Fiber Felt Research Articles

Activated Carbon Fiber Felt Composites for the Direct Air Capture of Carbon Dioxide.

Negative emissions technologies to mitigate climate change require innovative solutions for the direct air capture (DAC) of CO2 from the atmosphere. K2CO3 readily reacts with CO2 to form KHCO3; however, bulk K2CO3 suffers from very slow sorption kinetics. By incorporating K2CO3 into activated carbon (AC) fiber felts, the sorption kinetics were significantly improved by increasing the surface area of K2CO3 in contact with air. The AC-K2CO3 fiber composite felts are flexible, cheap, easy to manufacture, chemically stable, and show excellent DAC capacity and (de)sorption rates, with stable performance up to ten cycles. Cyclic testing was demonstrated with 4 h sorption and 0.5 h desorption intervals. The best composite felts collected an average of 478 μmol of CO2 per gram of composite during 4 h of exposure to ambient air (19 % relative humidity) that had a CO2 concentration of 400-450 ppm after regeneration at 125 °C in an air furnace. An increase in the dew point temperature from 0 to 12 °C decreased sorption performance of the composite felts by 40 %.

A methodology for selection of solid desiccants in energy recovery ventilators

Controlling indoor humidity levels is essential for maintaining acceptable indoor air quality in buildings. The use of energy recovery ventilators (ERVs) is an energy-efficient way to regulate indoor air humidity. Fixed-bed regenerators and rotary wheels are widely used ERVs because of their high sensible and latent effectiveness. These ERVs are made of desiccant-coated substrates, which enable them to transfer moisture between the supply and exhaust air streams. However, the moisture transfer ability of ERVs depends on the physiochemical and sorption properties of desiccants. Extensive, full-scale experiments are required to determine the best desiccant material for these systems. This paper presents a simplified method of selecting suitable desiccant materials for ERVs. The methodology involves important characterization methods, literature correlations for performance prediction, and cost-effective testing methods prior to full-scale testing, and full-scale test methods are discussed in detail. Furthermore, the performance of a few newly derived materials is evaluated and compared with that of conventional desiccants such as silica gel and molecular sieves. The highest latent effectiveness was obtained for composite of super absorbent polymer (SAP) with potassium formate (SAP-HCO2K-50 %), all-polymer porous solid desiccant (APPSD) and metal organic framework (MOF)–MIL–101 (Cr), followed by activated carbon fibre felt (ACF) Silica sol-LiCl30, SAP, silica gel, MOF–303, and molecular sieve. Researchers and manufacturers would benefit from the proposed methodology and presented data in developing new desiccant materials for ERV applications.

Fabrication of Micro/Nanostructured Copper Fibers by Vibration Cutting for Felt-Based Freshwater Purification

Freshwater purification from wasted water and seawater is crucial in addressing the global problem of water scarcity. Porous fiber felt with a micro/nanostructure emerges as an efficient approach for water purification; however, its production usually relies on chemical postprocessing to create micro/nano structures on the fiber surface, which might pollute the environment. This study proposed an ecofriendly method to produce micro/nanostructured copper fiber felt without chemical treatment. First, a new transverse-feeding vibration cutting is proposed to fabricate micro/nanostructured fibers with controllable structure characteristics. Through the sintering of the structured fibers without postprocessing, the fiber felt can be produced in an ecofriendly way and exhibit special wettability and excellent photothermal properties. Felt-based freshwater purification, including oil–water separation and solar-driven seawater desalination, can be realized effectively. Results show an oil–water separation efficiency of > 90% and a high evaporation rate of water of > 1.08 kg m−2 h−1 at 73 mW cm−2 are achieved, demonstrating the application prospect of the produced fiber felt.

