Formation Of Micropores Research Articles

Biobased Activated Carbon from Palm Biomass Enhancing with Acid Treatment as Supercapacitor Electrode Material

Current research on energy storage systems, batteries, and supercapacitor devices is aimed to enhance efficiency and improve environmental sustainability. Supercapacitors offer remarkable attributes such as high transient response and power density. Typically, supercapacitor electrode is made from highly porous carbon material, activated carbon. Commercial activated carbon could be produced from coal, peat, or coconut shell. This study focused on utilization of palm biomass, palm empty fruit bunch (EFB), as raw material to produce activated carbon electrode. The highly porous activated carbon from EFB was synthesized via a low-temperature hydrothermal process and chemical activation. The resulting EFB activated carbon demonstrates favorable characteristics in terms of elevated surface area and porosity. This research investigates the enhancement of activated carbon with acid treatment during hydrothermal process. Two types of acid, citric acid, and phosphoric acid, at different concentrations, were added to biomass. The acid-treated activated carbon from palm biomass was characterized for the specific surface area (BET), pore size distribution and pore volume using the N2 adsorption/desorption technique. The acid-treated activated carbon was fabricated into carbon electrodes and assembled in a symmetrical supercapacitor with 1M H2SO4 as an electrolyte. The supercapacitor performance of acid-treated activated carbon was tested in a symmetrical Swagelok cell to assess specific capacitance using cyclic voltammetry and galvanostatic charge-discharge methods. The acid-treated activated carbon has higher specific capacitance than the activated carbon without acid treatment. This superior performance is attributed to the reduced internal resistance as revealed by the Electrochemical Impedance Spectroscopy (EIS) result. This is possibly due to the formation of micropores in the range of 0.6−0.7 nm which is a suitable pore size for ion transportation in H2SO4 electrolytes. This research has shown that biobased activated carbon from palm oil biomass with acid treatment has a high potential to be used as supercapacitor electrode material. Keywords: Activated carbon, Palm biomass, Hydrothermal, Energy storage, Supercapacitor

Enhancing Tribological Performance of Self-Lubricating Composite via Hybrid 3D Printing and In Situ Spraying.

In this work, a self-lubricating composite was manufactured using a novel hybrid 3D printing/in situ spraying process that involved the printing of an acrylonitrile butadiene styrene (ABS) matrix using fused deposition modeling (FDM), along with the in situ spraying of alumina (Al2O3) and hexagonal boron nitride (hBN) reinforcements during 3D printing. The results revealed that the addition of the reinforcement induced an extensive formation of micropores throughout the ABS structure. Under tensile-loading conditions, the mechanical strength and cohesive interlayer bonding of the composites were diminished due to the presence of these micropores. However, under tribological conditions, the presence of the Al2O3 and hBN reinforcement improved the frictional resistance of ABS in extreme loading conditions. This improvement in frictional resistance was attributed to the ability of the Al2O3 reinforcement to support the external tribo-load and the shearing-like ability of hBN reinforcement during sliding. Collectively, this work provides novel insights into the possibility of designing tribologically robust ABS components through the addition of in situ-sprayed ceramic and solid-lubricant reinforcements.

Effect of temperature on the chemical activation of carbon nanospheres and their efficiency in supercapacitors

We report the synthesis of carbon spheres (CSs) by pyrolysis of soybean oil and their chemical activation employing acid baths at different temperatures. This allows to study the effect of these experimental parameters on the efficiency of these materials for their use as supercapacitor electrodes. The CSs were characterized by SEM, Raman, XRD, FT-IR, BET, and TEM to reveal the relationship between the electrochemical properties and the structure. Using nitric acid as the activating agent causes the formation of micropores and a high density of oxygenated functional groups in the CSs. In contrast, the mixture of sulfuric and nitric acids destroys the CSs, producing coalescence. The capacitance of the CSs was ~103 F g−1 at 5 mV s−1, and the contribution of electrical double-layer capacitance and pseudocapacitance was determined using cyclic voltammograms. Moreover, it is observed that after 1000 galvanostatic charge-discharge cycles at 2 A g−1, the CSs with the larger electrochemical capacitance increase their capacitive performance up to 38 %, maintaining the electrical double-layer capacitance contribution constant. Therefore, we show that controlling the density of oxygenated functional groups anchored through an increase in temperature during acid treatment and generating high surface areas are key parameters to obtain high capacitance.

