Nanofiber Webs Research Articles

Microwave absorption characterization and wettability of magnetic nano iron oxide/recycled PET nanofibers web

This paper describes the microwave characterization and wettability of a uniform and light magnetic nanofibers web. Iron oxide nanoparticles/recycled poly (ethylene terephthalate) nanofibers web (Fe3O4 NPs/RPET NFs web) were fabricated from bath-sonication solution via electrospinning method. For environmental conservation and economic reasons, RPET instead of virgin material was used. After synthesizing magnetic Fe3O4 NPs with an average diameter of 35 nm by precipitation method using iron sulfate and sodium hydroxide, Fe3O4 NPs/RPET NFs web was made. The main objective of this work is to show how Fe3O4 NPs are able to significantly modify electromagnetic properties at X-band frequencies. Microwave characterization is based on the microwave scattering parameters measured in the X-band (8–12 GHz). Various characterization methods, including field emission-scanning electron microscopy (FE-SEM), X-ray diffraction (XRD) and vibrating sample magnetometer (VSM), have been used to study morphologies, crystalline structure, magnetic, and wettability properties of NFs web. The saturation magnetization of the Fe3O4 NPs/RPET NFs web at a concentration of 5% was 2.79 emu/g. The mathematical model was estimated for magnetization, diameter and concentration by MathWorks Model Predictive Control Toolbax Software. The wettability, reflection coefficient, absorption coefficient, and EMI shielding of Fe3O4 NPs/RPET NFs web have been improved compared to RPET NFs web.

Electrospun polyacrylonitrile–lauric acid composite nanofiber webs as a thermal energy storage material

Phase-change materials have remarkable characteristics due to their simple phase-changeable nature. Within a certain temperature range, these materials can easily change from solid phase to liquid phase or vice versa. It is possible to build thermal energy storage mechanisms, thanks to their latent heat. In this study, composite nanofiber structures were prepared with lauric acid and polyacrylonitrile blends. Nanofiber webs were fabricated via electrospinning technique and combined with phase-change material due to their light weight and high surface area. Thermal energy storage properties were investigated via differential scanning calorimeter, and structural analysis was studied by Fourier transform infrared–attenuated total reflection spectroscopy. Scanning electron microscope was used to investigate the surface morphology of the fibers. Blended polyacrylonitrile–lauric acid nanofibers were successfully converted to nanofiber formation without losing their properties. Results showed that fabricated polyacrylonitrile–lauric acid composite nanofiber webs can be used as a thermal energy storage patch.

Novel Approach for Nanobiocomposites by Nanoencapsulation of Lecithin-Clove oil within PVA Nanofibrous Web

Abstract A facile strategy to fabricate nano within a nano architect material for dental application has been reported. The major complications in dental surgeries is severe blood loss and microbial infection, which causes serious health problems and delay in dental treatment. Microorganisms gain entrance to the blood and circulate throughout the body and cause infection. In this study, we design and develop a bioactive nanofibrous material with multiple features such as analgesic and infection resistance by using a herbal moiety. These nanowebs comprised the nanoparticles of lecithin and clove oil which dispersed in Tween-20 and polyvinyl alcohol nanoemulsion and here finally electrospun to develop nanomat which can be used as a potential candidate in dental applications.

A review on advanced nanofiber technology for membrane distillation

The importance of the nanofiber webs increases rapidly due to their highly porous structure, narrow pore size, and distribution; specific surface area and compatibility with inorganics. Electrospinning has been introduced as one of the most efficient technique for the fabrication of polymeric nanofibers due to its ability to fabricate nanostructures with unique properties such as a high surface area and porosity. The process and the operating parameters affect the nanofiber fabrication and the application of nanofibers in various fields, such as sensors, tissue engineering, wound dressing, protective clothes, filtration, desalination, and distillation. In this review, a comprehensive study is presented on the parameters of electrospinning system including applications. More emphasis is given to the application of nanofibers in membrane distillation (MD). The research developments and the current situation of the nanofiber webs in MD are also discussed.