Design and performance study of a kilowatt-class PEMFC stack with metal fiber felts as flow fields

The study presents a comprehensive design and evaluation of a kilowatt-class proton exchange membrane fuel cell (PEMFC) stack, wherein stainless steel fiber felts are innovatively utilized as flow fields. The impacts of critical operating parameters, namely operating temperature, pressure, and reactant gas relative humidity, on the performance of the 22-cell stack with an active area of 83 cm2 were thoroughly investigated. An analysis of the voltage consistency among individual cells was conducted across varying operating conditions and output currents. The total power output of the PEMFC stack reaches 1183W under the fundamental operating conditions, where each cell achieves an average voltage of 0.6V. As the operating temperature and pressure are incremented, the stack’s output power exhibits a noticeable increase. The optimal range for the reactant gas relative humidity is found to be 60% to 80%. As the output current increases, the voltages of individual cells gradually decrease and the voltage consistencies tend to deteriorate. The optimal operating conditions for achieving the best voltage consistency vary with current density.

Multi-scale modeling: Finite element analysis of the thermophysical properties of carbon/carbon composites considering manufacturing defects and porosity at high temperature

Carbon/carbon (C/C) composites have strict requirements for their thermal properties in extreme environments, especially at high temperature, where their properties are crucial for long-term life. The structure of C/C composites is exceptionally complex and exhibits multi-scale characteristics, and their thermophysical properties are closely related to temperature. Therefore, exploring their thermal response and heat transfer mechanisms through experimental method is relatively costly. This paper constructs a multi-scale finite element model to investigate the influence of structure and manufacturing defects on performance, and analyzes the thermophysical properties of the composites at High-temperature. By constructing a micro-representative volume element (Micro-RVE) that includes fibers, matrix, and pores, and using a steady-state heat transfer analysis method, the influence of material phase distribution on performance is studied. At the same time, a Meso-RVE reflecting the layering form, needle punching effect and manufacturing defects is established, and the transient heat transfer analysis method is used to investigate the influence of the structural form on performance. Finite element analysis shows that, the simulation values of the three C/C composites of unidirectional fiber bundles, short-chopped fiber felts, and needle punched C/C composites show good consistency with the experimental results in the published literature. This paper uses numerical methods to calculate the thermophysical properties of C/C composites from room temperature to 900°C and explores their variation with temperature. The constructed multi-scale model provides an accurate and effective method for predicting the thermophysical properties of C/C composites and also provides new perspectives and insights for thermal-mechanical coupling analysis and structural design.

Effect of Fiber Characteristics on the Structure and Properties of Quartz Fiber Felt Reinforced Silica-Polybenzoxazine Aerogel Composites.

Fiber-reinforced aerogel composites are widely used for thermal protection. The properties of the fibers play a critical role in determining the structure and properties of the final aerogel composite. However, the effects of the fiber's characteristics on the structure and properties of the aerogel composite have rarely been studied. Herein, we prepared quartz fiber felt-reinforced silica-polybenzoxazine aerogel composite (QF/PBSAs) with different fiber diameters using a simple copolymerization process with the ambient pressure drying method. The reasons for the effects of fiber diameter on the structure and properties of the aerogel composites were investigated. The results showed that the pore structure of the aerogel composites was affected by the fiber diameter, which led to significant changes in the mechanical behavior and thermal insulation performance. At room temperature, pore structure and density were found to be the main factors influencing the thermal conductivity of the composites. At elevated temperatures, the radiative thermal conductivity (λr) plays a dominant role, and reducing the fiber diameter suppressed λr, thus decreasing the thermal conductivity. When the QF/PBSAs were exposed to a 1200 °C butane flame, the PBS aerogel was pyrolyzed, and the pyrolysis gas carried away a large amount of heat and formed a thermal barrier in the interfacial layer, at which time λr and the pyrolysis of the PBS aerogel jointly determined the backside temperature of the composites. The results of this study can provide valuable guidance for the application of polybenzoxazine aerogel composites in the field of thermal protection.

Efficient Solution Blow Spinning of PAN-CNTs Nanofiber-Based Pressure Sensors with Sandwich Structures.

