Felt Composites Research Articles

Eco-Friendly and Biocompatible Material to Reduce Noise Pollution and Improve Acoustic Comfort in Healthcare Environments

Noise pollution negatively impacts people’s mental and physiological health. Unfortunately, not only is noise present in hospital environments, but its level frequently exceeds recommended thresholds. The efficacy of passive acoustic absorbers in reducing indoor noise in these scenarios has been well-documented. Conversely, given their inorganic composition and their origin in the petrochemical industry, most of these materials present a risk to human health. Over the last few years, there has been a notable increase in research on eco-friendly, low-toxicity, and biocompatible materials. This work outlines a methodology for fabricating recycled acoustic panels from plastic bottles and PET felt composites. This study encompasses three key objectives: (i) a comprehensive biocompatibility assessment of the panels, (ii) an evaluation of their thermal and acoustic properties, and (iii) their applicability in several case studies to evaluate potential acoustic enhancements. Specifically, antifungal resistance tests, Volatile Organic Compound (VOC) emission assessment, and cell viability experiments were conducted successfully. Additionally, experimental procedures were performed to determine the thermal conductivity and thermal resistance of the proposed material, along with its sound absorption coefficients in diffuse field conditions. Finally, the potential benefits of using this biomaterial in healthcare environments to reduce noise and improve acoustic comfort were demonstrated.

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

Negative emission 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 °C to 12 °C decreased sorption performance of the composite felts by 40%.

Copper Sulfide and Graphite Felt Composites as Promising Electrode Materials for Sodium-Ion Batteries.

The most prominent and widely used electrical energy storage devices are lithium-ion batteries (LIBs), which in recent years have become costly and deficient. Consequently, new energy storage devices must be introduced into the current market. Sodium-ion batteries (SIBs) are starting to emerge as a promising solution because of sodium's abundance and low cost. To offer these batteries into the current market, their properties must match surpass those of LIB predecessors, necessitating the need for research in this field. In this research work, three methods of graphite felt (GF) and copper sulfide (CuxS) composite preparation using a hydrothermal approach have been explored and compared. The obtained samples exhibited different morphologies and thermal properties when different hydrothermal composite preparation methods were used. The areal charge capacitance values of these samples differed from 8.81 to 13.65 mF/cm2, and the areal discharge capacitance values differed from 10.06 to 13.65 mF/cm2. Notably, these achieved values are higher than those of the CuxS and GF single substances.

Comparative Study on the Fatigue Behavior of Jute-Wool Felt/Epoxy Hybrid and Glass Fiber/Epoxy Composite

<div>Currently, there is a growing tendency to incorporate natural fibers in composites due to their affordability, lightweight nature, and eco-friendliness. Researchers are continuously exploring new materials that offer improved mechanical properties for a broader range of applications. In this work, an experimental investigation on tensile and fatigue behavior of jute-wool felt-reinforced epoxy hybrid laminate is carried, in addition to an E-glass fiber-reinforced epoxy laminate that helps in comparison. Constant amplitude tensile fatigue test is conducted for 80%, 70%, and 60% of the ultimate load of respective composites at a stress ratio of 0.1 and frequency of 7 Hz for both laminates. The jute-wool felt composite showed good fatigue resistance. Though glass fiber composite showed higher tensile strength, jute-wool felt composite exhibits higher fatigue performance than glass fiber composites at higher stress levels. However, at lower stress levels, glass fiber composite shows better fatigue resistance than jute-wool felt composite. A prediction model that uses a few set of experimental results of fatigue test was able to validate the fatigue behavior of composites. The optical microscope images of failed samples were analyzed to detect the damage in composites.</div>

Low-temperature Synthesis of Carbon Nanofibers/graphite Felt Composites Under Contactless Induction Heating

In this report induction heating was used for the catalytic chemical vapor decomposition synthesis of carbon nanofibers (CNFs) on Ni-based catalyst. The CNFs were produced with a high yield at a relatively low temperature compared to that observed for conventional heating through convection and conduction. The process also occurred in the absence of secondary toxic organic compounds, formed through side reaction in the high temperature gas-phase or through decomposition on the hot wall of reactor as encountered with traditional Joule heating mode. The improved CNFs yield under induction heating was attributed to the high reaction temperature control thanks to the high temperature regulation rate provided by the induction heating coil. The local heating of the nickel nanoparticles by the electromagnetic field could also contribute to the improvement of the CNFs yield. The results obtained indicate that inductive heating mode could be of great interest for improving the heat transfer in catalytic processes and also to reduce the problem of gradient temperature occurring inside the catalyst bed during the operating of highly exothermic or endothermic processes. It is expected that such electricity-driven heating mode could have contributed in an efficient way toward the electrification of different catalytic processes in order to reduce the associated carbon footprint.