Air-mediated phosphoric acid activation strategy for preparation of oxygenated functional groups rich activated carbon for capacitive deionization

Atmosphere during H3PO4 activation is vital to the texture structure and surface-interface properties of activated carbon (AC), but the researches are way out of sufficiency. In this work, it is found that the air in the H3PO4 activation process is not only conducive to the introduction of more-oxidized oxygenated functional groups on ACs, but also beneficial to the formation of micropores rather than mesopores. Besides, as the air content increases in H3PO4 activation, the ACs’ ash, phosphorous content and conductivity reduce, but their wettability, disorder degree and defect number increase. In addition, the potential of zero charge of the as-prepared ACs is positively correlated with the O-CO content, which show a pattern of first increasing and then decreasing with the increase of air content. Benefit from the improved hydrophilicity, electrolyte-affinity, additional adsorption sites for sodium ions, the optimal AC exhibits excellent salt adsorption capacity of 12.08 mg g−1 and good cycling stability at 1.0 V in single-pass capacitive deionization. This work not only establishes a novel and effective method for regulating the texture structure and surface properties of ACs, but also provides promising cathode candidates for capacitive deionization application.

Effects of corona discharge plasma pretreatment on the drying kinetics and quality attributes of lily (Lilium davidii var. unicolor) bulbs

The objective of this study was to examine the impact of corona discharge plasma (CDP) treatments of different durations (1, 3, 5, and 10 min) on the drying kinetics and quality attributes of lilies, including color, enzyme activities, total phenols content (TPC), and antioxidant activity. The microstructure of lilies under different CDP conditions were also investigated. As a result, all CDP treatments enhanced the drying rate relative to untreated lilies, and the shortest drying time of 7 h was obtained at CDP-3 minute samples. CDP treatment led to a higher retention in the TPC of dried lilies. Microstructural analysis revealed the formation of irregular micropores on the surface of the lilies after CDP treatment, which was closely associated with the accelerated drying rate and improved bioactive substances of the dried product. In conclusion, CDP has emerged as a novel and beneficial pretreatment technique that accelerates the drying process and enhances the nutritional qualities of dried lilies.

The effect of carbonization temperature on textural properties of sewage sludge-derived biochars as potential adsorbents

This article presents ways of recovering waste in the form of anaerobically digested and dried sewage sludge (average humidity approx. 6 wt%) by carbonization at various temperatures in the range of 400–900 °C. The resulting products, biochars, are investigated in terms of yield, surface properties and Raman spectra analysis. The sorption capacity of biochars differs depending on the carbonization temperature. The experimental amount of adsorbed CO2 slowly increases with the carbonization temperature from 0.212 mmol/g at 400 °C to the highest value of 0.415 mmol/g, which is achieved at 900 °C by slow carbonization at a rate of 10 °C/min. Additionally, there is a strong positive dependence of the adsorption capacity on the micropore volume. Higher carbonization temperatures support the powerful formation of micropores and improve their sorption capacity.

Removal of heavy metal ions from industrial (mining) wastewater using electromagnetically activated carbonaceous sorbent