High-performance sensors play a crucial role in smart wearable technology and human-machine interaction. However, traditional metal- and silicon-based sensors face drawbacks, including limited flexibility, high cost, degradation issues, and insufficient sensitivity. Conductive composite fibers were produced using the spinning solution of PAN and PVB mixed with CNTs and spun at a flow rate of 20 mL·h-1. PAN-CNTs fiber felt formed a sandwich structure by impregnating CNTs aqueous solution, mechanical pressing, and coating graphene. A cost-effective PAN-CNTs nanofiber-based pressure sensor (PCPS) was developed, demonstrating excellent flexibility, conductivity, sensitivity, mechanical properties, and biocompatibility. Nanofiber-based pressure sensors exhibited high sensitivity, with an approximately 75% relative resistance change under a 1 N pressure load. They can withstand 360° bending and have a rapid response time of about 160 ms. PCPS holds significant potential for flexible electronics, smart wearables, and micropressure detection.

Anisotropic Thermal Conductivity of Epoxy Laminate Composites Constructed with Three-Dimensional Carbon Fiber Felt

Anisotropic Thermal Conductivity of Epoxy Laminate Composites Constructed with Three-Dimensional Carbon Fiber Felt

Highly hygroscopic needle-punched carbon fiber felt with high evaporative cooling efficiency and fire resistance for safe operation of ultrahigh-rate lithium-ion batteries

The effective thermal management of lithium-ion batteries is the key to ensuring their fast charging-discharging, safe and efficient operation. Herein, inspired by transpiration-driven water transport in plants, we report a highly hygroscopic needle-punched carbon fiber felt (HS/CFF) with high evaporative cooling efficiency and fire resistance for the safe operation of lithium-ion batteries working at ultrahigh-rate conditions. The three-dimensional fiber skeleton structure constructed by needle punching in the carbon fiber felt enables effective water transport and storage in HS/CFF, without any water leakage. At an ultra-high discharge rate of 10 C, HS/CFF can reduce the maximum temperature of commercial lithium-ion batteries by 18 °C, and can keep the battery temperature below 60 °C. During 500 cycles of charge-discharge, HS/CFF maintains stable evaporative heat dissipation performance, which helps to improve the safety of lithium-ion batteries and extend their service life. Moreover, HS/CFF remains non-combustible even under exposure to a flame (600-700 °C) for 10 min, and the HS/CFF can be reused after the burning test, with the original excellent heat dissipation effect unchanged. This flexible, fire-resistant cooling material offers a promising avenue for low-energy intelligent thermal management of lithium-ion batteries and other heat-generating electronic devices.

Carbon fiber felt scaffold from Brazilian textile PANfiber for regeneration of critical size bone defects in rats: A histomorphometric and microCT study.

The objective of the present study was to evaluate the carbon fiber obtained from textile PAN fiber, in its different forms, as a potential scaffolds synthetic bone. Thirty-four adult rats were used (Rattus norvegicus, albinus variation), two critical sized bone defects were made that were 5 mm in diameter. Twenty-four animals were randomly divided into four groups: control (C)-bone defect + blood clot, non-activated carbon fiber felt (NACFF)-bone defect + NACFF, activated carbon fiber felt (ACFF)-bone defect + ACFF, and silver activated carbon fiber felt (Ag-ACFF)-bone defect + Ag-ACFF, and was observed by 15 and 60 days for histomorphometric, three-dimensional computerized microtomography (microCT) and mineral apposition analysis. On histomorphometric and microCT analyses, NACFF were associated with higher proportion of neoformed bone and maintenance of bone structure. On fluorochrome bone label, there was no differences between the groups. NACFF has shown to be a promising synthetic material as a scaffold for bone regeneration.

Development of Bromine Adsorbing Carbon Felt Electrode by Coating of Nitrogen-Doped Mesoporous Carbon Layer for Highly Stable Flowless Zinc-Bromine Battery