Electrical Resistivity and Microwave Properties of Carbon Fiber Felt Composites

We present studies on the microwave properties, electrical resistivity, and low-frequency (10 Hz-20 kHz) noise characteristics in the temperature range of 78 K to 380 K of composite materials made from bisphenol A-based epoxy resin and carbon fiber felts. Two types of carbon fibers were used, derived from polyacrylonitrile or regenerated cellulose. We show that these structures are suitable for electromagnetic shielding applications, especially in the direction parallel to the carbon fibers. The low-frequency voltage fluctuations observed in these materials are of the 1/fα, and the noise intensity is proportional to the square of the voltage. The characteristics of the investigated materials show an instability in the temperature range from 307 K to 332 K. This effect is followed by an increase in resistivity and noise intensity, but it does not change the character of the noise, and this instability vanishes after a few repeated heating and cooling cycles.

Effects of sol contents and sintering temperatures on SiO2 coated needled carbon fibre felt composites

ABSTRACT Carbon fibre has excellent mechanical properties at high temperatures but weak oxidation resistance. The paper prepared the anti-oxidative silica coating on the surface of needled carbon fibre felt by the sol–gel method and discussed the effects of sol content and sintering temperature on the coatings’ performance. The phase composition, density, thermal conductivity and thermal stability of derived composites were characterised, and the structure and morphology of SiO2 coatings were also analysed by scanning electron microscopy. The results indicated that a uniform and complete coating could be formed on the fibre surface when the sol content exceeds 20%. Ceramic particles sintered below 1200°C were amorphous silica, while those sintered at 1350°C were cristobalite. Compared with other processes, 20% silica sol content or sintering at 1350°C could provide better antioxidant protection. The new coating process is significant for retarding fibre oxidation in a high-temperature environment.

Electrode Materials for Enhancing the Performance of a Zinc Iodide Flow Battery at High Current Density

The zinc-iodide flow battery (ZIFB) has a high energy density and uses a benign electrolyte material [1]. However, the energy density and cyclability the ZIFB is hindered by zinc dendrite growth and electrode polarization in this battery [2]. In our previous work a new flow field design was used to mitigate dendrite formation and enhance the performance of the ZIFB [3]. Despite the enhancement achieved, capacity fade and limited cyclability at current densities greater than 20 mA cm- 2 remain a challenge for ZIFBs. In this study, the use of a high electrical conductivity material for the negative (zinc) electrode, combined with an electrocatalyst on the positive (iodide) electrode was investigated, in order to improve the cyclability and energy density of the ZIFB at high current densities.The use of a high electrical conductivity electrode has been shown to enable rapid transfer of surface charge, and maintain a uniform interfacial electric field [4]. A uniform interfacial electric field can reduce surface charge accumulation and enable a more uniform zinc deposition [5]. This leads to uniform zinc deposition and high rechargeability of the zinc electrode. In this study a copper foil was used as a high conductivity electrode material at the negative (zinc) side of the ZIFB. Scanning electron microscopy (SEM) images of the zinc deposit show that epitaxially layered deposition was obtained on the electrode surface. For all the experiments, charge/discharge of a Zn-I battery were carried out using a 3.0 M ZnI2 electrolyte on both sides of the battery, the charge and discharge current density was 40 mA cm-2, and charging was carried out to 60% state of charge. A Nafion 117 membrane was used to separate the electrolyte compartments.Nitrogen doped carbon obtained by carbonizing polyaniline (PANI) is a promising electrocatalyst material for the next generation energy storage technologies [6]. A carbonized PANI-graphite felt composite was used as the electrode material on the positive (iodide) side of the ZIFB. PANI was uniformly coated on graphite felt using brush, followed by heating to 850 °C for 2 hours under the N2 atmosphere. The use of the carbonized PANI modified graphite felt electrode material in the positive side of the ZIFB (with a graphite felt negative electrode), led to an enhancement of the energy efficiency of around 4% (from 67 % to 71%) at a current density of 40 mA cm-2. The carbonized-PANI modified electrode was characterized using X-ray diffraction, Raman spectroscopy, nitrogen adsorption, and SEM. SEM results indicated that agglomerated nano-grains of carbonized PANI were distributed on the graphite felt fibers. Nitrogen adsorption analysis confirmed that the carbonized PANI-graphite felt electrode had a higher specific surface area than the pristine graphite felt.The performance of a ZIFB using a carbonized PANI-graphite felt positive electrode, and a copper foil negative electrode was evaluated by cycling for over 100 cycles. Stable cycling was observed, with a coulombic efficiency of 99%. When compared with using pristine graphite felt on the negative and positive electrodes, a significant improvement in the charge-discharge energy efficiency of around 10 % (from 67 % to 76%) was obtained.

