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1.
Solution blowing process is a new nanofiber fabricating method with high productivity. In the present study, nylon 6 nanofiber mats were solution blown and the effects of spinning conditions on nanofibers morphology were investigated. The fiber diameter ranged from 150 to 750 nm which was affected by solution concentration, gas pressure and solution feeding rate. The solution blown fibers were three-dimensional curly which made loose construction in bulk. The filtration performance of solution blown mats was evaluated. The tested solution blown nanofiber mats showed high filtration efficiency of 83.10 % to 93.45 % for 0.3 µm particles filtration and extremely low pressure drop of 15.37 to 30.35 Pa. The results indicate the solution blown nanofiber mats will find potential application of high efficiency and low resistance filter.  相似文献   

2.
Electrospinning is an efficient method to produce polymer fibers with a diameter range from nanometers to a few microns using an electrically driven jet. Electrospun nanofiber nonwoven fabrics can be applied into different areas with higher air volume fraction, especially applied into textile materials with good warmth retention property. In this article, the air volume fraction in nonwoven mats made of electrospun nanofibers was verified by studying fiber volume fraction in the mats. Then the relationship between fiber volume fraction and fiber diameter was derived, and the fiber volume fraction is in direct ratio to the square of fiber radius. By experimental verification, to get electrospun PAN nanofiber nonwoven mats with high air volume fraction about 99 %, it can fix the polymer concentration on 8 %. The voltage fixed on 20 kV, the tip-to-collector distance on 15 cm. The experiment is in accordance with the theory excellently.  相似文献   

3.
In this work, a series of needle-punched nonwoven filter media was prepared by using polyester fibres of three different cross-sections (circular, trilobal, and deep-groove) in accordance with a three-component augmented simplex lattice design. The experimental data of filtration efficiency and pressure drop were analyzed by means of response surface methodology. Statistical model equations were developed for filtration efficiency and pressure drop by using Design-Expert® software. The filtration efficiency and pressure drop were expressed as linear functions of proportion of fibres of different shapes. Statistical checks (ANOVA, R 2 and p-value) indicated that these models were adequate for representing the experimental data. By means of contour plots, the effect of filter constituents on filtration performance was analysed. The filter media consisting of deep-grooved fibres exhibited highest filtration efficiency but at the cost of highest pressure drop. On the other hand, the filter media consisting of circular fibres displayed lowest pressure drop but at the cost of lowest filtration efficiency. As a compromise for simultaneously achieving maximum filtration efficiency of 61.52 % and minimum pressure drop of 13.6 Pa, the optimum mixture was predicted to consist of 53.7 % deep grooved fibres and 46.3 % circular fibres. The predicted response was found in close agreement with the experimental data. This demonstrates the effectiveness of the approach reported here for achieving good predictions, while minimizing number of experiments.  相似文献   

4.
Polyimide (P84) nanofibers of 200-500 nm were deposited uniformly on needle punched aramid felt with basis weight of 260-350 g/m2 by optimized electrospinning. High temperature adhesive was then electro-sprayed on the nanofiber side deliberately to bind a thin protective layer made of temperature-resistant non-wovens. The three layer structure was afterwards enforced by hot pressing to form composite filter media. The application of the adhesive was tailored not to affect the permeability of the substrate felt while exerting adhesion strength of over 1000 kPa for the media to be suitable for flue gas dust treatment under 240 ºC. When 0.3-10 μm NaCl aerosols were used as the simulated dusts, it was found that even a small amount of P84 nanofibers could obviously elevate the filtration efficiency. The composite showed 100 % removal efficiency of particles equal and greater than 2.0 μm, and 99.5 % for particles 1.0-2.0 μm in diameter.  相似文献   

