Superfine Fibers Research Articles

Pyridine Functionalized Polystyrene Supported Cobalt Superfine Fibers as an Efficient and Recyclable Catalyst for Heck Reactions

Pyridine Functionalized Polystyrene Supported Cobalt Superfine Fibers as an Efficient and Recyclable Catalyst for Heck Reactions

Copper Phthalocyanine Functionalized Polystyrene Superfine Fibers for the Photodegradation of Methyl Orange

Copper Phthalocyanine Functionalized Polystyrene Superfine Fibers for the Photodegradation of Methyl Orange

Regenerated cellulose supported palladium composite superfine fibers as an efficient and recyclable catalyst for Suzuki reaction

Regenerated cellulose supported palladium composite superfine fibers as an efficient and recyclable catalyst for Suzuki reaction

Properties and Structure of Thermoplastic Polyvinyl Alcohol/Polyamide Sea-Island Fibers.

Ultra-fine fibers derived from sea-island fibers have attracted great attention due to their excellent overall performance. However, green and efficient splitting of sea-island fibers is still a challenging task. In this work, thermoplastic polyvinyl alcohol (TPVA) was prepared by the physical blending of plasticizer. The modified TPVA showed a high decomposition temperature (285 °C) and a wide thermoplastic processing window. This made TPVA match well with polyamide 6 (PA6) to form conjugated melts at 250 °C. Corresponding PVA/PA6 sea-island fibers were first reported to realize water-splitting instead of alkali-extraction of "sea" polymers. The effects of sea/island mass ratios and different spinning speeds on the properties of PVA/PA6 sea-island pre-oriented yarn (POY) were investigated. A higher spinning speed enhanced the orientation-induced crystalline behavior of fiber, therefore increasing the tensile strength of fibers. As the increase of spinning speed from 1000 to 1500 m/min, the crystalline degree of corresponding POYs increased from 9.9 to 14.3%. The plasticizer in PVA did not diffuse to the PA matrix during spinning. However, PVA could induce the crystallization of PA6 via interfacial hydrogen bonding. When the spinning speed was 1500 m/min, and PVA/PA6 was 7:3, the tensile strength reached the highest value of 1.67 cN/dtex. The uniform diameters of ultra-fine PA6 fibers (2-5 μm) were obtained by an environment-friendly water-splitting process. The "sea" phase (TPVA) in sea-island fiber could be removed quickly by boiling water treatment in 3 min. This green and energy-saving sea-island fiber splitting technique is of great significance in reducing CO2 emissions during the preparation of super-fine fibers.

Preparation and characterization of carex meyeriana Kunthcellulose nanofibers by electrospinning

The cellulose of carex meyeriana kunth (CMKC) was used as raw material, and the spinning solution was prepared by combining with polyacrylonitrile (PAN). The nano-cellulose fiber of carex meyeriana kunth (CMKN) was prepared by electrospinning. Used to remove methylene blue dye (MB) in aqueous solution. In the electrospinning experiment, the addition of CMKC was in the range of 5% ~ 25%, the feed rate of spinning parameters was set in the range of 0.2 ~ 1.0 mL/h, the distance from the needle tip to the collecting plate was in the range of 10 ~ 25 cm, and the voltage was changed in the range of 15 ~ 25 kV. The obtained CMKN was characterized by scanning electron microscope, X-ray diffraction (XRD) and Fourier transform infrared spectroscopy. The MB removal rate was evaluated in the dye removal experiment, and the effects of CMKN on MB removal rate under the factors of CMKC dosage, temperature, shock time and MB initial concentration were discussed. The optimum process conditions were determined by response surface methodology. The results show that the prepared fibers are superfine fibers with nanometer diameter, and the spun nanofibers have smooth surface, high overall orientation and strong uniformity. The adsorption kinetics of prepared CMKN accords with quasi-second order model, and the adsorption isotherm accords with Langmuir model. The maximum dye removal rate of CMKN is 63.24%.

Determination of fipronil and its metabolites in environmental water samples by meltblown nonwoven fabric-based solid-phase extraction combined with gas chromatography-electron capture detection.