Mining wastewater, characterized by elevated salt levels, necessitates effective treatment to prevent contamination of underground and surface water. Traditional methods for treating large volumes of mining wastewater with high total dissolved solids are expensive, and cost-effective alternatives are limited. In this study, we propose a solution to this challenge: the sorption of dissolved substances using a carbonaceous sorbent derived from waste, specifically rice husk biochar. To enhance the sorbent’s efficiency, we subjected it to electromagnetic activation, resulting in increased carbon content (from 43.3 to 78.5 % compared to the initial biochar), reduced impurities, and particle size reduction to the nanoscale (1–50 nm) with the formation of mesopores (mean diameter from the adsorption isotherm is 167 Å) and micropores (4.92 Å). This process contributes to improved compositional homogeneity. The effectiveness of the proposed sorbent was validated through the treatment of wastewater from Kirov Mine (Novoshakhtinsk, Rostov Region) under laboratory conditions. The removal rates for dissolved heavy metal ions (iron, zinc, manganese) were found to be 89, 84 and 26 %, respectively. A recommended two-stage sorption treatment involves: (1) static sorption using electromagnetically treated rice husk biochar at a concentration of 0.5 g/dm3; (2) subsequent reagent treatment of the suspension (SKiF-180 reagent, 1.0 mg/dm3), addition of potassium permanganate for manganese removal, settling for 30 min, and non-pressure filtration with a rice husk biochar filter.

Hierarchically porous electrospun carbon nanofiber for high-rate capacitive deionization electrodes

Capacitive deionization (CDI) is a promising technology that has gained interest for the desalination of brackish water. Hierarchically porous carbons are commonly used as electrodes for CDI due to their high surface areas and controlled pore size distributions that maximize ion adsorption capacity and rate. Electrospinning is an effective way of generating carbon nanofibers with high inter-fiber macroporosity that can be further modified to improve surface area, total pore volume, and pore size distribution. This work describes the use of sacrificial mesopore formers in tandem with a micropore etching technique to induce hierarchical porosity in electrospun fibers. Mesopores are formed via the dissolution of silica nanoparticles that are introduced into the fibers during the electrospinning step. After mesopore formation, micropores are etched into the resulting surface through KOH impregnation and thermal activation. This sequential technique creates a hierarchical network of pores from the inherent macroporosity of the fiber network, to the mesopores, and finally micropores to simultaneously maximize surface area and accessibility. Micropore formation is optimized to maximize specific surface area while maintaining physical integrity of the fibers. The combination of mesopores and micropores enables fast ion adsorption rates and capacity. Carbon fiber electrodes fabricated in this method achieve specific surface areas exceeding 1400 m2 g−1, with pore volumes exceeding 1.0 cc g−1. The pore size distributions are highly controlled, with 80 % of total pore volume coming from pores <20 nm in radius. In 500 ppm constant voltage CDI tests, these fiber electrodes obtain a salt adsorption capacity of over 14 mg g−1 at a salt adsorption rate of ∼4 mg g−1 min−1, showcasing the high capacity matched with high rate of these easily fabricated, inexpensive materials.

Creation of Porous, Perfusable Microtubular Networks for Improved Cell Viability in Volumetric Hydrogels.

The creation of large, volumetric tissue-engineered constructs has long been hindered due to the lack of effective vascularization strategies. Recently, 3D printing has emerged as a viable approach to creating vascular structures; however, its application is limited. Here, we present a simple and controllable technique to produce porous, free-standing, perfusable tubular networks from sacrificial templates of polyelectrolyte complex and coatings of salt-containing citrate-based elastomer poly(1,8-octanediol-co-citrate) (POC). As demonstrated, fully perfusable and interconnected POC tubular networks with channel diameters ranging from 100 to 400 μm were created. Incorporating NaCl particulates into the POC coating enabled the formation of micropores (∼19 μm in diameter) in the tubular wall upon particulate leaching to increase the cross-wall fluid transport. Casting and cross-linking gelatin methacrylate (GelMA) suspended with human osteoblasts over the free-standing porous POC tubular networks led to the fabrication of 3D cell-encapsulated constructs. Compared to the constructs without POC tubular networks, those with either solid or porous wall tubular networks exhibited a significant increase in cell viability and proliferation along with healthy cell morphology, particularly those with porous networks. Taken together, the sacrificial template-assisted approach is effective to fabricate tubular networks with controllable channel diameter and patency, which can be easily incorporated into cell-encapsulated hydrogels or used as tissue-engineering scaffolds to improve cell viability.

