infrared spectroscopy. The photocatalytic activities of the nanorod g-C 3 N 4 /Ag 3 PO 4 composites were demonstrated via the degradation of organic dyes, such as methylene blue and methyl orange, under blue light-emitting diode irradiation and evaluated using UV-vis spectrophotometry.