5.
Two kinds of composite filter materials were prepared by regulating the structure of melt-electrospinning polypropylene (PP) webs. The self-designed multi-nozzle melt-electrospinning device was used to produce PP webs which deposited on PP spunbonded nonwoven. Firstly, the composite filter materials with different thickness and ratios of coarse/fine fibers were prepared, and the effect of the thickness and the ratio of coarse/fine fibers on filtration properties were studied. The results showed that the filtration efficiency and pressure drop increased as thickness increased. In addition, compared with the general filters which were composed of coarse or fine fibers, the filters with coarse/fine fibers had “low pressure drop” under the similar filtration efficiency. In the case of the ratio of coarse/fine fiber about 2:2, this filter achieved optimal performance. When the thickness was 0.42 mm, its filtration efficiency for particles more than or equal to 2.0 μm could reach more than 95 %. Its pressure drop and air permeability were 18.13 Pa and 54.69 mm/s, respectively, while those of general filter were 38.67 Pa and 10.02 mm/s, respectively. After that, the composite filter materials composed of various angles of oriented webs were produced. The results showed that the filtration efficiency for particles with the size of more than or equal to 2.0 μm was higher than that of filters composed of one angle of oriented webs. In addition, the lower the orientation was, the lower the pressure drop was.  相似文献   

6.
A novel method named as high pressure air-jet atomized electrospinning was proposed to prepare nanofibers with ultrahigh production. The spinning solution with lower concentration and viscosity was cutted into micron-sized droplets by a 700 mesh filter in the front of nozzle and then was crushed and atomized into massive smaller droplets, which were drawn into nanofibers directly under the electric force and airflow force. Flow field under different air pressure was simulated to study its effect on the formation of nanofibers. The airflow showed the minimum pressure and maximum velocity at a location 2 cm away from the spray nozzle, where small droplets cutted were crushed and atomized into massive smaller droplets by the converging airflow. The velocity and distribution region of the airflow increased with increasing air pressure. It showed a smaller diameter of 150 nm and ultrahigh production of 75.6 g/h for nanofibers prepared based on this novel method at the air pressure of 0.8 MPa. The production of nanofibers almost reached thousands of times of that from conventional needle electrospinning.  相似文献   

7.
This study takes polyacrylonitrile (PAN) as a raw material for PAN-based nanofiber nonwoven prepared using electrospinning. First we construct a thermal-stable process for the fabrication of oxidized nanofiber nonwovens as the precursor. A semi-open high-temperature erect furnace is then used with steam as the activator, through carbonization and activation processes to prepare carbon nanofiber absorbents continuously. The experiment varies the production rate and activator flow rate to prepare carbon nanofiber absorbents. Experimental results show that carbon nanofiber adsorbents are primarily made up of micropores and mesopores, averaging under 20 Å. Given a production rate of 10–20 cm/min with a matching activator feed rate of 120 ml/min, the specific surface area can reach about 1000 m2/g, producing an adsorption ratio of carbon tetrachloride over 200 %.  相似文献   

8.
A poly(acrylonitrile) (PAN) nano-web was electrospun on a commercial melt-blown poly(propylene) (PP) filter medium to generate composite filter media. The performance of these media was characterized in terms of filtration efficiency and pressure drop. Quality factors calculated from these parameters were used to evaluate the overall efficacy of the filter media. Structural characterization of the composite media showed that a thin layer of nano-web could improve the overall performance by increasing filtration efficiency without significant increase of pressure drop.  相似文献   

9.
Electrospinning is a simple and cost-effective method to prepare fiber with nanometer scale. More importantly, 3D flexible nanofiber yarns that fabricated by electrospinning have shown excellent application prospects in smart textiles, wearable sensors, energy storage devices, tissue engineering, and so on. However, current methods for preparing electrospinning nanofiber yarns had some limitations, including low yarn yield and poor yarn structure. In this paper, a stepped airflow-assisted electrospinning method was designed to prepare continuously twisted nanofiber yarn through introducing stepped airflow into traditional electrospinning system. The stepped airflow could not only help to improve nanofiber yield, but also good for controlling the formed nanofibers to be deposited in a small area. In addition, the experimental methods of single factor variables were used to study the effects of stepped airflow pressure, applied voltage, spinning distance, solution flow rate, air pumping volume and friction roller speed on nanofiber yarn yield, nanofiber diameter, yarn twist and mechanical property. The results showed that prepared nanofiber yarns exhibited perfect morphologies and the yield of nanofiber yarn could reach to a maximum of 4.207 g/h. The breaking strength and elongation at break of the prepared yarn could reach to 23.52 MPa and 30.61 %, respectively.  相似文献   