In this study, a new method for the determination of fipronil and its three metabolites in environmental water samples was developed based on meltblown nonwoven fabric solid-phase extraction combined with gas chromatography-electron capture detection. As the core material of medical masks, meltblown nonwoven fabric is made of polypropylene superfine fibers which are randomly distributed and bonded together with a relatively large specific surface area and good permeability. Polypropylene as a high molecular hydrocarbon-based polymer has the characteristics of good hydrophobicity and lipophilicity, which can be applied for the separation and enrichment of hydrophobic substances in food, environment, and biological samples. The meltblown nonwoven fabric is soft and can fill the solid-phase extraction cartridge tightly. This aspect also makes it suitable to be used as an ideal solid-phase extraction sorbent. A series of parameters influencing the extraction efficiency were investigated, and under the optimized conditions, fipronil and its three metabolites had a good linear relationship in the range of 0.2-100 μg/L with a correlation coefficient R2 of more than 0.999. The recoveries at three spiked concentrations were in the range of 99.2-107.3% with the relative standard deviations less than 9.8% (intra-day) and 8.1% (inter-day). The limit of detection for the four target analytes was in the range of 0.02-0.06μg/L. Finally, this method was successfully applied in the analysis of fipronil and its three metabolites in various types of environmental water samples.

Characteristics of the Parameters of Superfine Fibers of Poly(3-hydroxybutyrate) Modified with Tetraphenylporphyrin

Structural-dynamic studies combining X-ray diffraction analysis, thermophysical measurements (DSC), X-ray diffraction analysis, probe EPR method, and scanning electron microscopy are performed. The structural and dynamic characteristics of electrospun superfine fibers based on poly-(3-hydroxybutyrate) (PHB) containing a low concentration of the tetraphenylporphyrin complex (TPP) (0–5%) are considered. It is shown that the addition of tetramethylporphyrin complexes to PHB fibers changes the morphology, a slight decrease in crystallinity is observed, and the molecular mobility in the amorphous regions of the polymer slows down. The temperature action on the fibers (annealing at 140°C) leads to a sharp increase in crystallinity and molecular mobility in the amorphous regions of poly(3-hydroxybutyrate)—TPP fibers. Exposure to an aqueous medium at 70°C is accompanied by a sharp decrease in the enthalpy of melting and an increase in the molecular mobility of chains in the amorphous regions of the fiber.

Preparation of lotus nanofibers-alginate porous membranes for biomedical applications

Tissue and organ failure or loss is a major problem for human health, and the construction of tissue engineering porous scaffold materials is a core step in the repair of damaged tissue and organs. Fibers from the lotus (Nelumbo nucifera) plant can be a source of superfine fibers. Such fibers have excellent biocompatibility, and they are easy to convert into nanofibers that could be applied for tissue engineering. Lotus fibers were carboxyl-modified with the TEMPO/NaClO/NaBr system, and lotus nanofibers were prepared. The effect of oxidation conditions on their morphologies and degrees of oxidation were investigated. The diameters of the lotus nanofibers were about 15 nm. Additionally, the degrees of oxidation of lotus nanofibers increased with an increase of oxidation time. Moreover, the oxidized sodium alginate membranes crosslinked with carboxymethyl chitosan degraded quickly, with the degradation rates increased by 82.1% or 100.0% during a 14-day period. By increasing the dosage of carboxymethyl chitosan, the pH values tend to rise. In comparison, the degradation rates of the lotus nanofibers/alginate porous membranes crosslinked with carboxymethyl chitosan exhibited better performance in terms of microstructure, porosity, water absorption, mechanical properties (0.36 MPa /7.7%), and in vitro degradation (59.2%).

Formation of bead‐free and core–shell superfine electrospinning fibers under the assistance of another polymer and an interfacial compatibilizer

This work presents a new way of preparing bead‐free and core–shell superfine polymer electrospinning fibers under the assistance of another polymer and an interfacial compatibilizer. For the electrospinning of polystyrene (PS)/CHCl3 solution, the bead‐free fiber cannot be obtained until the PS concentration is above 0.25 g/mL but its average diameter is above 10 μm. Using polyamide 6 (PA6) as an additive, the critical concentration capable of forming bead‐free fiber greatly decreased and core–shell fibers with PA6 as the core and PS as the shell were obtained due to the driving effect of high spinability of PA6. The introduction of a copolymer (PS‐co‐TMI) of styrene (St) and 3‐isopropenyl‐α,α‐dimethylbenzene isocyanate (TMI) can react with amine of PA6 to form the copolymer of PS and PA6 as an interfacial compatibilizer. As a result, it can further enhance the dispersion and deformation of minor component PA6 into uniform microfiber core, and drive PS to uniformly cover the surface of PA6 fibers, and finally form bead‐free and core–shell superfine fibers. POLYM. ENG. SCI., 59:1437–1444 2019. © 2019 Society of Plastics Engineers