Fabrication of Particle-Stacking Microporous Metal Using Laser Powder Bed Fusion

Laser powder bed fusion can fabricate porous structures through lattices, but the preparation of micropores (&lt;50 μm) with a specific pore distribution remains a challenge. Microporous 316L was fabricated by controlling the melting and solidification behavior of the particles using laser energy. The laser energy density was not a determining factor for the porosity and micropore formation, except for the single-factor condition. The high-speed scanning mode required a higher laser power to disorder the pore distribution, whereas low-speed scanning with a low laser impact on the stacking particles formed organized pores. The hatch distance significantly affected the pore distribution and pore size. The pore distribution in the XY plane was organized and homogenous, with channeled pores mainly interconnected along the laser scanning tracks, whereas in the Z direction, it showed a relatively disordered distribution, mainly linked along the layered direction. The microporous 316L displayed a mean pore size and median pore size of 10–50 μm with a high-percentage size distribution in 1–10 μm, a controllable porosity of 17.06%–45.33% and a good yield strength of 79.44–318.42 MPa, superior to the lattice porous 316L with 250.00 MPa at similar porosity.

Construction of ultrathin and microporous polyesteramide nanofilms for efficient organic solvent nanofiltration (OSN) using diacyl chloride

The integration of high permeability and exceptional selectivity, thereby overcoming the conventional “trade-off” effect, remains a persistent challenge for the practical implementation of organic solvent nanofiltration (OSN) membranes. Herein, at the molecular level of design, we utilized the 5,5′-diamino-2,2′-biphenol (amino-BIPOL) and diacyl chloride as IP monomers to prepare OSN membranes with high perm-selectivity. The amino-BIPOL, a contorted biphenol molecule with four reactive sites, serves as a molecular-level unit to hinder efficient packing of polymer chains and induce the formation of interconnected micropores in the resulting polyesteramide layers. By employing diacyl chloride terephthaloyl dichloride (TPC) and isophthaloyl dichloride (IPC) as the oil-phase cross-linker, two kinds of TFC membranes were prepared. The resulting membranes both present smooth surface morphology, with ultrathin and high microporous selective layer allowing for efficient mass transfer. Specifically, the methanol permeance of amino-BIPOL/TPC and amino-BIPOL/IPC membrane reaches up to 15.1 and 15.6 LMH/bar, while maintaining a molecular weight cut-off (MWCO) value of 300 and 373 Da, respectively. Overall, this work illustrates the different oil-phase cross-linkers will result in diverse nanofilm microstructure and thus with distinct perm-selectivity properties, offering new insights for the design and modification of advanced OSN membranes.

Study on the preparation of porous polyethylene glycol terephthalate film and the influencing factors of etching rate

AbstractPorous polyethylene glycol terephthalate (PET) film is a kind of mesopore structure template with pore size ranging from nanometer to micrometer by chemical etching after irradiation of heavy ions. The etching rate is an important factor affecting the pore morphology and quality of the membrane. In this paper, four stacked PET film were irradiated with 140 MeV 32S ions at room temperature and vacuum. During chemical etching of irradiated samples, the path etching rate Vt was determined by conduction method, and the bulk etching rate Vb was determined by weighing method. The relationship between etching temperature, concentration, sensitization time, and etching rate was studied. The results show that the etching rate is exponentially correlated with the etching temperature, and increases linearly with the increase of the etching solution concentration. When the concentration of NaOH is 3 mol·L−1 and the etching temperature is 75°C, the formation of cylindrical micropores is the most favorable. The pore size of porous PET film can be adjusted, and the relationship between pore size and etching time is . This is of great significance for the preparation of nanowires with uniform size and stable properties.Highlights We have obtained the optimal conditions for obtaining cylindrical holes. The relationship between the diameter of holes and etching time were determined.