Fabrication of electrospun chitosan/cellulose nanofibers having adsorption property with enhanced mechanical property

Chitosan/cellulose (CS/CL) nanofibers were fabricated through electrospinning with a mixture of chitosan (CS) and cellulose acetate (CA) in a co-solvent system (trifluoroacetic/acetic acid) and afterward Na2CO3 treatment was followed. The treatment induces the neutralization of CS and deacetylation of CA, converted into cellulose (CL). The CS/CA nanofiber webs maintained the fibrous structure after treatment (converted into CS/CL nanofibers), which cannot be achieved by CS nanofibers. In addition, the combination of CS and CA enhanced the mechanical properties of the resultant nanofibers up to approximately 17 MPa in tensile strength and 5.5% in elongation at break. More importantly, the resulting nanofibers showed adsorptive characteristics; whereas, CL nanofibers showed no adsorption behavior. The incorporation of CS with CL offers the metal ion adsorption property to the composite nanofibers and gives them a waterproof property, which could be utilized in wastewater purification. The adsorption capacity of CS/CL nanofibers for As(V), Pb(II) and Cu(II) ions reached up to 39.4, 57.3 and 112.6 mg/g. Therefore, this nanofiber system showed effective removal behavior in aqueous solution with reasonable mechanical strength, unattainable with pure CS or CL nanofibers.

Electrospinning – 100 Years of Investigations and Still Open Questions of Web Structure Estimination

Abstract The article presents an overview of electrospinning process development from the first investigations in the field of behaviour of liquids in an electrostatic field to the electrospinning methods and investigations in the 21st century. The article presents the history of electrospinning process development, the main problems that are solved, and also indicates the gaps in the field of standardisation of nanofibrous web structure measurement and estimation. There are a lot of works in which authors analyse influences of various parameters on the electrospinning process or on the structure of electrospun web, whereas the majority of them do not analyse the quality of structure using mathematical criteria. Such a situation leads to different conclusions and makes it impossible to compare various works by different authors. Despite numerous studies in electrospinning, investigations in the electrospun nanofibrous web estimation are not sufficient. Until now, a unique standard method for measuring and estimating the fibre diameter and web porosity has not been developed. The necessity of such a method and standards is obvious, and the lack of such a standard could have a negative influence on the electrospun product introduction into the market.

The essential conditions for developing high electrical conductivity capability in carbon nanofibers

Carbon nanofiber webs have high electrical and thermal conductivity, porosity, surface area and good mechanical properties promising great potential for different applications. In this paper, three types of chemically different polyacrylonitrile (PAN) copolymers were electrospun in various concentrations and nanofibers with average diameter between 220 and 530 nm were produced. After stabilization and carbonization of PAN nanofibers, carbon nanofibers with diameter in the range of 110 to 300 nm were produced. The effects of chemical composition and processing parameters on the formation of the sponge-bond interconnected morphology and electrical conductivity of the carbon nanofibers were studied. The results revealed that the progress of stabilization reactions higher than 98% is inappropriate, whereas the stabilization progress in the range of 87% was considered adequate for the development of a proper structure for obtaining high electrical conductivity during carbonization process. Formation of nanofiber mats in shape of a network interconnected sponge-like structure was believed to be necessary for obtaining much higher electrical conductivity (16.70 S/cm compared to 1.10 and 2.33 S/cm in the case of nanofiber mats without interconnections and sponge-like structure).

Evaluation of aloe vera extract loaded polyvinyl alcohol nanofiber webs obtained via needleless electrospinning

In this study aloe vera liquid extract was added to PVA to obtain nanofiber mats with integrated bioactive compounds. Nanofibers are effective in drug release process and the most cost and time effective way to produce them is through roller electrospinning method. Several concentrations of PVA and aloe vera extract have been prepared, as well as pure 10 wt% polyvinyl alcohol solution to compare their properties. Viscosity and electroconductivity of solutions were measured, atomic force microscopy was used for evaluation of nanofiber mats morphology and diameter measurements, samples were analysed and compared by Fourier transform infrared spectroscopy and mechanical properties of the nanofiber mats were tested.