Melt-electrospinning of Polyphenylene Sulfide

Polyphenylene sulfide (PPS) superfine fiber is a promising high efficient material for high temperature dedusting. In this paper, the PPS superfine fiber was prepared by melt-electrospinning for the first time. In order to produce the finer fibers, the polypropylene (PP) was added to PPS and the effects of blending ratio, spinning voltage, spinning temperature, and spinning distance on resultant fibers were investigated systematically. The superfine fibers of PPS with an average diameter of 4.12 μm were successfully prepared at the optimized condition, which was one third of that by melt-spinning method. With the decrease of 76.21 % fibers diameter, the filter efficiency increased from 87.03 % to 98.05 %. The presented method provides a new way for the scalable and green fabrication of PPS superfine fibers.

Palladium immobilized on in situ cross-linked chitosan superfine fibers for catalytic application in an aqueous medium

Chitosan composite superfine fibers with a diameter of 321 ± 99 nm were prepared by electrospinning with PEO as the co-spinning polymer and itaconic acid as the in situ cross-linking agent.

Pd nanoparticles entrapped in chitosan superfine fibers as a highly active and stable catalyst for the Mizoroki–Heck reaction

Pd nanoparticles entrapped in chitosan superfine fibers as a highly active and stable catalyst for the Mizoroki–Heck reaction

Enhanced fluorescence properties of terbium complex/poly-l-lactic acid superfine fibers sensitized by the LSPR effect of silver nanoparticles

Due to the LSPR effect of Ag-NPs, the fluorescence intensity, quantum efficiency of Tb-complex in the composite fibers were improved.

Bioremediation of Dyes Using Ultrafine Membrane Prepared from the Waste Culture of Ganoderma lucidum with in-situ Immobilization of Laccase

A one-step method for laccase production and immobilization using the waste culture of Ganoderma lucidum (G. lucidum) was developed, and the laccase was immobilized by the mycelium, which was in the form of a white membrane consisting of superfine fibers. This medical and edible membrane was characterized by scanning electron microscope (SEM), and the fiber diameter was found to be between 1 and 3 μm, with a porous structure formed in the membrane. Fourier transform infrared spectroscopy (FT-IR) and thermogravimetric analysis (TGA) showed that the membrane contained polysaccharide groups and had good thermal resistivity. The membrane was used for the decolorization of methyl violet and malachite green, while the MTT test showed that the membrane had good biocompatibility. The experimental results indicated that the membrane might be applicable for other environmental protection applications in the future.

Study on uniformity of a melt-blown fibrous web based on an image analysis technique

Abstract Melt blowing is a one-step process to manufacture products with superfine fibers with diameter <5 μm (and even below 1 μm). As an intermediate product, a melt-blown (MB) web provides a strong influence on the functional properties of the final MB products. In this paper, the influence of processing conditions on the uniformity of a MB web is studied using an image analysis technique, including nominal air jet pressure, polymer volume flow rate, air suction velocity, and the moving speed of the collection belt. This study enables us to quantify the influence of the processing conditions on the uniformity of MB fibrous web.

The effect of the nano-structured aerogel powder on the structural parameters, water repellency, and water vapor/air permeability of a fibrous polyester material

A water-glass-based silica aerogel was synthesized through an ambient pressure drying method and its structural parameters, hydrophobic property, and blending with a nanofibrous polyester material were investigated. The hybrid aerogel-fibrous materials were prepared using an electrospinning method and their hydrophobic and water vapor/air permeation characteristics were analyzed using the SPSS software by one-way ANOVA, Duncan, and 1-sample K-S tests. The BET and BJH analyses showed that the nanosilica aerogel has a pore size of 24 nm and a total pore volume of 3.5 m3/g resulted in 88.6% porosity and 0.2 g/m3 density. The silica aerogel granules showed a high water sliding angle, whereas, the aerogel powder-coated water droplets (marbles) showed a sliding angle of as low as 5°. The SEM and AFM analyses indicated the successful embedding of the aerogel powder into the nanofibrous material with an irregular beads–like structure. The most aerogel content of 4 wt% in the hybrid fibrous material showed a lower mean diameter (176.2 nm) as well as a lower mean size of spaces formed between the super-fine fibers (3598.5 nm) in comparison with the fibrous material with no aerogel content. The beaded fibrous structures of the hybrid fibrous materials led to a suitable two-scale surface roughness with an improved water contact angle up to 130.1° in comparison with 103.4° for the one with no aerogel content. The samples surface energy was remained unchanged with 3 M water repellency of 1. Also, there was no significant difference between the water vapor permeability (WVP) of the samples according to the ANOVA tests with P-values of more than 0.05. The super-fine fibers containing 2 and 4% aerogel have a higher permeability to air in comparison to the pure super-fine fibers and the super-fine fibers containing 0.5 and 1% aerogel, which may be due to the recognized effect on the reduction of the fibers diameter as well as smaller empty spaces formed between the super-fine fibers.