Structural and acoustical performances of oil palm trunk waste – Elastomeric thermoplastic polyurethane composite

In this report, naturally available materials have been utilized in the development of acoustic absorbers. This work presents the study of the effect of oil palm trunks dust (OPTD) loading to the mechanical and acoustical properties of elastomeric thermoplastic polyurethane (TPU). Four composite sheets of 3-mm thickness were prepared by varying the OPTD loadings with 10–40% wt into the polyurethane. Density, modulus elasticity, sound absorption coefficient and sound transmission loss of the samples were measured according to corresponding standards. The OPTD is found to reduce the density of the elastomeric polyurethane and at the same time, it increases the Young's modulus up to 215 MPa. The composite material can be applied as sound absorber panel installed in front of a rigid wall with an air gap. Increasing the air gap, thus lowering the air stiffness, shifts the absorption peak to a lower frequency. With OPTD loadings, the formation of micro-pores in the inner structure helps to improve the peak of sound absorption of the panel at the resonant frequency which can reach above 0.9. As the OPTD loading has effect on density, the effect on the sound transmission loss at the mass-controlled region is also apparent.

Investigation of electrical conductivity and electromagnetic wave absorption capabilities of water hyacinth biocarbon impregnated with Cu atom

This paper discusses the impregnation of Cu atoms at carbonization temperature of water hyacinth bio carbon composite. This composite is used as an absorber of electromagnetic waves. Because the inference of electromagnetic waves can cause damage to other electronic equipment. In addition, electromagnetic wave radiation can cause various human health problems. The purpose of the research is to obtain a material that is able to absorb electromagnetic waves and increase electrical conductivity, impregnation of Cu atoms at carbonization temperature of water hyacinth bio carbon composite. The composite material uses a composition ratio of water hyacinth powder and phenol-formaldehyde of 30:70. The carburization temperatures used were 600 °C, 800 °C, and 1000 °C with a heat increase rate of 7 °C/minute. This study used Scanning Electron Micrograph (SEM), X-Ray Diffraction (XRD), LCR Meter, and vector network analyzer. The results show that the impregnation of Cu atoms at carbonization temperature can increase the area of the nanostructure, thereby increasing the formation of micropores in the composite. The higher the carbonization temperature, the percentage of Cu and carbon compounds can increase, while the percentage of crystal structure decreases. Impregnation of Cu atoms further strengthens the composite's absorption of electromagnetic wave radiation. Impregnation of Cu atoms in water hyacinth bio carbon composites at carbonization temperature can increase the electrical conductivity of the composite. The results of this research have potential applications in the electronics industry, batteries, and electrical devices, and can be used to protect devices from electromagnetic interference, especially in telecommunications and the medical field

Influences of Different Acid Solutions on Pore Structures and Fractal Features of Coal

The effect of different acids on the pore structure and fractal characteristics of micropores and mesopores was determined with the help of low-temperature liquid nitrogen adsorption, X-ray diffraction, and the Frenkel–Halsey–Hill (FHH) model by using Yuwu coal as a sample and placing it in acidic environments, such as HF, HCl, HNO3, and CH3COOH. The results show that the acidization effects of HF and CH3COOH are separately dominated by the micropore and mesopore formation effects, while HCl and HNO3 mainly play their roles in expanding mesopores. After acidization, the surface fractal dimensions D1 and D1′ of micropores and mesopores in coal are always negatively correlated with the total specific surface area SBET, specific surface area Smic of micropores, and specific surface area Smes of mesopores. After being acidized by HF, D2 is negatively correlated with the total volume Vtot and the corresponding micropore volume Vmic, while acidization with HCl and HNO3 leads to the opposite result. After being acidized by CH3COOH, D2 has a negative correlation with Vtot and a positive correlation with Vmic. The structural fractal dimensions D2′ of mesopores in samples acidized by HF and CH3COOH are positively correlated with both the volume Vtot and mesopore volume Vmes, while it is the opposite for samples acidized by HNO3. D2′ of coal samples acidized by HCl is negatively correlated with Vtot while positively correlated with Vmes.

