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Isotactic polystyrene was electrospun into ultrafine fibers from the chloroform or tetrahydrofuran solutions. Tubular or ribbon-like fibers with many small pores were obtained from the chloroform solution. Densely stacked lamellae were formed by annealing them. On the other hand, fibers with many small dents on the skin layer were obtained from the tetrahydrofuran solution. The skin layer changed...
Polyvinyl alcohol (PVA) nanofibers, PVA/Type I Collagen (Col) and their composites with hydroxyapatite nanoparticles (nano-HAp) were prepared by electrospinning techniques. The composite nanofibrous membranes were subjected to detailed analysis. Morphological investigations show that the generated nanofibers (NFs) have uniform morphology with an average diameter of ∼160 nm for pure PVA, ∼176 nm for...
The selection of a desirable solvent or solvent system as the carrier of a particular polymer is fundamental for the optimisation of electrospinning. Solvent selection is pivotal in determining the critical minimum solution concentration to allow the transition from electrospraying to electrospinning, thereby significantly affecting solution spinnability and the morphology of the electrospun fibres...
Nanofibers of highly sulfonated (IEC ∼4.5 meq/g) polystyrene (SPS) were successfully electrospun. To accomplish this, the process of electrospinning this difficult-to-spin material was studied in detail. Fiber quality was optimized by manipulating the process and solution variables to fabricate continuous bead-free fibers. Bead-free fibers (average diameter 260nm) were electrospun from 25wt% SPS (500kDa)...
In this study, the aliphatic polyketone (PK) fibrous membrane was successfully prepared from the solution by electrospinning process at room temperature. As solvents for PK polymer, the mixed solvents of trifluoroacetic acid (TFA) and dichloromethane (MC) were used. Electrospun PK fibrous membrane was characterized by scanning electron microscope (SEM), wide angle X-ray diffraction (WAXD), differential...
A systematic orientation analysis of individual electrospun polyethylene (PE) nanofibers was performed by transmission electron microscopy (TEM). PE nanofibers with a wide diameter distribution, ranging from 150 nm to several micrometers, and a variety of morphologies, including cylindrical, beaded- and ribbon-like fibers, were produced by the high-temperature solution electrospinning. In each fiber,...
Graphitic carbon nanofibers (GCNFs) with diameters of approximately 300 nm were developed using bundles of aligned electrospun polyacrylonitrile (PAN) nanofibers containing phosphoric acid (PA) as the innovative precursors through thermal treatments of stabilization, carbonization, and graphitization. The morphological, structural, and mechanical properties of GCNFs were systematically characterized...
Pure poly(3-hydroxybutyrate-co-3-hydroxyvalerate) (PHBV) and zinc oxide (ZnO)/PHBV composite nanofibers were fabricated by an electrospinning method. ZnO nanoparticles (NPs) with a diameter of about 10–20 nm were doped in the PHBV fibers and no dispersion agent was utilized. Both pure PHBV and composite electrospun fibers were smooth and uniform. ZnO NPs did not affect the basic crystalline structure...
The interlaminar toughening of a carbon-fibre reinforced composite by incorporation of electrospun polyvinylidene fluoride (PVDF) nanofibrous membranes was explored in this work. The electrospinning process of low and high molecular weight PVDF was optimised to form nanofibres free of defects with diameters averaging several hundred nanometres. The nanofibres were electrospun directly onto commercial...
Stabilization of the jet is necessary for the successful fabrication of continuous fibers from solutions via electrospinning. Although intensively studied over the past decade, the mechanisms underlying jet stabilization are still not precisely understood. The traditional explanation for jet stabilization emphasizes the role of the elastic response of the polymer coil in creating a sufficiently high...
PVA nanofibers electrospun from solutions with relatively low polymer concentrations (below 8 wt%) tend to be no longer smooth, but display barbs which occur regularly spaced along the nanofiber length. Such structures are of interest for a number of technical applications, since they affect the fiber packing, pore sizes and the internal surfaces in the nanofiber nonwovens. This paper reports both,...
Partially crystalline bisphenol A polycarbonate (BPAPC) nanofibers were successfully fabricated using a combination of a centrifugal field (1800rpm) and an electrostatic field (25kV). The BPAPC solution properties are key factors for adequately electrospinning the partially crystalline BPAPC nanofibers. The correlation times (τ c ) of methyl (τ c =9.3 ns) and of benzene-ring (τ ...
The molecular weight distribution (MWD), rheology and electrospinning of a series of wheat gluten (WG) mixtures with poly(vinyl alcohol) (PVA), dithiothreitol (DTT), and thiolated poly(vinyl alcohol) (TPVA) in water/1-propanol (1/1) were investigated by size-exclusion chromatography, steady-shear viscosity measurements and scanning electron microscopy. Thiolated additives reduce disulfide bonds between...
Ordinarily, the electrospinning process generates one-dimensional fibers which assemble into non-woven membrane structures due to instabilities in the fluid jet. In this paper, an electrospinning procedure is developed that utilizes patterned collectors to produce aligned membranes with designed topological structures. The template-assisted electrospinning approach is demonstrated using polycaprolactone...
Poly(lactide-co-glycolide) (PLGA) has been widely explored as scaffolds in tissue engineering. However, its hydrophobicity can adversely affect events such as protein adsorption and downstream cell adhesion in tissue engineering applications. Although surface modification techniques (high energy radiation/chemical treatment) to modify the hydrophobicity of PLGA can be useful at the macroscopic scale,...
Cellulose nitrate-acetate mixed esters (CNA) were synthesized by nitration of cellulose diacetate, using HNO 3 /H 2 SO 4 as nitration agent. The CNA structures were confirmed and analyzed by IR and 1 H NMR. A decrease in molecular weight and an increase in nitrate group content were observed with increasing H 2 SO 4 ratio and reaction time. The highest...
The concept of a gas-assisted polymer melt electrospinning process is presented. This technique allows for reduced quenching of the melt jet in the spinning region, and thus increasing the jet attenuation rate and resulting in production of sub-micron scale fibers. A comprehensive melt electrospinning model was used to analyze the effects of the heated air stream on the polymer jet. It was found that...
Novel core-sheath nanofibers, composed of polyacrylonitrile (PAN) core and polypyrrole (PPy) sheath with clear boundary between them, were fabricated by electrospinning PAN/FeCl 3 ·6H 2 O bicomponent nanofibers and the subsequent surface-initiated polymerization in a pyrrole-containing solution. By adjusting the concentration of FeCl 3 ·6H 2 O, the surface morphology...
We report here the formation and structural characterization of optically responsive, highly birefringent electrospun nematic liquid crystal (LC) microfibers. The LC microfibers are electrospun from a solution of polylactic acid (PLA) and low molecular weight 4-pentyl-4 ’ -cyanobiphenyl (5CB) in chloroform/acetone solvent. In the electrospinning process, the low molecular weight 5CB phase-separates...
In electrospinning, electrostatic interaction between charged fibers and the collection substrate can result in poor and non-uniform coverage, particularly when electrically insulating substrates are used, because they are prone to surface charge accumulation. Charged electrospun Nylon-4,6 nanofiber coatings were deposited onto substrates of varying size, conductivity and morphology. The density and...
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