Renewable energy is well known for the extreme volatility of power production, and secondary battery-based energy storage systems (BESS) are the key to the novel and safe energy industry to expand the supply of renewable energy. Currently, lithium-ion battery-based ESS is commonly used, but the frequent ignition accidents from these ESSs rather become an obstacle to the growth of the renewable energy field. Among the redox batteries, the flowless zinc-bromine battery (FLZBB) is studied as the alternative since it uses a non-flammable and cost-effective aqueous Zn- Br2 electrolyte. However, its main challenges are that bromine (Br2) and polybromide anions (), formed at the positive electrode during the charging process, cross over to the negative electrode due to the difference in chemical potential between the electrodes. The diffused Br2 oxidizes the zinc metal, electrodeposited on the negative electrode, and causes a self-discharge reaction that consumes the charging active material and Br2 the battery performance and life. Herein, we present a nitrogen-doped mesoporous carbon coated on the pristine graphite felt fibers (NMC/GF). By uniformly forming a nitrogen-doped porous carbon material on the GF fibers through the evaporation-induced self-assembly (EISA) method, it is a simple and cost-effective method to develop the structural and properties of the GF positive electrode to increase the ability of adsorption and storing the active materials, Br2 and polybromide anions (,, and ) generated during the charging process. In addition, it also improved the bromine redox reaction kinetics by having a strong affinity with the aqueous Zn-Br2 electrolyte. This facilitates long-term charge/discharge cycles, enabling high performance and improved durability for Coulombic efficiency over 95% for 5000 cycles in the FLZBB single-cell platform at a current density of 20 mA cm-2 and a high-rate areal capacity of 2 mAh cm-2.

Experimental investigation of the effects of altitude on the performance of a non-sprayed porous burner

A self-sustained burner was built for diesel oil without an atomizer using metal fiber felt as an evaporator. The effects of firing rate, excess air coefficient, and altitude on the temperature distribution, NOx emission, and CO emission were studied. The results indicated that fuel evaporation and combustion inside the burner are significantly influenced by the altitude. The overall temperature distribution inside the burner first decreased and then increased with the increase in altitude. The main reasons for the formation of NOx are the local high temperature during start-up and the high temperature after flame stabilization. The NOx emission initially decreased and then increased with the increase in altitude. The NOx emission is the lowest at an altitude of 1700 m and reaches its maximum value at an altitude of 4780 m. The main cause of CO generation is incomplete combustion during the start-up process. The CO emission decreased with the increase in the excess air coefficient at the same altitude. Less CO is produced with the increase in altitude at the same firing rate and excess air coefficient.

Flexible Hybrid Supercapacitor Achieving 2.2V with NiCo2S4/Polyaniline/MnO2 and N, S-Co-Doped Carbon Nanofibers for Ultra-High Energy Density.

Flexible all-solid-state asymmetric supercapacitors (FAASC) represent a highly promising power sources for wearable electronics. However, their energy density is relatively less as compared to the conventional batteries. Herein, a novel ultra-high energy density FAASC is developed using nickel-cobalt sulfide (NiCo2S4)/polyaniline (PANI)/manganese dioxide (MnO2) ternary composite on carbon fiber felt (CF) as positive and N, S-co-doped carbon nanofibers (CNF)/CF as negative electrode, respectively. Initially, porous δ-MnO2 nanoworm-like network is decorated on CF using potentiodynamic method. Subsequently, interconnected PANI nanostructures is grown on the MnO2 via a facile in situ chemical polymerization, followed by the electrodeposition of highly porous NiCo2S4 nanowalls. Benefiting from 3D porous structure of conductive CF and redox active properties of NiCo2S4, PANI and MnO2, FAASC achieved a superior energy storage capacity. Later, high-performance N, S-co-doped CNF/CF negative electrode is synthesized using electropolymerization of PANI nanofibers on CF, followed by the carbonization process. The assembled FAASC exhibits a wide voltage window of 2.2V and remarkable specific capacitance of 143 F g-1 at a current density of 1 A g-1. The cell further delivers a superb energy density of 71.6Wh kg-1 at a power density of 492.7W kg-1, supreme cycle life and remarkable electrochemical stability under mechanical bending.

Roll-to-roll joule-heating to construct ferromagnetic carbon fiber felt for superior electromagnetic interference shielding

The effective safeguard from electromagnetic radiation damage via electromagnetic interference shielding (EMI) materials is crucial for diverse applications, especially in modern aerospace, medical, and human body protection endeavors. Despite great efforts have been made to surmount challenges encompassing scalability, sustainability and cost, the integrated and continuous production of large-area electromagnetic shielding materials remains unsolved for industrial-scale demands. Herein, we develop a cascaded methodology involving spray loading and Joule-heating for fabricating hybrid EMI fabric with superior efficiency, where ferromagnetic Fe3O4 nanoparticles are further successfully in situ deposition on ultralight carbon fiber felt (Fe3O4/FePc@CFF) in a roll-to-roll (R2R) manner. Fe3O4/FePc@CFF characterized by a surface density of only 64.76 g/m2, achieves specific shielding effectiveness per unit thickness (SSE/t) remarkable values of 9604 dB cm2 g−1 and 10947 dB cm2 g−1 within the X-band and Ku-band, respectively. Considering the high compatibility with assembly on flow line production, this research offers substantial development potential for further design and advancement of pivotal materials in the realm of electromagnetic protection.

