Nanofibers diameters

Deitzel et al. (2001a) attributed the presence of smaUer-diameter nanofibers in the bimodal distribution of fibers from electrospinning PEO in water solutions to splaying of the jet. 

Flow through fibrous media was modeled considering the nanofiber diameter, nanofiber arrangement, and porosity of the mat. The permeability factor for the nanoliber mat was modified to take into account the effect of sandwich structure as per the resistances-in-series law and converted to permeation in cc-mm/m day for comparison with the experimental values. The presence of GO was not taken into account here. 

The flexibility of fibers is affected by both the chemical and physical stmc-tures. For example, most polymer fibers are flexible since they are made of flexible chains. However, the flexibility is reduced with increase in the orientation of polymer chains. The flexibility of fibers can be increased by introducing the crimp stmcture along the longitudinal direction or changing the circular cross-section to an oval one. Another important and effective method to increase the fiber flexibility is by reducing the fiber diameter. Nanofibers are very flexible due to their nanoscale diameters. 

As can be seen from Figure 2.1, cobalt was deposited on the carbon nanomaterials quite homogeneously. Hence, the cobalt particle sizes of the three catalyst types vary only little. The Co/nanofiber materials exhibit cobalt particle diameters of roughly 10 nm. In case of the nanotubes, particle sizes ranging from 5 to 7 nm were observed. 

A) is much smaller than the lamellar length of ordinary PE crystals ( 100A), thus the PE chains are prevented from folding. In this manner, extended-chain crystalline nanofibers of linear polyethylene with an ultrahigh molecular weight (6,200,000) and a diameter of 30 to 50 nm are formed. 

The perfection of this nanocoating process following free shapes in three dimensions is nicely illustrated by the coating of nanowires. Uniform carbonaceous nanofibers of only some nanometers in diameter with high aspect ratio could be... 

In this chapter, we reviewed the structure-controlled syntheses of CNFs in an attempt to offer better catalyst supports for fuel cell applications. Also, selected carbon nanofibers are used as supports for anode metal catalysts in DMFCs. The catalytic activity and the efficiency of transferring protons to ion-exchange membranes have been examined in half cells and single cells. The effects of the fiber diameter, graphene alignment and porosity on the activity of the CNF-supported catalysts have been examined in detail. 

The nanofibers formed by PAs are microns long and have a uniform diameter of approximately 6-8 nm, depending on the length of the PA molecule. Self-assembly of the nanofibers can be controlled by pH adjustment and/or addition of divalent... 

Sone and Samuel (2004) continued the studies of mineralization on PA nanofibers by utilizing the same PA described above to nucleate and grow CdS nanocrystals. In this case, the negatively charged phosphate and carboxylate groups bind to Cd, and CdS was formed after diffusion of H2S gas. A low Cd to PA ratio led to the formation of CdS nanocrystals that were 3-5 nm in diameter. An intermediate ratio of... 

Electrospinning is a method allowing creation of polymer fibers with diameters in the range between a few tens of nanometers to a few micrometers, starting from a solution of preformed polymer. MIP nanoparticles have been included into nanofibers by electrospinning [126, 127], In another case, the nanofibers were directly produced by electrospinning and polymerizing an MIP-precursor solution [128]. Such MIP fibers can then be used, for example, for the preparation of affinity separation materials [129] or as affinity layers in biosensors [127, 130]. 

Five years after the discovery of fullerenes, Iijima reported in 19911 a novel form of organized carbon which consists of hollow cylindrical structures, a few nanometers in diameter and some micrometers long. Although hollow carbon nanofibers had been prepared for several decades, their walls had never been resolved by High-Resolution Transmission Electron Microscopy (HRTEM). These HRTEM images allowed Iijima to conclude that the walls of the so-called multi-walled carbon nanotubes (MWCNTs) are made up of several concentric cylinders, each being formed by a graphene sheet rolled... 

---