Characterization of a polyaniline/pre-oxidized fiber felt electromagnetic wave absorbing composite

Firstly, a polyaniline/pre-oxidized fiber felt composite was prepared by in situ polymerization using pre-oxidized fiber felt as the substrate, aniline as the monomer, ammonium persulfate as the oxidant, and p-toluenesulfonic acid as the dopant. Secondly, the electromagnetic wave absorbing property and tensile property of the polyaniline/pre-oxidized fiber felt composite were investigated. Finally, the structure and composition were characterized by Fourier transform infrared spectroscopy, Raman spectroscopy, X-ray diffraction, and differential scanning calorimetry. The results show that the reflection loss of the polyaniline/pre-oxidized fiber felt composite is the smallest at the 3000 MHz frequency, reaching –8.23 dB, and the average surface resistance is 2059.84 Ω, with good conductivity. The characterization analysis shows that polyaniline has been successfully loaded on the pre-oxidized fiber felt, and the protonation reaction occurs at the nitrogen atom on the imine -N-. The polyaniline structure is doped by p-toluenesulfonic acid with a certain degree of order and crystallinity, and the composite has good thermal stability.

Development of textile nanocomposites with thermal energy storage capability

In this study, textile-based composites with dynamic heat storage capability have been designed and developed, in addition to their existing passive insulation capacity. First, poly(acrylonitrile) (PAN) shell and poly(ethylene glycol) (PEG1000 or PEG1500) cores are produced by coaxial electrospinning. Then, these are incorporated into felt based composite structures, which demonstrate enhanced thermal properties as well as buffering function against temperature changes in the environment. The thermal energy absorption and release capacities of the felt composites including PAN-PEG1000 or PAN-PEG1500 nanowebs are measured as high as 81 Jg -1 between 33 oC and 46 oC, and 48 Jg -1 between 46 oC and 54 oC respectively. Felt composites, combined with PAN-PEG nanowebs offer forthcoming production applications in the field of dynamic thermal management in various industries.

Study of the Dielectric Properties and Conductivity of Double Coated Glass Fibre Felt Composites

Graphite/talcum powder double-coated glass fibre felt composites were prepared using glass fibre felt as the base material, graphite as the surface absorbing agent, talcum powder as the underlying absorbing agent, epoxy resin E44 as the adhesive and low molecular 650 polyamide as the curing agent. The influences of the surface graphite content and underlying talcum powder content on the dielectric properties and conductivity of glass fibre felt composites were the main focus of the investigation. Results showed that when the frequency is less than 103 Hz, the values of the real and imaginary parts of the dielectric constant for double-coated glass fibre felt composites are largest when the surface graphite content is 50%. When the frequency is larger than 106 Hz, the value of the real part of the conductivity is largest when the graphite contents are 40% and 50%. When the frequency is less than 104Hz, the real part of the dielectric constant of the glass fiber mat composites is the largest when the talc content is 40%, and when talc content is 60%, the imaginary part of dielectric constant of glass fiber mat composites is the largest. The maximum loss tangent value for the composites occurs when the talcum powder content is 40%. When the frequency is larger, the value of the real part of the conductivity increases gradually.

The study on the electromagnetic properties of polyurethane coated pre-oxidized fiber felt composites

In this study, coated pre-oxidized fiber felt composites were prepared using the PU2540 polyurethane as a matrix and adopting a coating technology on the pre-oxidized fiber felt. Firstly, influences of wave-absorbing functional particles on the dielectric properties and shielding effectiveness of single-layer coated pre-oxidized fiber felt composites were analyzed and compared. Secondly, influences of the graphene content on the dielectric properties and shielding effectiveness of graphene coated pre-oxidized fiber felt composites were discussed. Results showed that values of the real and imaginary parts and loss tangent value of the dielectric constant for graphene coated pre-oxidized fiber felt composites were all larger than those of graphite coated pre-oxidized fiber felt composites, that is, the former had a stronger polarization ability, dissipation ability and attenuation ability to electromagnetic waves than the latter. However, the shielding effectiveness of the latter was larger than that of the former, that is, the shielding ability of graphite coated pre-oxidized fiber felt composites was better than that of graphene coated pre-oxidized fiber felt composites. When the graphene content was 15% of the mass of the polyurethane, the value of the imaginary part and loss tangent value of the dielectric constant for graphene coated pre-oxidized fiber felt composites were both the largest, and the dissipation ability and attenuation ability to electromagnetic waves were both the strongest.