10.
Gallium arsenide (GaAs) does have superior electronic properties compared with silicon. For instant, it has a higher saturated electron velocity and higher electron mobility. Weak mechanical properties and high production cost are the main drawbacks of this interesting semiconductor. In this study, we are introducing production of GaAs nanofibers by electrospinning methodology as a very low cost and yielding distinct product technique. In general, nano-fibrous shape is strongly improving the physical properties due to the high surface area to volume ratio of this nanostructure. The mechanical and environmental properties of the GaAs compound have been modified since GaAs nanofibers have been produced as a core inside a poly(vinyl alcohol) (PVA) shell. GaAs/PVA nanofibers were prepared by electrospinning of gallium nitrate/PVA solution in presence of arsenic vapor. The whole process was carried out in a closed hood equipped with nitrogen environment. FT-IR, XPS, TGA and UV-Vis spectroscopy analyses were utilized to confirm formation of GaAs compound. Transmission electron microscope (TEM) analysis has revealed that the synthesized GaAs compound is crystalline and does have nano-fibrous shape as a core inside PVA nanofibers. To precisely recommend the prepared GaAs nanofiber mats to be utilized in different applications, we have measured the electric conductivity and the band gap energies of the prepared nanofiber mats. Overall, the obtained results affirmed that the proposed strategy successfully remedied the drawbacks of the reported GaAs structures and did not affect the main physical properties of this important semiconductor.  相似文献   

11.
The fibrous porous materials stand out as a unique class of porous media. The air permeability of these media is very important for a wide variety of medical and technical applications. It is observed that the air permeability of these media is different at different locations owing to the nonuniformity in fibre packing density. This observation is taken into consideration while developing an analytical model of air permeability of nonuniform fibrous porous media. This model is reported in this article and demonstrated with the help of practical examples of real nonwoven fibrous porous materials. The theoretical results are found to be in satisfactory agreement with the experimental ones.  相似文献   

12.
In this study, electrospun wool keratose (WK)/silk fibroin (SF) blend nanofiber was prepared and evaluated as a heavy metal ion adsorbent which can be used in water purification field. The WK, which was a soluble fraction of oxidized wool keratin fiber, was blended with SF in formic acid. The electrospinnability was greatly improved with an increase of SF content. The structure and properties of WK/SF blend nanofibers were investigated by SEM, FTIR, DMTA and tensile test. Among various WK/SF blend ratios, 50/50 blend nanofiber showed an excellent mechanical property. It might be due to some physical interaction between SF and WK molecules although FTIR result did not show any evidence of molecular miscibility. As a result of metal ion adsorption test, WK/SF blend nanofiber mats exhibited high Cu2+ adsorption capacity compared with ordinary wool sliver at pH 8.5. It might be due to large specific surface area of nanofiber mat as well as numerous functional groups of WK. Consequently, the WK/SF blend nanofiber mats can be a promising candidate as metal ion adsorption filter.  相似文献   