Assembly of odour adsorbent nanofilters by incorporating cyclodextrin molecules into electrospun cellulose acetate webs

A significant problem in ventilating domestic or commercial kitchens is the removal and separation of volatile compounds which we perceive as strong smells of the sort particularly emitted whilst frying food. In this research, the feasibility of preparing enriched electrospun cellulose acetate (CA)-based nanofibres containing cone-shaped molecules of beta-cyclodextrin (β-CD) for the adsorption of the very strong and sharp aldehyde odour of hexanal, which is a marker for oil and fat oxidation was investigated. A binary solvent system using acetone: DMF (2:1) was shown to be suitable for solution blending of CA with β-CD. Nanofibrous webs were continuously produced and found to be substantially free of defects such as beading, producing fibres with the average diameters of 773 ± 50 nm in the range: 250–1.5 μm. Colorimetry was used to show the entrapment of β-CD in the CA structure. The encapsulation efficiency of β-CD in the fibre structures was typically 85%. FTIR of the electrospun nanofibres examining the fingerprint region of CA indicating no structural changes in the CA during processing. Our results show that electrospun CA fibres embedded with β-CD molecules demonstrate enhanced direct adsorption of model odour material hexanal (up to 80%) indicating feasibility for use in filtration.

Natural Sugar-Assisted, Chemically Reinforced, Highly Durable Piezoorganic Nanogenerator with Superior Power Density for Self-Powered Wearable Electronics.

Natural piezoelectric materials are of increasing interest, particularly for applications in biocompatible, implantable, and flexible electronic devices. In this paper, we introduce a cost-effective, easily available natural piezoelectric material, that is, sugar in the field of wearable piezoelectric nanogenerators (PNGs) where low electrical output, biocompatibility, and performance durability are still critical issues. We report on a high-performance piezoorganic nanogenerator (PONG) based on the hybridization of sugar-encapsulated polyvinylidene fluoride (PVDF) nanofiber webs (SGNFW). We explore the crucial role of single-crystal sugar having a fascinating structure along with the synergistic enhancement of piezoelectricity during nanoconfinement of sugar-interfaced macromolecular PVDF chains. As a consequence, the SGNFW-based PONG exhibits outstanding electricity generation capability (e.g., ∼100 V under 10 kPa human finger impact and maximum power density of 33 mW/m2) in combination with sensitivity to abundantly available different mechanical sources (such as wind flow, vibration, personal electronics, and acoustic vibration). Consequently, it opens up suitability in multifunctional self-powered wearable sensor designs for realistic implementation. In addition, commercially available capacitors are charged up effectively by the PONG because of its rapid energy storage capability. The high performance of the PONG not only offers "battery-free" energy generation (several portable units of light-emitting diodes and a liquid crystal display screen are powered up without using external storage) but also promises its use in wireless signal transmitting systems, which widens the potential in personal health care monitoring. Furthermore, owing to the geometrical stress confinement effect, the PONG is proven to be a highly durable power-generating device validated by stability test over 10 weeks. Therefore, the organic nanogenerator would be a convenient solution for portable personal electronic devices that are expected to operate in a self-powered manner.

Sensitive and selective non-enzymatic glucose detection using electrospun porous CuO–CdO composite nanofibers