Electrochemical synthesis and structural characterization of nanostructured V[formula omitted]O[formula omitted].nH[formula omitted]O on CNTs coated/uncoated carbon felt composite

Amorphous V2O5.nH2O nanostructures (Ns) on CNTs coated/uncoated carbon fibre felt are very attractive electrodes for various electrochemical devices. In present article, we report the morphological and structural characterizations of electrodeposited V2O5.nH2O (denoted as δ-V2O5) phase on defective CNTs coated/uncoated graphitic carbon fibre felt using micro-Raman scattering, TGA curves, SEM and XPS techniques. Using electrochemical methodology, we obtained a highly stable superficial hydrated V2O5.nH2O (n ∼ 0.5) Ns on the surface of bare carbon fibre felt and defective CNT/carbon fibre felt composite. The intercalated hydroxide/H2O bonds are stable till 350°C temperature on both CNTs coated/uncoated felt substrates, which can be extracted from V2O5.nH2O structure using high laser power (≥ 10 mW). After de-hydration of V2O5.nH2O Ns, the local structural phase inclined to ε-V2O5. The surface morphological modification from flat to wrinkle like patterned of V2O5.nH2O Ns depends on electrodeposition parameters (current and time), while the CNT provokes the formation of a V2O5.nH2O layer on CNT/felt fibres with larger degree of roughness, hydration and thickness than in case of bare felt fibres. The proportion of oxidation-state (V+5∕+4∕+3) is barely influenced by CNT presence. Moreover, the electrodeposited V2O5.nH2O layer on graphite felt occurs heterogeneously on the carbon fibre electrode surface, unlike CNT/felt. On the other hand, the crystallite size (La) of micrometric felt and CNT/felt with and without V2O5.nH2O nanostructures are calculated, demonstrating that the adherence of V2O5.nH2O Ns is better on CNT coated felt than bare felt surface, which improved the crystalline properties of nanocarbons as well.

Study on the Thermal Insulation Performance of PAN Pre-Oxidised Fibre Felts

In this paper, an orthogonal experiment of 3 factors and 3 levels was firstly designed to prepare PAN pre-oxidised fibre felts with good thermal insulation properties; the range method was used to analyse the result of the orthogonal experiment, and finally the tensile properties and thermal stability were tested. Finally, pre-oxidised fibre felt composites for the coating of silica aerogel were prepared using the coating process to compound silica aerogel on re-oxidised fibre felts. Firstly, the influence of the content of silica aerogel on the heat insulation performance of the coated composite materials was analysed, and then a test of the coefficient of thermal conductivity, an experiment on the back temperature, and characterisations of the tensile properties and thermal stability of the composite coating of pre-oxidised fibre felt composites of the coating of silica aerogel were carried out. Results showed that through analysis of the orthogonal experiment, we can state that the best preparation process of pre-oxidised fibre needled felts was as follows: needle number – 2, needle depth – 8 mm, and needle frequency – 140 times/min. The transverse tensile strength of PAN pre-oxidised fibre needled felts prepared by crossly webbing of PAN pre-oxidised fibres was superior to the longitudinal tensile strength; thermogravimetric analysis showed that the pre-oxidised fibre needled felts had excellent thermal stability. The coefficient of thermal conductivity of the aerogel coating of the composites firstly decreased and then increased with an increase in the content of aerogel. Coated composites had the lowest coefficient of thermal conductivity when the aerogel content was 4% wt. At temperatures of 100 °C, 150 °C and 200 °C, the heating rate of the transient-state back temperature and the steady-state average temperature were both the lowest when the aerogel content was 6% wt.

Improved chiral electrochemical recognition of tryptophan enantiomers based on three-dimensional molecularly imprinted overoxidized polypyrrole/MnO2 /carbon felt composites.

A three-dimensional molecularly imprinted overoxidized polypyrrole/MnO2 /carbon felt (MIOPPy/MnO2 /CF) composites were fabricated, which results in increased active area of the surface of the molecularly imprinted polymers film and greatly improved electrochemical chiral recognition effect for tryptophan isomers. The composites were characterized by field emission scanning electron microscope, transmission electron microscope, X-ray diffractometer, UV-visible spectra, N2 adsorption-desorption isotherms, and electrochemical methods. The manuscript provides a proof of concept and shows promising potential of the prepared composites for chiral recognition.