Modeling the nanofiber fabrication with the melt blowing annular die

Melt blowing is commonly used to convert polymer resin directly into nonwoven fabrics of superfine fibers. Further decrease of the fiber diameter will improve the filtration and adsorption properties remarkably and thus has been appealing to the researchers. Besides the dual slot die, the annular die is utilized to manufacture superfine fibers in the melt blowing process as well. In the dual slot die, the high velocity air flow from both sides of the polymer melt. However, the air encircles the polymer melt entirely in the annular die, which is in favor of the polymer drawing and thus manufacture of nanofibers. In this paper, the air flow field model of the annular die is established and solved numerically. The polymer drawing with the melt blowing annular die is modeled and simulated by introducing the simulation results of the air flow field. The predicted fiber diameters coincide with the experimental data. Effects of the polymer flow rate and initial air velocity on the fiber diameter are also explored. The results show good perspective of using melt blowing technology to manufacture nanofibers materials because melt blowing has a higher output than electrospinning.

On air blowing direction in the blown bubble-spinning

This paper studies the effect of airflow direction on morphology of the nanofibers obtained by the blown bubble-spinning, a kind of Bubbfil spinning processes. Regenerated silk fibroin is used in the experiment, and the results indicate that nanofibers with random array structure can be obtained when the blowing air direction is perpendicular to the direction of bubble ejection. While uniform oriented fiber bundles composed of superfine fibers are obverse when the blowing air directs to the bubble ejection. The paper reveals that blowing air direction can be used to control morphology and structure of fibers during the spinning process.

Lightning-Like Charged Jet Cascade in Bubble Electrospinning with Ultrasonic Vibration

Lightning is a natural phenomenon caused by an atmospheric electrical discharge, and lightning strikes are of hierarchical structure. Similar phenomenon is first observed in a charged jet in the presence of a high electrostatic field, the process is widely adopted for fabrication of superfine fibers, and its mechanism of lightning-like charged jet is still unknown. Our observation reveals that a daughter jet can be ejected from the surface of a micro/nanoscale charged jet to form an initial two-stage cascade, whereby the daughter charged jet can reduce size over three orders of magnitude, while at the ultimate stage, the jets have almost same size from several nanometers to dozens of nanometers. The origin of this phenomenon might be central to nanotechnology. Here we demonstrate that an electrostatic field can accelerate a charged jet, and the surface charge repels each other. When the repelling force reaches a threshold to overcome its surface tension, one or more daughter charged jets are ejected from the surface. The daughter jets behave similarly to the initial jet, the process is iterative, creating a lightning-like multi-stage cascade. This observation opens the door to mimicking the lightning to produce two dimensional superfine fiber web with hierarchical structure.

Numerical Study on the Polymer Drawing of the Unsymmetrical Air Flow Field in Melt Blowing Process

Melt blowing is a typical nonwoven process for producing superfine fibers. In this process, the high velocity hot air jets attenuate the polymer melt into superfine fibers. Therefore, the fiber diameter is strongly affected by the air flow field. Dual slot die is one of the widely used melt blowing dies. Hot air emits from the two slots symmetrically. What will happen to the polymer drawing if the air jets are unsymmetrical? In this paper, the unsymmetrical air flow field of the dual slot die in melt blowing process is simulated numerically. The distributions of air velocity and air temperature are obtained. The polymer drawing model is then solved with the aid of the simulation results of air velocity and air temperature. The diameter and transverse displacement of the threadline along the spinline is achieved. The result shows that the threadline diameter of unsymmetrical air flow field is larger than that of the symmetrical air flow field and the threadline tends to deflect because of the unsymmetrical air jets. This paper helps to indicate the research direction for further decreasing the fiber diameter of melt blown nonwoven fabrics.