Nanofiber Nonwoven Fabric Research Articles

Water-efficient evaporative cooling by sunlight-reflective radiative-cooling nanofibers

Evaporative cooling, which has the highest potential for energy transfer, is not sustainable without sufficient water. Here we present the membrane that can be used to protect the moisture from unnecessary evaporation. The membrane is composed of nanofiber non-woven fabric that is breathable and has high solar reflectance and high infrared emissivity for water-efficient evaporative cooling applications. The membrane prevents moisture from evaporating unnecessarily by blocking solar absorption and efficient thermal emission. Specifically, the membrane is composed of ∼400 nm diameter polyurethane fiber, which has a high MIE scattering effect on solar radiation (∼2500 nm wavelength), resulting in over 95% solar reflectance as well as over 95% of total infrared (IR) emissivity and IR transmittance at 50 g/m2 of membrane. In addition, it has sufficient breathability of over 16 mg•cm2•hr that the maximum evaporative cooling is about 100 W/m2. Twice the cooling time and 3 °C cooler surface by tandem of radiative cooling were confirmed in outdoor test of wet fabric covered with nanofiber membrane compared to wet fabric without membrane. This scalable and flexible membrane is applicable where the thermal cooling without energy consumption is required for net-zero energy consumption.

Chelating Coordination Regulated Photochromic Electrospun Nanofibers for Waterproof and Long-Color-Retention Rewritable Wearables.

Photochromic materials with rapid color-switching, long color retention times, and rewritability are crucial for meeting the requirements of future rewritable ink-free media. However, these requirements are challenging to satisfy simultaneously due to the inherent constraints among these features. Herein, a novel photochromic nanofiber nonwoven fabric was designed and constructed based on a conjugated organic-inorganic hybrid structure through electrospinning and hot-pressing techniques. The as-prepared fabric can change color in merely 5 s under UV irradiation and can reach saturation within 2 min. In addition, upon the introduction of a potent metal chelator, its color retention time exceeds 14 days under ambient conditions, significantly longer than that of most rewritable materials recently reported (several hours to 5 days). Moreover, the fabric exhibits high writing resolution and can be photoprinted and heat-erased for over 100 cycles while still retaining 96% of its initial reflectivity. Hydrophobic thermoplastic polyurethane provides the fabric with excellent waterproof and antifouling properties, thus preventing the composite from swelling or collecting graffiti due to moisture or dust. This work exploits a competitive approach for designing flexible, rewritable, and superior functional wearables with practical applications.

Estimation of Sound Transmission Loss in Nanofiber Nonwoven Fabrics: Comparison of Conventional Models and the Simplified Limp Frame Model.

Although the sound absorption coefficients of conventional and nanofiber nonwoven fabrics (NF-NWFs) have been the subject of many previous studies, few studies have considered the estimation of transmission loss. Reported herein is an experimental and theoretical study into estimating the transmission loss of NF-NWFs using four estimation models, i.e., the Rayleigh, Miki, and Komatsu models, and the simplified limp frame model (SLFM), with the model results compared against the experimental data. The transmission loss of the NF-NWF was determined from the propagation constant, and characteristic impedance was calculated using the estimation model and the transfer matrix method. The validity of each estimation method was examined by comparing its estimated values with the experimental values measured using a four-microphone impedance measurement tube. The proposed SLFM is more suitable for estimating the transmission loss of NF-NWFs than the conventional Rayleigh, Miki, and Komatsu models.

A study on MMG sensor using piezoelectric polymer nanofibers by electrospinning

AbstractIn the fields of medical and sports science, it is required to evaluate muscle activity qualitatively and quantitatively. Currently, mechanomyogram (MMG) that can reflect the mechanical activity of muscle fibers is attracting attention. The purpose of this study is to develop a sensor that can measure MMG during exercise. In this study, a small and flexible MMG sensor using P(VDF/TrFE), which is a piezoelectric polymer material, spun into nanofibers by the electrospinning method has been fabricated and evaluated. By the fabricated electrospinning equipment and the obtained fabrication conditions of the nanofibers MMG sensor has been fabricated by using piezoelectric polymer fibers. By using nanofiber nonwoven fabric for the sensor element, the flexible sensor has been realized. In a sound wave reception experiment assuming MMG measurement, the P(VDF/TrFE) nonwoven fabric element showed that the element detected the sound pressure. Additionally, MMG during isometric contraction and pedaling motion has been measured using the fabricated sensor. The results show that the proposed sensor is effective for measuring MMG during exercise.