Porous CuO–CdO nanofibers with mean diameter of 463 nm and high surface-to-volume ratio were prepared by impregnating electrospun carboxylic-functionalized poly(arylene ether ketone) (PCA-PAEK) nanofibrous webs with metal acetate solution and subsequent calcination. The special morphology was demonstrated to be decided by ion exchange reaction between metal ions and functional groups on polymer. TGA and EDX analysis confirmed that Cd2+ was more readily to react with PCA-PAEK than Cu2+, and the amount of Cu2+ can be decreased by overloading of Cd2+, leading to the degradation of sensing performance. FT-IR proved the existence of the ion exchange reaction and demonstrated the products were highly pure CuO–CdO compounds with EDX and XRD spectra. The products detailedly investigated for direct electrocatalytic oxidation of glucose evaluated cyclic voltammetry and chronoamperometry. CuO–CdO nanofibers modified electrodes exhibited superiorities of good anti-interference, low detection limit and fast response of glucose, attributing to the enhanced conductivity brought by CdO, good electrocatalytic activity brought by CuO and large surface area brought by porous structure. The simple strategy of electrospinning porous nanofibers using PCA-PAEK as templates and combined CuO and CdO with good electrooxidation glucose functions opens a new route to generate novel conductive metal oxide hybrid nanofibers applied for glucose enzymeless sensors.

Optimization of testing parameters for tensile property evaluation of poly(vinyl alcohol) nanofibers webs

ABSTRACTAn optimization study was conducted to understand the influence of thickness, speed of testing, and gauge length (specimen test length) on important mechanical properties of poly(vinyl alcohol) nanofiber webs. Using orthogonal experimental design, experimental trials were optimized for the three testing parameters, which enabled to undertake 25 experiments involving the three variables at five different levels. Polynomial regression equations show that the three variables have interactive influence on the mechanical properties tested. Of the three variables, thickness of nanofiber webs seems to have maximum influence on tensile properties. This study showed that the optimal values for tensile testing of nanowebs are gauge length at 0.50 cm, thickness of nanowebs at 0.10 mm, and speed of testing at 25 mm·min−1. This study will provide an opportunity to establish a standard method for the tensile evaluation of nanowebs involving gauge length, thickness, and speed of testing. © 2018 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019, 136, 47159.

Low‐Temperature and Large‐Scale Synthesis of Carbon Nanofiber Web via Electrospinning and Their Efficient Removal of Cr(VI) Ions

AbstractThe carbon nanofiber web (CNW) has been synthesized by electrospinning of polyacrylonitrile (PAN) and polyvinylpyrrolidone (PVP) co‐polymer precursor solution and a following rather low‐temperature (450 oC) thermal treatment. The effect of PAN to PVP ratios on morphology and structure of nanofibers were investigated. Furthermore, the CNW with the fixed composition (PAN:PVP=5:5) were hydroxylated by NaOH solution (obtained CNW‐03‐OH). The CNW‐03‐OH were evaluated for their adsorption performance with Cr(VI) ions. Effects of the initial pH, contact time and temperature for Cr(VI) adsorption were investigated. Results show that the CNW‐03‐OH has an efficient adsorption capacity of 56.9 mg/g for Cr(VI) ions. Moreover, the adsorption capacity remained up to 55% after five cycles, indicating that the CNW‐03‐OH has a promising in practice for application in Cr(VI) ions adsorption.

Improving piezoelectric and pyroelectric properties of electrospun PVDF nanofibers using nanofillers for energy harvesting application

In this study, it was aimed to increase the piezoelectric and pyroelectric properties of electrospun polyvinylidene fluoride (PVDF) nanofibers simultaneously by using specific nanofillers. Graphene oxide (GO), graphene, and halloysite nanotubes with different concentrations (0, 0.05, 0.4, and 1.6% wt/wt) were combined with PVDF solution and were fabricated in the form of nanofibers through electrospinning. Pyroelectric properties of samples were measured by submerging sealed samples in hot water (360°K) and ice (270°K). The piezoelectric properties of the samples were evaluated through bending tests. The microstructural, mechanical, and thermal properties of the electrospun PVDF nanocomposite were investigated using scanning electron microscope, Instron instrument, and thermogravimetric analysis, respectively. To further support the experimental observations for generating electric voltage in the bended nanogenerator, the PVDF nanogenerator (PNG) was also modeled by a finite element analysis based on the theory of linear piezoelectricity using COMSOL Multiphysics simulation software. Experimental results showed that adding nanofillers could improve the piezoelectric and pyroelectric properties of all samples, associated with the increment of β‐phase in the nanofibers. It was concluded that adding nanofillers could increase pyroelectricity about 50% more than piezoelectricity in pristine PVDF nanofiber web. The PNG containing 1.6 wt% GO showed the highest efficiency in terms of piezoelectricity and pyroelectricity. In addition, the results showed that the ratio of piezoelectric to pyroelectric coefficients was constant (~1.5) and it was independent of the nanofiller type and content. The effect of external force and vibration frequency on the output voltage was also investigated. Increasing the compressive force and vibration frequency caused a greater output voltage. Finally, the fabricated nanogenerator was integrated on insole and elbow to investigate its energy harvesting capabilities from body movement.