High temperature viscoelastic behaviour of sugarcane bagasse char and coal blends: Role of oxygen and porosity of char on fluidity reduction

This paper focuses on the introduction of sugarcane bagasse, an agricultural byproduct, as a renewable carbon-based additive to metallurgical coal to produce biocoke for the steel industry. Through subjecting pelletized sugarcane bagasse samples to various pyrolysis conditions, chars with varying properties were generated. With increasing final pyrolysis temperature (200, 400, 600, and 800 °C), a rise in carbon content and decline in oxygen, nitrogen and hydrogen levels in the chars were observed. The presence of an inert purge gas during pyrolysis prompted abundant micropore formation between 400 and 600 °C, yielding high specific surface area (SSA > 300 m2/g) chars at 600 °C and 800 °C. Conversely, chars produced in a fixed (unpurged) nitrogen environment exhibited minimal porosity and consequently low SSAs (<5m2/g). These various chars were then blended (at 10 % addition) with a medium-volatile bituminous coal to evaluate their impact on the viscoelastic properties of the coal. Chars pyrolyzed to lower final temperatures had the greatest detrimental effect on blend fluidity due to (1) their continued devolatilization which introduced void spaces in the blend creating pathways for the exhaust of coal volatiles, and (2) their elevated oxygen content, which scavenged essential mobile hydrogen needed to facilitate viscoelastic behaviour. Furthermore, chars with similar oxygen content but substantially different (by over two orders of magnitude) SSAs generated comparable coal-char blend viscosity profiles, indicating that the presence or absence of micropores in an additive does not significantly influence the viscoelastic behaviour of the coal. The reduction in blend fluidity for the addition of chars pyrolyzed to 800 °C was comparable to the modelled addition of inertinite macerals, implying that these high-temperature chars predominantly serve as inert solid additives. Comparison to a blend with 10 % mesoporous activated charcoal as the additive confirmed that it is mesopores that destroy fluidity, while micropores do not play a significant role. Mesopores were identified to adsorb/trap the relatively large tar-like compounds that are responsible for coal plasticity. Collectively, this research identifies three key factors contributing to fluidity reduction in coal-additive blends: void creation, oxygen content, and mesoporosity. These findings offer insights into optimizing biocoke production processes.

Selective pore regulation of activated carbon using trace carbonate-assisted catalytic activation: Revealing the effect of cation catalysis on pore topology

Activated carbon is an important adsorbent for the adsorption removal of water or gas pollutants due to its low cost, high efficiency, and large-scale production potential; however, currently commercial activated carbon prepared through physical or chemical activation commonly shows a single microporous characteristic, making it difficult to match different kinds of pollutants. Here, we propose a convenient and cost-effective pore regulation strategy by introducing a trace carbonate catalysis process into the activation reaction, in which we find that the types of cations (Na, K, Ca) in carbonate have a significant impact on the pore topology of coal-based activated carbon, further revealing the role of cation induced catalytic gasification in pore regulation. Therein, K and Ca enhance the formation of micropores and meso-/macropores respectively, while Na promotes the pore development across the entire size range resulting in a hierarchically porous structure with high specific surface area. Kinetic analysis, density functional theory calculations, and three-dimensional pore fractal network characterization reveal that the pore development is collectively determined by the gasification reaction rate and depth. Evaluated as adsorbents, the obtained NaAC sample by Na catalysis demonstrates excellent adsorption capacities for both small-molecule toluene (467 mg g−1) and large-molecule tetracycline (374 mg g−1). This work for the first time elucidates the cation-induced gasification effect and provides a simple and cost-effective method for regulating the pore topology of activated carbon with only trace catalyst dosage.