Investigation of Thermal-Insulation Properties of Nano-fiber Non-Woven Fabric by Computational Fluid Dynamics Model Consider Fiber Diameter Distribution

Investigation of Thermal-Insulation Properties of Nano-fiber Non-Woven Fabric by Computational Fluid Dynamics Model Consider Fiber Diameter Distribution

Investigation of Air Filter Properties of Flash-Spinning Nanofiber Non-Woven Fabric

Using computational fluid dynamics (CFD) technology, a stable manufacturing method for polymeric nanofiber non-woven fabrics based on an improved melt-blowing method and flash spinning is realized to achieve mass productivity. Subsequently, a method to predict filter efficiency using two production methods based on the effects of thickness, filling rate, and fiber diameter on filtration performance is developed to establish a filter design via CFD technology. CFD models featuring uniform fiber diameters are proposed. Next, the pressure loss and flow resistivity are calculated using CFD flow analysis software, as in a filter experiment. The proposed fiber diameter distribution model yields results similar to the experimental value, and the relationship among filling rate, fiber diameter, and flow resistivity is verified. The non-woven filter fabricated in this study demonstrates superior filtration properties, based on the results. Additionally, a method to satisfy both low pressure loss (low flow resistivity) and high filtration efficiency is discussed. Although the pressure loss increases, the filter yields a value below the standard for high-performance face masks, since the fiber diameter is on the nano-order.

Simplified Limp Frame Model for Application to Nanofiber Nonwovens (Selection of Dominant Biot Parameters).

This study aimed to discover an easy and precise prediction model for the acoustic properties of nanofiber nonwoven fabrics. For this purpose, a prediction model focusing on the two dominant parameters in the Limp frame model—bulk density and flow resistivity—was suggested. The propagation constant and characteristic impedance was generated from the effective density and effective volume modulus generated by the predictive model and treated as a one-dimensional transfer matrix. The sound absorption coefficient was then estimated using the transfer matrix approach. The trend of the normal Incident sound absorption coefficient measured and the sound absorption coefficient obtained from the predictive model were consistent. Thus, it is suggested that the predictive model for the proposed nanofiber nonwoven composite sheet is valid.

Conductive self-standing nanofiber fabric of fluorine-doped tin oxide prepared by electrospinning for use in flexible electronics

To realize a conductive substrate with heat resistance and flexibility for the application to flexible electronics, we aimed to reduce the resistance of the fluorine-doped tin oxide (FTO) ceramic nanofiber (NF) non-woven fabrics produced by the electrospinning method. Using NH4F and SnF2 as the raw materials for fluorine doping, the structure and electrical properties of FTO-NF non-woven fabric were compared. The non-woven fabrics obtained in both solutions were several cm square made by NFs with a diameter of 150~800 nm, and all NFs consisted of nanoparticles with a diameter of about 20 nm. The resistivity of the FTO-NF fabric could be reduced to $$5.19 ~\mathrm{\Omega \cdot cm}$$ by the improvements such as adding tin isopropoxide and mixing without using water for a solvent without making a precursor of FTO so that the raw material is uniformly adsorbed on the polymer in the solution. By considering the space occupancy of the NFs in the fabric, the minimum net resistivity of the FTO-NF fabric was estimated to be $$0.56 ~ \mathrm{\Omega \cdot cm}$$ . Since the obtained FTO fabric was brittle and cracked when bent, we made a prototype of a three-layer NF non-woven fabric composited with amorphous SiO2 NFs. The sheet resistance was $$6.4 ~\mathrm{k\Omega /sq}$$ , no cracks or breaks occurred even when wrapped around a glass rod with a diameter of 5 mm $$\phi$$ , and the rate of increase in the resistance after 100 bends could be suppressed to 4.9%.

Preparation of pitch/polyacrylonitrile carbon nanofiber non-woven fabrics as the electrode for supercapacitors

Preparation of pitch/polyacrylonitrile carbon nanofiber non-woven fabrics as the electrode for supercapacitors

Preparation of pitch/polyacrylonitrile carbon nanofiber non-woven fabrics as the electrode for supercapacitors

Pitch/polyacrylonitrile carbon nanofiber non-woven fabrics (P/PAN CNFs) for use as supercapacitor electrode materials were prepared by electrospinning a mixed solution of pitch and PAN, followed by stabilization and carbonization. Results indicate that P/PAN CNFs have a smaller fiber diameter, higher conductivity, larger specific surface area and moderate pore size compared with PAN CNFs, which increases the capacitance and rate capability of the supercapacitors. When the mass ratio of pitch to PAN was 1/1.5, the P/PAN CNF (P/PAN-1/1.5) showed a high capacitance of 219 F g−1 at a current density of 0.1 A g−1, a value 1.38 times that of PAN CNF. When the current density was increased to 50 A g−1, the capacitance retention of the P/PAN-1/1.5 was 69.4%, 42.8% larger than that of PAN CNF. A symmetrical supercapacitor based on P/PAN-1/1.5 had an energy density of 4.8 Wh kg−1 at a power density of 14.8 kW kg−1 and a capacitance retention rate of 94.1% after 20 000 cycles.

