Wetting behaviors of fluoroterpolymer fiber films

Various aspects of electrospun fibers prepared from terpolymer of tetrafluoroethylene (TFE), hexafluoropropylene (HFP), and vinylidene fluoride (VDF) (THV)/acetone solutions at two applied voltages, THV/acetone solutions having Texas montmorillonite with two ratios, and THV/ethyl acetate solutions using two needle sizes are described. Fibers from THV/acetone and THV/ethyl acetate solutions showed shallow indentations and pores, respectively. The clay, functioning as electrospinning agent, did not influence the fiber morphology, but yielded narrower fiber diameter distribution and the thinnest fibers. Heterogeneous fiber diameter distribution and increase in the fiber diameters were observed by lowering the voltage for fibers of THV/acetone solutions. Fibers from THV/ethyl acetate solutions had the largest diameter and the broadest diameter distribution. Electrospun THV fibers having both hydrophobic characteristics with nearly 140° water contact angles and oleophilic properties with oil contact angles less than 45° might have applications in areas such as water/oil separation.

Processing of polycaprolactone and hydroxyapatite to fabricate graded electrospun composites for tendon-bone interface regeneration

The process of electrospinning is utilized with different approaches including conventional electrospinning, extrusion electrospinning, and electroblowing to form nanofibrous meshes and composites. Here, we report on the quality and properties of spatially graded polycaprolactone (PCL) and nano-hydroxyapatite (nHA) composite meshes fabricated with multiple-spinneret electrospinning. The composite meshes were characterized in terms of the amount of spatially allocated nHA concentration across the mesh, fiber diameter, porosity, pore size, and hydrophilicity of meshes. Results show that linearly and continuously varying nHA concentration distribution, i.e. graded structure, can be accomplished across the mesh thickness using multiple-spinneret electrospinning, which is in accordance with the change of mineral concentration observed in native tendon-bone interface. Furthermore, incorporation of nanoparticles into nanofibers led to increased fiber diameter as depicted by a shift in fiber diameter distribution, a significant increase in mean fiber diameter from 361±9 nm to 459±21 nm, and an increase in contact angle from 120.01±2.77° to 115.24±1.17°. These findings suggest that the composite meshes formed in this study could serve as model systems to be used as scaffolds in tendon-bone tissue engineering application in particular, and for other tissue-tissue interfaces in a broader context.

Synthesis of Electrospun Nanofibers Membrane and Its Optimization for Aerosol Filter Application

Nanofibers membranes were synthesized using electrospinning method for air filtration application. Polyacrylonitrile (PAN) with three different concentrations as the polymeric matrix of the nanofibers membrane is used. In the aerosol filtration, the pressure drop is one of the most important parameters, which is determined by the membrane characteristics. One of the parameters that influence the characteristics of membrane is concentration of polymer solution, in which it will determine the diameter of fiber. In this study, the relation between the PAN concentration and the pressure drop in air filtration test was examined. Three different concentrations of PAN solution (6, 9, and 12 wt.%) were employed under the same process parameters of electrospinning. The fiber diameter distribution of each membrane was measured from its scanning electron microscope (SEM) image. The three concentrations resulted in significant different effect to the pressure drop that proved the existing correlation between the polymer concentration and the air pressure drop.

Synthesis of Electrospun Nanofibers Membrane and Its Optimization for Aerosol Filter Application

Nanofibers membranes were synthesized using electrospinning method for air filtration application. Polyacrylonitrile (PAN) with three different concentrations as the polymeric matrix of the nanofibers membrane is used. In the aerosol filtration, the pressure drop is one of the most important parameters, which is determined by the membrane characteristics. One of the parameters that influence the characteristics of membrane is concentration of polymer solution, in which it will determine the diameter of fiber. In this study, the relation between the PAN concentration and the pressure drop in air filtration test was examined. Three different concentrations of PAN solution (6, 9, and 12 wt.%) were employed under the same process parameters of electrospinning. The fiber diameter distribution of each membrane was measured from its scanning electron microscope (SEM) image. The three concentrations resulted in significant different effect to the pressure drop that proved the existing correlation between the polymer concentration and the air pressure drop.

Fabrication of Aligned PAN Nanofiber by Electrospinning with Parallel Electrode

Electrospinning has emerged as a very attractive approach to the fabrication of nanofibers. In electrospinning process, the ability to control the alignment and arrangement of fibers is critical to achieve the designed functions. In this paper, we had successfully fabricated highly aligned PAN nanofibers by the method of parallel electrode electrospinning. The study revealed the optimum weight ratio of PAN polymer solution for aligned nanofibers was 8%-12%. Results show that the increasing of weight ratio of polymer solution can enhance the parallelism and uniformity of electrospun fiber diameter distribution.

A Geometry Method for Calculating the Fiber Diameter Reduction in Melt Blowing

Melt blowing is one of the important methods for producing ultrafine fibers. The production of melt blowing is the nonwoven. Fiber diameter has crucial effect on the property of the nonwovens. In the melt-blowing process, many achievements have been published on the fiber diameter distribution along the spinning line. Note that all the results were obtained by methods of mechanical analysis, online measurements through high-speed photography and offline measurements from the production of nonwoven. In this study, a new method for calculating the fiber diameter distribution along the spinning line near the die face was revealed. This method was based on the geometry of the fiber path in the melt-blowing process. The fiber diameter reduction was calculated by this method and then compared with the experimental results obtained by other researchers. The results show that the proposed method is feasible.

The Effect of Flow Rate on Morphology and Deposition Area of Electrospun Nylon 6 Nanofiber

Electrospinning is a process that produces continuous polymer fibers with diameters of a nanometric scale. Nylon 6 in formic acid was electrospun to obtain the nanofibers. Fibers with different diameters were obtained using flow rates of 0.1, 0.5, 1 and 1.5 mL/hr, 20 wt% solution concentration, with an applied voltage of 20 kV and 15 cm spinning distance. Flow rate influenced the fiber diameter distribution, droplet size and its initiating shape at the capillary tip, the trajectory of the jet, maintenance of Taylor cone, areal density and nanofiber morphology. The morphology of the electrospun nanofibers was analyzed by using the scanning electron microscope (SEM). The effect of flow rate on the deposition area was also investigated for better control of the process. It was observed that a stabilized Taylor cone, small average droplet size, narrowest fiber diameter distribution, more stability in the originating jet, and uniform morphology of nanofiber is obtained at a flow rate of 0.5 mL/hr.