Extraordinary air water harvesting performance with three phase sorption

Water scarcity is a current concern and a future problem. Air-water harvesting (AWH) is a novel proposed solution to provide enough water for human-being's needs especially in remote areas. However, the sorbent material is one of the challenging components of these systems. Generally, a proper sorbent must have a high water uptake capacity, a low regeneration temperature and an easy replacement structure, suitable to deploy in the bed. Here we synthesized three active carbon felt composites with a layer structure and analyzed their potential for being used in AWH systems. The performance of these ACFs composites concerning three different salts was investigated. Experimental results showed that the highest capacity is 2.9 g water per g sorbent at 70% of RH without any leakage. Also, pore parameters, non-equilibrium and equilibrium adsorption, regeneration temperature, recyclability and thermal diffusivity of samples were tested. The thermodynamic cycle of the system is studied, and a three-phase sorption cycle is proposed in this study. The detailed analysis reveals that the presence of the combined use of adsorption-absorption process can improve the sorption capacity extensively. The experimental and theoretical studies proved that these composites are very promising materials for water harvesting applications. To demonstrate these materials capability, a prototype is proposed which adopts these materials as its desiccant. This small prototype automatically could harvest 1.51 g of fresh water per cycle per g of sorbent at RH of 70%, without any human involvement.

Multilayered epoxy/glass fiber felt composites with excellently acoustical and thermal insulation properties

ABSTRACTIn this article, a series of epoxy composites consisting of multilayered ultra‐fine glass fiber felts (GFFs) were produced by a hand lay‐up process. The incorporation of GFFs greatly enhances the sound‐absorption and sound‐insulation properties of epoxy composites. It can be mainly attributed to great numbers of voids introduced into the matrix and the increasing interfacial area between glass fiber and epoxy resin, which is confirmed by scanning electron microscopy results. Furthermore, the thermal insulation performance of epoxy/glass fiber felt (EP/GFF) composites is continuously improved with the growing GFF layer, and meanwhile EP/GFF composites exhibit the satisfactory mechanical property. Such novel EP/GFF composites can serve as promising structural, heat‐insulated, and soundproof materials in many multifunctional systems including buildings, aircrafts, constructions, vehicles, etc. © 2018 Wiley Periodicals, Inc. J. Appl. Polym. Sci.2019,136, 46935.

Ultrafast microwave-assisted synthesis of nitrogen-doped carbons as electrocatalysts for oxygen reduction reaction

A facile and ultrafast microwave-assisted thermolysis approach has been adopted to synthesize hierarchical nitrogen-doped carbon within a very short time. The precursor PANI@carbon felt composite was pyrolyzed in microwave oven for different time (10, 20, 30, 40, 50 s) and denoted as NC-X (X = 10, 20, 30, 40, 50). As for NC-30, nitrogen-doping content is obtained up to 3.62 at% with striking enrichment of pyridinic N as high as 45% of the total nitrogen content. Raman analysis indicates the extent graphitization level for the resultant NC-30 and the relative intensity ID/IG was 1.26. High nitrogen-doping content and graphitization level provide effective active sites and efficient electron transfer channel. The resultant NC-30 exhibits pronounced ORR activity with an onset potential of 0.94 V (versus RHE), half-wave potential of 0.80 V and diffusion limiting current density of −5.23 mA cm−2, comparable to those of the commercial Pt/C. It also shows enhanced stability with current retention of 98.3% over 7.5 h as well as superior tolerance against methanol. The simple preparation and excellent ORR performance of NC-30 suggest its promising practical application.

Retracted: Electroadsorption Desalination with Carbon Nanotube/PAN-Based Carbon Fiber Felt Composites as Electrodes.

[This retracts the article DOI: 10.1155/2014/253713.].

Novel carbon felt composites with pyrocarbon deposited on carbon fiber: Hierarchical microstructure for improved phenol-adsorption

ABSTRACTCarbon felt composites were prepared by chemical vapor deposition (CVD) method using Ni(NO3)2 as a catalyst and methane as a pyrocarbon precursor. The pyrocarbon which has been deposited on fiber surface increased gradually with increase in deposition temperature. Besides, the surface of the deposited pyrocarbon was seen to contain many micropores. The phenol-adsorption capability evaluation of the composites showed that the adsorption equilibrium was achieved in 90 min, and the maximum adsorption quantity reached was 13.37 mg/g. The Langmuir isotherm model was preferred in fitting the adsorption data compared with the Freundilch isotherm model. The theoretical maximum adsorption was calculated to be 17.45 mg/g. At pH = 5, the adsorption quantity was a minimum of 10.66 mg/g. Moreover, the phenol-adsorption quantity increased with increasing deposition temperature. The adsorption quantity on carbon felt composites without pyrolytic carbon deposition was minimum, being 9.11 mg/g, while that of carbon fiber produced at 950°C reached the maximum of 13.37 mg/g.