Efficient Encapsulation of Citral in Fast-Dissolving Polymer-Free Electrospun Nanofibers of Cyclodextrin Inclusion Complexes: High Thermal Stability, Longer Shelf-Life, and Enhanced Water Solubility of Citral.

Here, we report a facile production of citral/cyclodextrin (CD) inclusion complex (IC) nanofibers (NFs) from three types of CDs (hydroxypropyl-beta-cyclodextrin (HPβCD), hydroxypropyl-gamma-cyclodextrin (HPγCD), and methylated-beta-cyclodextrin (MβCD)) by an electrospinning technique without the need of any polymeric carrier matrix. Self-standing nanofibrous webs of citral/CD-IC nanofibers (citral/CD-IC-NF) with uniform fiber morphology have been successfully electrospun from aqueous solutions of citral/CD-IC. Thanks to the inclusion complex formed with CDs, the efficient preservation of citral (up to ~80%) in citral/CD-IC-NFs was observed. In addition, the citral/CD-IC-NFs have shown ~50% preservation of citral for 15 days at room temperature even though citral has a highly volatile nature. The enhanced thermal stability of citral (~100–300°C) in citral/CD-IC-NFs compared to pure citral (~50–165°C) has been observed. Moreover, citral/CD-IC-NFs tended to disintegrate in water very quickly. To summarize, citral was efficiently encapsulated in citral/CD-IC-NFs, and these citral/CD-IC-NFs have been shown to be fast dissolving. In citral/CD-IC-NFs, citral/CD-ICs have enhanced water solubility of citral along with high-temperature stability and a longer shelf-life.

Effect of argon plasma treatment on hydrophilic stability of nanofiber webs

ABSTRACTThis paper provides a comprehensive analysis of microwave‐induced low‐vacuum argon plasma treatment effects on the hydrophilic stability of various polymeric nanofiber webs. After plasma modification, samples are kept dry at room temperature in a dark place for the experiments, and the wettability of the nanofibers is improved by plasma treatment. The stability of the plasma‐treated hydrophilic nanofiber webs is observed for 55 days using water contact angle measurements. Different polymeric nanofiber webs show different stability. Based on the contact angle measurements, the surface starts to lose hydrophilicity during the first week after plasma treatment. The structural changes are examined by pore size measurements, scanning electron microscopy, and Fourier transform infrared spectroscopy. Two of the selected nanofiber webs are used as microfilters for separation of oily wastewater with a cross‐flow separation unit to measure the effect of the plasma treatment under wastewater. The permeability and selectivity of the plasma‐treated and untreated samples are compared. © 2018 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018, 135, 46751.

An Electrospun Core-Shell Nanofiber Web as a High-Performance Cathode for Iron Disulfide-Based Rechargeable Lithium Batteries.

