Nanofibers electrospun

Figure 4.22 (a) SEM photograph PANI/PMMA coaxial nanofibers (electrospun PMMA solution 0.18 g ml ). (b) Photograph of a gas sensor based on PANI/PMMA coaxial nanofibers. (Reprinted with permission from Sensors and Actuators B., Gas sensing properties of a composite composed of electrospun polyfmethyl methacrylate) nanofibers and in situ polymerized polyaniline by S. ji, Y. Li and M. Yang, 133, 644-649. Copyright (2008) Elsevier Ltd)... 

Figure 3.23 (a) Chemical structure of NTDA-BDSA-r-APPF (b) schematic representation of co-SPI nanofiber (c,d) TEM image of cross-sectional aligned nanofiber in the radial and axial direction, respectively (e) SEM image of aligned nanofiber electrospun on specially designed collector. Reproduced with permission from Ref [268],... 

Figure 1.3 SEM image comparing the diameter of a human hair with that of PMMA nanofibers electrospun from DMF solution. (Courtesy of RTI International.)...

Figure 1.10 (a) Scanning electron micrograph of PS nanofibers electrospun from a 22.5 wt% solution in DMF using a 0.15-mm diameter Teflon tube as the capillary tip. Scale bar is 2n,m. (b) Nanofiber diameter distribution derived from the image. (Courtesy of RTI International.)... 

Even within the concentration regime that obtains electrospinning, the quality of nanofibers electrospun can be quite variable. Koski et al. (2004), electrospinning poly(vinyl alcohol) (PVA) in aqueous solution at... 

Figure 3.10 Poly(e-caprolactone) (PCL) nanofibers electrospun from 5 wt% solution in CHCI3 at a gap distance of 7.5 cm. The applied voltages in the two panels are (a) 20 kV and (b) 25 kV. Reprinted with permission from Hsu and Shivkumar (2004a). Copyright 2004. Springer.

Figure 4.3 Scanning electron micrograph (SEM) images (same magnification) of PS nanofibers electrospun from 30% w/v solutions of (a) 1,2-dichloroethane, (b) DMF, and (c) ethyl acetate solutions at an applied potential of 20 kV and a gap distance of 10 cm, illustrating the widely different fiber diameters. Reproduced with permission from Jarusuwannapoom et al. (2005). Copyright 2005. Elsevier.

TABLE 4.3 The effect of polarity on the average diameter of PAN nanofibers electrospun from DMF solutions... 

Figure 5.15 Tensile stress-strain curves for single nanofibers electrospun under the same conditions but collected on a drum rotating at low and high speeds (strain rate 25%, 20 mm gauge length). Reprinted with permission from Inai et al. (2005a). Copyright 2005. Institute of Physics.

Annealing at a higher temperature can dramatically increase the amount of crystallinity in polymers, including nanofibers (Inai et al. 2005a). On annealing PDLA noncrystaUine PEO nanofibers electrospun from CH2CI2/DMF (1 5), at a temperature of 55°C for 24 h, two characteristic crystalline... 

Figure 9.2 Field emission environmental SEM image of PC nanofibers electrospun from chloroform, showing porosity due to phase separation. Reprinted with permission from G. M. Kim et al. (2005b). Copyright 2005. Elsevier.

At moderate strains the modulus of an isotropic fiber mat of pellathene (polyurethane) nanofibers electrospun from 7% DMF was higher than that of the bulk polymer (Pedicini and Farris 2003). Similar data were reported for PAN nanofibers (Fennessey et al. 2006). 

Pedicini and Farris (2003) used the dichroic ratio of the — NH stretching band (3320 cm ) in polyurethane nanofibers electrospun from 7% DMF to estimate the orientation function / for nanofibers. Herman s function, /, varies from/= 0 (isotropic) to/= 1 (perfect chain orientation). The value of/is related to the average angle 6 made by the oriented chain axis to that of the fiber (Fig. 9.13) ... 

Casein nanofibers electrospun Xie and Hsieh (2003) as blends with water-soluble polymers to obtain blend nanofiber and subsequently crosslinked with isocyanate. 

DMAc + LiCl A nonwoven fabric of polymer ( 4wt%) nanofibers electrospun, and... 

---