Investigation of Flow Resistivity of Air Filter by CFD Analysis Model of Nanofiber Non-woven Fabric

Investigation of Flow Resistivity of Air Filter by CFD Analysis Model of Nanofiber Non-woven Fabric

Investigation of Two Patterns Structure Model of Air Filter by CFD Analysis for Nanofiber Non-woven Fabric

Investigation of Two Patterns Structure Model of Air Filter by CFD Analysis for Nanofiber Non-woven Fabric

Investigation of Production of Nanofiber Nonwoven Fabric and its Thermal Properties

Nanofibers of polypropylene were produced by a modified melt-blowing method. The manufacturing method and thermal characteristics of fabricated nonwoven-fabric nanofibers were studied. Apparent thermal conductivity was measured as an evaluation of adiabatic properties, and a prediction model was developed with computational fluid dynamics (CFD) based on a one-dimensional computer-aided engineering method. In addition, we attempted to evaluate true thermal conductivity in consideration of lateral heat dissipation during measurement by thickness. Consequently, we determined the influence of the fiber diameter and thickness of the nonwoven fabric on the thermal conductivity and demonstrated that the proposed CFD model was effective for estimating the characteristics of the thermal conductivity of the nonwoven fabric.

Electrospun Coal Liquefaction Residues/Polyacrylonitrile Composite Carbon Nanofiber Nonwoven Fabrics as High-Performance Electrodes for Lithium/Potassium Batteries

Coal liquefaction residues (CLRs)-based nanofiber nonwoven fabrics are fabricated by electrospinning using the mixture of polyacrylonitrile and preasphaltene (toluene insoluble-tetrahydrofuran solu...

Influence of Magnetite Dispersion on Tensile Properties

Nanofibers have high cell affinity due to their fine structure and surface roughness, and are expected to be used as biomaterials. In particular, magnetic nanofibers containing magnetic particles are expected to be used for magnetically induced drug delivery systems and hyperthermia. However, due to the aggregation of the magnetic particles contained in the nanofibers, there is a problem that the aggregation location becomes a starting point of fracture and causes a decrease in tensile strength. In this study, to improve the dispersibility of magnetic particles in Magnetite/PLA nanofiber nonwoven fabrics for suppressing the decrease in tensile strength, magnetite is subjected to surface treatment with oleic acid or stearic acid and ultrasonic agitation. Magnetite/PLA nanofiber nonwoven fabric was prepared by the electrospinning method, and dispersion of magnetite in PLA nanofiber nonwoven fabric and tensile strength were evaluated. Magnetite dispersion was improved by the surface treatment and increasing the ultrasonic agitation time. In particular, by performing the stearic acid treatment and prolonging the ultrasonic agitation time, the magnetite dispersion tended to be improved. This treated Magnetite/PLA nanofiber nonwoven fabric showed higher tensile strength.

Investigation of Oil Adsorption Performance of Polypropylene Nanofiber Nonwoven Fabric

Nanofibers can be used in fields/applications such as medical care, environment protection, apparel, and agriculture. In addition, we believe that this field would continue to show substantial growth in the future. In this study, we focused on its application to oil adsorption. Oil adsorbing performances achieved polymeric nanofiber mass production by a melt-blowing method. We first tested the oil adsorption performance of fiber experimentally under different bulk densities and thicknesses. We also conducted the suction experiment with different bulk densities. Based on experimental result, we considered contact angle, capillarity, and surface tension to be the causes of oil adsorption. We also proposed a three-direction physical model for oil adsorption and used it to calculate the theoretical oil adsorption rate by different free volumes. As a result, we confirmed that the proposed three-direction model could accurately estimate the oil adsorption rate. Moreover, nanofiber has exceptional oil adsorption performance. Further, the fiber with average diameter of 1500 nm exceeds 60 times its self-weight. Therefore, we believe that the proposed nanofiber nonwoven fabric oil adsorption pad could adequately be used as oil adsorption material.

Investigation of Production of Nano Fiber Non-woven Fabric and Its Oil adsorption and filtration characteristics

Investigation of Production of Nano Fiber Non-woven Fabric and Its Oil adsorption and filtration characteristics

Investigation of Production of Nano Fiber Non-woven Fabric and its Thermal Property

Investigation of Production of Nano Fiber Non-woven Fabric and its Thermal Property

Structure and Feature of Cellulose Nanofiber Nonwoven fabric

Structure and Feature of Cellulose Nanofiber Nonwoven fabric

Selective Adsorption Characteristics of Gold Ions by Nylon Nanofiber Nonwoven Fabric

Selective Adsorption Characteristics of Gold Ions by Nylon Nanofiber Nonwoven Fabric