Experimental study on mechanical responses of 3D needle‐punched composite preforms at different needling densities: Failure structures, tensile and interlayer peeling strengths

AbstractIn this study, needle‐punched quartz fiber felt / fabrics preforms (NQFFPs) with a wide needling densities (NDs) range from 70 to 280 punches/cm2 were manufactured, then the inner correlation among the NDs, mechanical properties and structural failure modes were studied and revealed. Firstly, the effects of NDs on mechanical strengths, which included tensile and interlayer peeling strengths of NQFFPs, were analyzed through experimental methods. Moreover, MATLAB software was applied to fit the NDs‐mechanical strength curves, then best fitting equations were defined to characterize the change rules between NDs and mechanical strengths. Additionally, with NDs increment, tensile strengths decreased from 0.727 to 0.0925 MPa, whereas interlayer peeling strengths increased from 83.46 to 135.04 N/m. Afterwards, the 3D image technology was utilized to capture failure morphologies of NQFFPs at different NDs from tensile and interlayer peeling experiments, which furtherly revealed the failure mechanisms of NQFFPs at different NDs. This work is significant for the engineering manufacturing and application of needle‐punched preforms and the composites.Highlights Failure structure characteristics of NQFFPs at different NDs were captured. Change rules between NDs and strengths were characterized by math equations. The correlation among NDs, fracture morphologies and strengths was revealed.

Green Energy Production and Integrated Treatment of Pharmaceutical Wastewater Using MnCo2O4 Electrode Performance in Microbial Fuel Cell

The wastewater produced by the pharmaceutical industry is highly organic and toxic. Dual-chambered microbial fuel cells (DMFCs) may represent a sustainable solution to process wastewater while simultaneously recovering its energy content. DMFCs are bio-electrochemical devices that employ microorganisms to transform the chemical energy of organic compounds into electrical energy. This study aims to demonstrate the feasibility of a DMFC with a manganese cobalt oxide-coated activated carbon fiber felt (MnCo2O4-ACFF) electrode to treat pharmaceutical industry wastewater (PW) and exploit its energy content. The proposed technology is experimentally investigated considering the effect of the organic load (OL) on the system performance in terms of organic content removal and electricity production. As per the experimental campaign results, the optimum OL for achieving maximum removal efficiencies for total chemical oxygen demand, soluble oxygen demand, and total suspended solids was found to be 2 g COD/L. At this value of OL, the highest current and power densities of 420 mA/m2 and 348 mW/m2 were obtained. Therefore, based on the outcomes of the experimental campaign, the (MnCo2O4-ACFF) electrode DMFC technique was found to be a sustainable and effective process for the treatment and energy recovery from PW.

Damage behavior of cold-rolled sintered fiber felts

Porous Materials, such as sintered fiber felts (SFFs), can contribute to the reduction of aircraft noise by acting as a low-noise trailing edge (TE). A rolling process with a time-varying rolling gap was sucessfully used to tailor the aeroacoustic properties of SFFs. To ensure the suitability of rolled porous materials for application, the mechanical properties after rolling must be investigated. The objective of this study was to clarify the effect of the rolling process on the damage evolution during tensile loading. A SFF consisting of a functional layer and a support grid made of alloy 1.4404 was used for rolling. Interrupted tensile tests in combination with computed tomography (CT) were used to investigate the damage evolution of as-received material, uniformly rolled material and material rolled with a gradient in thickness reduction. Metallographic examination and fracture surface analysis using scanning electron microscopy (SEM) complemented the CT analysis. Uniformly rolled material with a low degree of deformation (−0.74 ≤ φ < 0) failed identically to the as-received material. The functional layer failed first, starting from the center. The support grid subsequently failed due to the incremental failure of individual wires. The material rolled with a gradient in thickness reduction failed accordingly. A significant change in damage evolution occured for material rolled at high degrees of deformation φ ≤ −1.53, where the support grid fails first and the functional layer second. The rolling process using a time-varying rolling gap does not result in a detrimental mechanical behavior under tensile load. The results improve the general understanding of the effects of rolling processes on the properties of porous materials and allow the damage behavior to be taken into account with regard to its application as a TE.