Spectrum of Nanopores, Micropores, and Associated Pore Networks and their Origins in Carbonate Strata

Nano- and micropores (defined as pores less than 10 μm in diameter) are common in carbonate reservoirs as either the sole pore type or in combination (dual pore networks) with matrix macropores and fracture pores. These very fine-scale pores form in limestones and dolostones and in associated organic matter (e.g., solid bitumen). Limestone nano- and micropores occur between crystals that are commonly less than 1 to 9 μm in size in limestone, but in dolostone the crystal size can be much larger. Limestone nano- and micropores commonly originate in three ways, although some inherited original nano- and micropores between mud components are preserved. First, in original lime-mud mixtures of aragonite, Mg–calcite, and calcite, the origin is both depositional and diagenetic as aragonite dissolves and reprecipitates because microrhombic calcite, Mg–calcite transforms to microrhombic calcite, and original calcite grains are generally unaffected. Second, in chalks, nano-and micropores are related to the original depositional fabric as interparticle pores between coccoliths and other pelagic allochems. Third, in sediment originally composed of Mg–calcite-rich allochems, nano-and micropores form by transformation of unstable Mg–calcite allochems to microrhombic calcite. In dolostones, nano-and micropores are associated with extensive dolomitization and the nearly complete occlusion of pores (overdolomitization), whereas another diagenetic origin in dolostones is differential dolomitization at the grain scale. Also, in some dolostones, nano- to micropores pores are inherited from precursor microporous limestone. A late process of nano- and micropore formation is subaerial weathering of both limestones and dolostones resulting in pulverulite. This form of micropores is commonly developed at unconformities as enhanced porosity zones. Organic-matter nano- and micropores in solid bitumen, common in thermally mature organic-rich argillaceous limestone, can also be present in coarser-grained carbonates in which solid-bitumen occurs within macropores. Only in organic-rich limestones do organic-matter pores have potential to form an effective pore system. Because nano- and micropores have multiple origins, their lateral and vertical distribution reflects or depends on their origin; therefore, one must not only describe nano- and micropores, but also define their origin. Recognition of nano- and micropores is important because they form tight carbonate reservoirs and have significant effects on permeability, porosity perseveration with burial, hydrocarbon saturation, hydrocarbon recovery, sweep efficiency, storage, and reserve estimations. Not recognizing nano- and micropore networks can lead to errors relative to the aforementioned measurements and as a result, economic evaluations may be invalid.

Effect of Hydrothermal Aging on the Tribological Performance of Nitrile Butadiene Rubber Seals.

High temperature and humidity affect the tribological performance of nitrile butadiene rubber (NBR) seals, which affects the precise positioning of cylinder systems. Therefore, it is crucial to study the effect of hydrothermal aging on the tribological performance of the NBR seals. In this study, the changes in the tribological performance of the NBR seals under hydrothermal aging conditions were investigated. The results show that the volatilization of additives and the increase in crosslink density of the NBR seals occurs in the hydrothermal aging environment, leading to the deterioration of their surface quality, elastic deformability, and tribological performance. The formation of surface micropores due to additive volatilization is the main factor in the degradation of tribological performance.

Flexible carbon nanofibers with multichannel and porous structure as freestanding anode for excellent sodium storage

Hard carbon is the most commonly used anode material for sodium-ion batteries (SIBs). However, it has the drawback of having inferior capacity at high rates due to low ion-diffusion kinetics. Rational design of hard carbon with a hierarchical pore structure and multichannel structure can address this issue. Herein, we introduced an electrospinning method for preparing flexible carbon nanofibers as a freestanding anode for SIBs. The pore structure can be modified by adjusting the amount of Pluronic F-127 (F127) added to the spinning solution. This strategy results in the formation of numerous micropores and mesopores, along with pore-derived defects, effectively increasing the number of sites available for sodium storage. The existence of multichannel facilitates the migration of sodium ions. PCNF-1 possesses an appropriate pore structure with the least amount of added pore-forming agent exhibits exceptional electrochemical performance. It delivers a reversible capacity of 286 mA h g−1 at a current density of 50 mA g−1 with an initial Coulombic efficiency (ICE) of 82 %. At 5 A g−1, it delivers a capacity of 211 mAh g−1. Furthermore, it demonstrates a high retention rate of 79 % at 1 A g−1 even after 1000 cycles. Notably, in full-cell tests, PCNF-1, when paired with a Na3V2(PO4)3 cathode, achieved a specific capacity of 253 mA h g−1 in the second cycle and maintained a retention rate of 51 % after 200 cycles at a current density of 1 A g−1.