Average fiber diameter

Preferably, the lithium ion battery separators range in average fiber diameter from 1-3 p, and in basis weight from 10-20 g m-2 The average fiber diameter and basis weight are substantially the same before and after the pressing. The lithium ion battery separator desirably has a porosity of 40 to 50%, and a thickness of 20-45 p. A lithium ion battery separator with this porosity value provides a low internal resistance and does not pass electrode substances to prevent short circuits. The thickness in the above range is suitable for the separator to be applied to small sized lithium ion batteries (21). 

Figure 10. Main effect plots of applied voltage (b) on average fiber diameter [55].

At 8% concentration less than 30 nm diameter fibers were formed with beads (drops of polymer over the woven mesh) and they were not uniform and were branched off (Figure 23). At 10% eoneentration with 5 em spinning distanee and 2, 3 and 4 kV/em eleetrie fields, drops were formed instead of fibers. Continuous fibers were obtained above 12% regardless of eleetrie field and distanee (Figures 22 and 23). At 19.5%, the average fiber diameter was much larger than that of fibers spun at lower eoneentrations. In the short distanee as well as low concentration (10%), the solution reaehes the eolleetion plate before the solvent fully evaporates. This explains the formation of droplets and beads at the low eoneentration and distanee. Fewer beads were observed in electrospun fibers at higher concentration. 

The main problem with direct measurement is that fiber diameter may not be uniform along the length. An indirect method that gives an average fiber diameter is to weigh a known length of fiber and use the following simple relationship ... 

Demir et al. prepared polyurethane urea copolymer solution in DMF and observed that the average fiber diameter (AFD) increases with the solution concentration as given by AFD = (Conc.)3. A trimodal distribution of the fiber diameter has been observed with fiber diameter varying from 7 nm to 1.5 pm (Demir et al. 2002). 

Because the fiber diameters are usually not all equal and the fibers are arranged in a more or less random fashion, i)n should be inteipreted a,s an effective fiber efficiency that cun be calculated from (3.44) and ba.sedon an average diameter, r7, usually the arithmetic average. In an experimental deiermination of t/fj. the practice is to measure N and /V2, the inlet and outlet concentration of a nionodispcrse aerosol passed through the filter. The average fiber diameter, d, can be determined by microscopic examination. 

A widely cited example of a long cellulose fiber is hemp. Hemp has specific gravity of 1.5 g/cm, cellulose content about 80%, and lignin content only 4%. Average fiber diameters for long cellulose fibers are typically from 20 (hemp) to 28 me (coir). 

The blend morphology was characterized by dissolving the PEBA matrix, followed by gravimetric and microscopic analysis of the LCP phase. As expected, the average fiber diameter decreased as a function of DR °. It was noted that only relatively large drops were deformed into fibers, leaving nearly 50% of LCP in the form of small dispersed nodules. The fiber content as a function of DR followed a trend parallel to that of the mechanical properties. Longitudinal and trans-... 

Figure 17.7 (A) Cyclic voltammogram of catechol on a platinum electrode. (B) Effect of poly(aniline-co-o-aminophenol) fiber diameter on the electrochemical oxidation of catechol, at a scan rate of 60 mV Average fiber diameter ( ) 70 nm, (2) 90 nm, (3) 100 nm, (4) 107 nm, in a solution consisting of 5 mM catechol and 0.3 M Na2S04 with pH 5.0. (Reprinted with permission from Electrochimica Acta, Poly(aniline-co-o-aminophenol) nanostructured network Electrochemical controllable synthesis and electrocatalysis byShaolin Mu, 51, 17, 3434-3440. Copyright (2006) Elsevier Ltd)...

S. Sternberg, D.R. Lynn, Methods for Correlating Average Fiber Diameter with Performance in Complex Filtration Media, US... 

Average fiber diameter Central composite design Contact angle Dimethylformamide Nanofibers Polyacrylonitrile... 

At 2.7, polymer chain entanglements probability increases and the average fiber diameter goes above the micrometer range. 

The effect of humidity and temperature on the nanofibers of cellulose acetate and PVP was also investigated. It was found that for PVP, increased humidity resulted in a decrease in the average fiber diameter, while for cellulose acetate fiber diameter increased due to the chemical nature of the polymer. However, the dependence of the diameter on temperature was not linear for both polymers, since for lower temperatures, 10°C and 20°C, initially there was an increase in diameter. An increase in temperature to 30°C resulted in a decrease in diameter. 

By increasing the concentration of PPy (0%-30%) in the composite, the average fiber diameters reduced from 239 37 nm to 191 45 nm, and the tensile modulus increased from 7.9 1.6 MPa to 50.3 3.3 MPa. Nanofibers of PA6 with different amounts of PANI doped with p-TSA were obtained by Silva et al. ... 

The average fiber diameters decreased with increasing PPy content and the electrospinnability of the solution changed as a result of the interactions between the components in the structure (Fig. 8.16). Due to the strong interaction between PU and PPy, the spinnability of the composite solution was very sensitive to the amount of Py. ... 

Mit-uppatham, C., Nithitanakul, M. and Supaphol, P. 2004. Ultrafine eiectrospun polyamide-6 fibers Effect of solution conditions on morphology and average fiber diameter. 4facromo7 emj hj j 205 2327 3. ... 

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