Nano-fibres

The reactants were ultrasonically dispersed in ethylendiamine, then transferred to a Teflon-lined autoclave and gradually heated up to 160°C. The products were filtered out, washed with absolute alcohol, normal HC1 solution and water and finally dried in vacuum. In the product nano-fibres and near single-crystal whiskers were obtained. 

Protein-based nano-fibrils have been found to be very efficient gelling agents, insofar as a protein gel can be formed even at very low protein concentrations (e.g., 0.07 wt%). Applying an external shear flow can further increase the gel-forming ability of these protein nano-fibres due to their preferred orientation along the direction of the flow. The robustness of the fibres towards dilution and other physical treatments is con-... 

In contrast, the whey proteins are relatively small globular proteins. a-Lactalbumin represents about 20 % of the protein content of bovine whey (3.5 % of total bovine milk protein), and it is the principal protein in human milk (Brew and Grobler, 1992). Nanotube assembly has been discovered in some solutions containing a hydrolysed derivative of this protein. And it appears that the a-lactalbumin nanotube is unique in the sense that it is the only artificial nanotube that has so far been made from a food protein (Graveland-Bikker et al., 2004 Graveland-Bikker and de Kruif, 2006). As for p-lactoglobulin, it has the capacity under certain specific conditions to form nano-fibres in aqueous media (as can various other globular food proteins, such as ovalbumin, soy proteins, and bovine serum albumin) (van der Linden, 2006 Nicolai, 2007). 

Van der Linden and Sagis (2001) have suggested that, once a critical concentration for gel formation is known, one can predict, for example, the dependence of the gel elasticity on the concentration of protein. The minimum gelation concentration may be expressed in terms of the basic fibre characteristics like the stiffness and also as a function of salt concentration (Veerman, 2004 Sagis et al., 2004). It is pointed out by van der Linden (2006) that there are two important factors which allow the manipulation of this minimum gelation concentration to an extremely low value. The first factor is that the nano-fibre should be robust against dilution. And the second is that the fibre should robust also with respect to other treatments, especially the adjustment of the pH. It would appear that each of these conditions is satisfied. 

Silica and Carbon Nano Fibre Modifed Systems... 

The SEM picture in Figure 7 shows a cut surface from a PDMS modified with silica nano fibers. The picture shows two fibres protruding from the surface and two holes resulting from fibres being pulled free from the material shown. Clearly this is indicative of a weak interface between the PDMS matrix and silica nano fibers. It should be noted that the production process for the silica nano fibre results in a significant amount of small particulate material. However, the stress strain response obtained from the PDMS systems formulated with the nano fibre shows some interesting trends. 

Stress strain curves for silica nano fibre, CNF and systems formulated with more refined single and multi walled nano tubes are shown in Figure 12. The further simplification of the stress strain response over the PDMS formulated with fumed silica is apparent. There is no Mullins effect, in any of the tubular carbon modified systems, they all have a non complex modulas and a highly linear stress strain response. 

Figure 12. Stress strain curves for PDMS modified with 5% silica nano fibre, CNF and with more refined single and multi walled nano fiber.

Zeugolis DI et al (2008) Electro-spinning of pure collagen nano-fibres - Just an expensive way to make gelatin Biomaterials 29(15) 2293-2305... 

Ignatova M et al (2006) Electrospun nano-fibre mats with antibacterial properties from quatemised chitosan and poly(vinyl alcohol). Carbohydr Res 341(12) 2098-2107... 

Fig. 1.23 Transmission electron micrographs of the banana nano fibres [87]...

Cherian et al. [119] also extracted cellulose nanofibres from pineapple leaf fibres using acid-coupled steam treatment. The strucmral and physicochemical properties of the pineapple leaf fibres were studied by environmental scanning electron microscopy (ESEM), AFM and TEM and X-ray diffi action (XRD) techniques. The acid-coupled steam explosion process resulted in the isolation of PALF nanofibres having a diameter range of 5-60 nm. Figure 1.24a and b shows the AFM and TEM images of nano fibres obtained from pineapple leaf fibres. AFM and TEM support the evidence for the isolation of individual nanofibres from PALF. 

Key words thermoplastic thermosetting polymers, carbon-aramid- glass-fibre and nano-fibre composites, land- sea-space-environments, composite manufacturing technologies, wind- tidal- wave- space- generators. 

As with advanced polymer composite, a nanocomposite is formed from the combination of two or more materials however, one of the materials has nanoscale (< 100 nm) dimensions. Nanoparticles can be classified into three categories depending on the number of their nanoscale dimensions (i) nano-spheres (ii) nano-fibres and (iii) nano-plates, having three, two and one nanoscale dimension, respectively, Thostenson et al. (2005). Paul and Robeson (2008) have given a comprehensive review of nanoparticles. Only nano-fibres and nano-plates will be mentioned in this chapter, as these are relevant to possible structures concerned with sustainable energy. 

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