Preparation and Properties of Elastic Mullite Fibrous Porous Materials with Excellent High-Temperature Resistance and Thermal Stability.

Mullite fiber felt is a promising material that may fulfill the demands of advanced flexible external thermal insulation blankets. However, research on the fabrication and performance of mullite fiber felt with high-temperature resistance and thermal stability is still lacking. In this work, mullite fibers were selected as raw materials for the fabrication of mullite fibrous porous materials with a three-dimensional net structure. Said materials' high-temperature resistance and thermal stability were investigated by assessing the effects of various heat treatment temperatures (1100 °C, 1300 °C, and 1500 °C) on the phase composition, microstructure, and performance of their products. When the heat treatment temperature was below 1300 °C, both the phase compositions and microstructures of products exhibited stability. The compressive rebound rate of the product before and after 1100 °C reached 92.9% and 84.5%, respectively. The backside temperature of the as-prepared products was 361.6 °C when tested at 1500 °C for 4000 s. The as-prepared mullite fibrous porous materials demonstrated excellent high-temperature resistance, thermal stability, thermal insulation performance, and compressive rebound capacity, thereby indicating the great potential of the as-prepared mullite fibrous porous materials in the form of mullite fiber felt within advanced flexible external thermal insulation blankets.

Formulating Superhydrophobic Coatings with Silane for Microfiber Applications

This study investigates the development of superhydrophobic coatings on microfiber surfaces, with a specific focus on cotton, tweed, felt, and polyester fabrics. The resulting coatings demonstrated significant hydrophobicity, with water contact angles ranging from 128.5° for polyester to 148.9° for tweed. In addition, this investigation delves into the influence of pH levels on water contact angles, revealing notable fluctuations; specifically, higher pH levels resulted in decreased contact angles. The results indicated that the tweed fabric had the highest water contact angle at 151.7°, observed at a pH of 4. This study not only underscores the effective hydrophobic performance of these coatings but also highlights their practical applications. In particular, the research demonstrates the potential use of superhydrophobic coatings in the construction of traditional Kazakh ui (yurts), especially emphasizing the promising water repellency properties of felt fibers. Furthermore, this research illustrates a promising approach for producing superhydrophobic coatings on various microfiber surfaces, underlining their extensive potential applications within the textile industry. Overall, the findings suggest that the innovative use of superhydrophobic coatings can significantly enhance the water resistance of traditional and modern fabrics, paving the way for their broader application in various industries, including outdoor textiles and protective clothing.

Supertough MXene/Sodium Alginate Composite Fiber Felts Integrated with Outstanding Electromagnetic Interference Shielding and Heating Properties.

The development of multifunctional MXene-based fabrics for smart textiles and portable devices has garnered significant attention. However, very limited studies have focused on their structure design and associated mechanical properties. Here, the supertough MXene fiber felts composed of MXene/sodium alginate (SA) fibers were fabricated. The fracture strength and bending stiffness of felts can be up to 97.8 MPa and 1.04 N mm2, respectively. Besides, the fracture toughness of felts was evaluated using the classic Griffith theory, yielding to a critical stress intensity factor of 1.79 . In addition, this kind of felt presents outstanding electrothermal conversion performance (up to 119 °C at a voltage of 2.5 V), high cryogenic and high-temperature tolerance of photothermal conversion performance (-196 to 160 °C), and excellent electromagnetic interference (EMI) shielding effectiveness (54.4 dB in the X-band). This work provides new structural design concepts for high-performance MXene-based textiles, broadening their future applications.