FeS2 /C core-shell nanofiber webs were synthesized for the first time by a unique synthesis strategy that couples electrospinning and carbon coating of the nanofibers with sucrose. The design of the one-dimensional core-shell morphology was found to be greatly beneficial for accommodating the volume changes encountered during cycling, to induce shorter lithium ion diffusion pathways in the electrode, and to prevent sulfur dissolution during cycling. A high discharge capacity of 545 mAh g-1 was retained after 500 cycles at 1 C, exhibiting excellent stable cycling performance with 98.8 % capacity retention at the last cycle. High specific capacities of 854 mAh g-1 , 518 mAh g-1 , and 208 mAh g-1 were obtained at 0.1 C, 1 C, and 10 C rates, respectively, demonstrating the exceptional rate capability of this nanofiber web cathode.

High‐frequency dielectric analysis of carbon nanofibers from pan precursor at different pyrolysis temperatures

AbstractCarbon nanofibers (CNF) produced from pyrolysis of electrospun polyacrylonitrile (PAN) precursor has received a great amount of attention due to their promising potentials. However, there are limited studies on the electrical properties of the CNF, especially at high‐frequency range. In this study, CNF from PAN precursor were produced by electrospinning technique. Characterizations of the nanofibers were carried out in terms of physical, dielectric, and chemical properties. The stabilization of nanofibers took place at 240°C whilst carbonization process took place at temperatures of 800°C, 1000°C, and 1200°C, respectively. In terms of physical properties, the color of the nanofiber webs changed from white to brown and black, after stabilization and carbonization process accompanied by significant reduction in average fiber diameter. Dielectric analysis of the nanofibers was obtained by measuring the wave propagation characteristics at frequency range of 1 GHz to 10 GHz. Higher dielectric constants of the material were observed for fibers processed at higher carbonization temperatures. Good conductivity was also observed with loss tangent value that is higher than 1. The results were correlated with FTIR transmittance results, indicating greater amount of carbon are present in the nanofiber material. From the findings, the unique behavior of the nanofibers makes it practically potential for sensor applications. Explorations of future research in this area are to be sought.

An investigation on the fabrication of conductive polyethylene dioxythiophene (PEDOT) nanofibers through electrospinning

This article reports on the possibility of the fabrication of conductive PEDOT (3,4 poly ethylene dioxythiophene) nanofibers through electrospinning. Electrospinning of pure PEDOT nanofibers from its solution has not yet become possible. Also in this work, the efforts to electrospin pure PEDOT or pure EDOT nanofibers proved fruitless. Hence, poly(acrylic acid) (PAA)was employed to assist the electrospinning of EDOT. EDOT:PAA nanofibers were collected in an oxidation bath, where in-situ polymerization of EDOT into PEDOT occurred. After a series of experiments, PEDOT/PAA (50:50) and PEDOT/PAA (67:33) nanofibers were successfully fabricated. The lowest average diameter of the PEDOT/PAA nanofibers was around 300 nm. An electrical conductivity of 0.16 S/cm was recorded for the PEDOT/PAA (50:50) nanofibrous web which is a considerable improvement over similar products reported in the literature. X-ray analysis showed that PEDOT/PAA nanofibers have an amorphous microstructure. FTIR analysis showed no reaction or major interactions between EDOT or PEDOT and PAA. Moreover, FTIR analysis proved successful polymerization of EDOT into PEDOT. TEM images indicated a good degree of homogeneity for PEDOT and PAA in PEDOT:PAA nanofibers.

폴리우레탄 나노섬유 웹의 특성에 미치는 폴리도파민 코팅의 영향

전기방사에 의해 제조된 폴리우레탄(PU) 나노섬유 웹의 기능성을 향상시키기 위하여 폴리도파민 수용액으로 코팅하였다. 전자주사현미경을 통하여 PU 웹에 폴리도파민이 균일하게 코팅되었음을 확인하였으며, 추가적으로 표면 분석을 수행하였다. 코팅 전후의 수분 및 공기 투과능, 인장강도 등의 물리적 특성변화는 나타나지 않았고 항균성과 자외선 차단능을 향상시키는 결과를 보였다. 따라서 폴리도파민으로 코팅된 PU 나노섬유 웹이 고기능성 고어텍스 필름의 대체품으로 적용가능성이 있을 것으로 기대된다.