13.
The permeability defined by Darcy’s law indicates the degree of ability that a fluid can flow through nonwoven media under a differential pressure in laminar flow. The permeability generally indicates the specific permeability or absolute permeability. On the other hand, if the fluid is water, the permeability indicates the hydraulic conductivity or permeability coefficient. The permeability is one of the important properties for nonwoven media and a prediction of the permeability acts as a bridge between the manufacturing technology and performance requirements. Because capillary channel theory aims to make the flow of fluid easier and more understandable, many models are based on capillary channel theory. On the other hand, the theory has a limitation in that it is unsuitable for high porosity media. In this study, a very thin downstream layer, which was suggested by Lifshutz [9], was introduced to derive a prediction model of hydraulic permeability. Needle-punched and spunbonded nonwoven fabrics with various basis weights were used in the cross-plain water permeability test. From this ‘thin layer’ model, reasonable agreement between the predicted and experimental results was obtained.  相似文献   

14.
The use of nonwoven textile substrates for filtration and absorption purposes is generalized due to the high surface area they can provide. Many of these applications require good wetting properties to increase efficiency. In this work, low pressure plasma treatment with a CH4-O2 mixture gas has been used to increase surface wettability and subsequent absorption properties on nonwoven polypropylene substrates. CH4 plasma treatment leads to a plasma polymerization process which results in hydrophobic surface finishing, but in combination with O2, it is possible to form a functionalized plasmapolymerized layer thus improving wetting properties. Changes in wetting properties have been studied by contact angle measurements showing that optimum wetting properties are obtained with exposure times to plasma treatment of about 10 min, and no significant changes are obtained for longer exposure times. Absorption efficiency has been followed by determining three different parameters by the guidelines of the UNE-EN-ISO 9073-6 standard: wetting time, liquid absorption capacity (LAC) and liquid propagation rate or absorption speed. All these properties are remarkably improved as the exposure time to CH4-O2 plasma increases; this improvement is remarkably high for relatively short exposure times (5?C10 min) and no significant changes are obtained for long exposure times so that, it is possible to conclude that previous plasma treatment with exposure times in the 5?C10 min range is an efficient method to improve overall absorption properties of nonwoven polypropylene substrates.  相似文献   

15.
This paper focused on using response surface methodology (RSM) and artificial neural network (ANN) to analyze polyurethane (PU) nanofibers morphology synthesized by electrospinning. The process was characterized in detail by using experimental design to determine the parameters that may affect the nanofibers morphology such as polymer concentration, a tip to collector distance and applied voltage. It was concluded that solution concentration plays an important role (relative importance of 79.85 %) against nanofibers diameter and its standard deviation. Based on the results, applied voltage has a different effect on the nanofiber diameter at low and high solution concentrations. Moreover, the tip to collector distance parameter has no significant impact on the average nanofiber diameter. The finest PU nanofiber (201 nm) was obtained from experimental under conditions of: 9 w/v% polymer concentrations, 12 cm tip to collector distance and 16 kV applied voltage. The results show a very good agreement between the experimental and modeled data. It was demonstrated that both models (specially, in case of neural network) are excellent for predicting diameter of PU nanofibers. Furthermore, numerical optimization has been performed by considering desirability function to access the region in design space that introduces minimum average diameter.  相似文献   

16.
The core-sheath nanofibers consisting of polyurethane (PU) core and PU composites sheath with multi-walled carbon nanotubes (MWNTs) were prepared by electrospinning. At low MWNT concentration, MWNTs appeared highly aligned along the fiber axis with some curving in nanotubes, whereas in case of high concentration, some aggregation of MWNTs appeared due to difficulty in full dispersion of nanotubes. In comparison of the single component nanofiber webs, the core-sheath nanofiber webs showed much better mechanical properties of modulus and breaking stress, including an exceptional elongation-at-break. It indicates that the CNT-incorporated core-sheath structure is very effective for enhancing the mechanical properties of nanofiber webs. In addition, the core-sheath nanofibers demonstrated the fast shape recovery, compared with one component fibers of pure shape memory PU and PU/MWNTs, which provides the possibility of fabricating more sensitive intelligent materials.  相似文献   

17.
A method is presented to immobilize Cu-BTC metal-organic framework (MOF-199) particles by enmeshing them in nonwoven polyacrylonitrile (PAN) nanofibers creating a fibrous membrane with the potential ability to remove chemical warfare agents or pesticides from solution. These membranes were shown to effectively adsorb methyl parathion, an organophosphate pesticide. Based on solubility theory and experimental results, partitioning was determined to be the main mechanism of removal. After 2 hours, the PAN/MOF-199 membranes removed 88 % more methyl parathion than the unmodified PAN membranes and 62 % as much as the MOF-199 crystal powder. Since the MOF particles were enmeshed in the PAN fiber mats, the MOF particles were in a workable and flexible substrate. Potential applications of these functionalized fibrous membranes include protective clothing for agricultural workers or military personnel as well as filtration media.  相似文献   

18.
In this study, two kinds of polyacrylonitrile (PAN) (carbon fiber grade PAN and oxidized fiber grade PAN) are used as the raw materials for a PAN-based nanofiber nonwoven that is prepared using electrospinning. A high-temperature erect furnace is then used, which uses oxidization processes to prepare oxidized nanofiber nonwovens in a continuous manufacturing process. The parameters used for the oxidation process are oxidation temperatures of 150, 200, 250, 275, 300 and 300 °C, which correspond to a production rate of 3, 5 and 10 cm/min at 5-cN tension. The variation in the yield rate, the breaking strength and the shrinkage of the oxidized PAN based electrospun nonwovens are examined in this study. The results demonstrate that the limit oxygen index (LOI) and aromatization index (AI) increase as the production rate decreases. Under the optimum oxidation conditions, higher quality oxidized electrospun nonwovens are produced using carbon fiber grade PAN with AI of 61 % and LOI of 42 %.  相似文献   

19.
The formation of a symmetric electrospinning triangle zone (E-triangle) via a technique based on using two oppositely charged nozzles is described for fabricating continuous twisted nanofiber yarn of polyamide (Nylon 66). This study shows how changing the dimensions and geometry of the E-triangle influences the distribution of nanofiber tension and diameter in this zone, and consequently how it affects the nanofiber yarn strength. The twist effect on the E-triangle geometry was investigated by changing the rotational speed of the twister plate of values of 96, 160, 224 and 288 rpm. The results showed that by increasing the twist rate, the apex angle of the E-triangle increased, whereas the height and width of the Etriangle decreased. An energy method was adopted to study the distribution of tension on nanofibers in the E-triangle. Considering a constant spinning tension, it was observed that the gradient of the nanofiber tension curve was steeper and the extreme values of tension on nanofibers were increased by increasing the twist rate. Furthermore, the mean diameter reduction of nanofibers confirmed these results. It is concluded that mechanical properties of nanofiber yarn have been considerably improved by increasing the twist rate and changing the shape of the E-triangle.  相似文献   

20.
Herein we report successful synthesis of silk fibroin (SF) three dimensional scaffolds (SF 3D-scaffold) from SF sponge and SF nanofibers. Both the nanofibers and sponge were prepared from Bombyx mori fibroin. The SF 3D-scaffold was prepared by electrospinning the fibroin nanofibers over the sponge. Surface morphology was determined by scanning electron microscopy (SEM), while nanofiber diameter and pore size were measured using imageJ software. Effect of spinning time on the pore size and cell adhesion was determined. Average diameter of the SF nanofibers was measured to be 320 nm and pore size was found to reduce with increasing spinning time, such that, for 1 h spinning time pore size was 231 µm and the same for 3.5 h was 4.1 µm. However, the number of pores increased with spinning time. The results confirmed adhesion of MC3T3-E1 cells on the SF sponge, SF nanofibers and SF three dimensional scaffolds. Higher cell adhesion was found on the three dimensional scaffold in comparison to the nanofibers and sponge, possibly due to highly porous structure with very small and numerous pores in the resultant composite; hence more cell adhesion sites. The cell adhesion result confirmed biocompatibility of the SF 3D-scaffold and hence its suitability for applications in tissue engineering.  相似文献   

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