Silica nano fibers

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. 

Figure 7. SEM of the cut surface from a PDMS modified with silica nano fibers. There are two fibers protruding from the surface and two holes resulting from fibers being pulled free.

Figure 9. Stress strain curves for a PDMS formulated with silica nano fibers. The plots show no significant Mullins effect.

POSS was mechanically dispersed in a functionalized polysiloxane gum using a speedimix (needs some details) and the mix cured using tin catalyzed condensation chemistry. Silica and Carbon nano fiber composites were produced by mixing the fiber into functionalized polysiloxane gum and the mix cured using tin catalyzed condensation chemistry. 

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

Kim and Yang [14] prepared ACNF from electro spun PAN nano fibers activated in steam at 700-800 °C and found that the specific surface area of the ACNF activated at 700 °C was the highest but the Mesopore volume fraction was the lowest. However, the work by Lee et al. [38] showed an opposite result. Song et al. [21] investigated the effect of activation time on the formation of ACNF (ultra-thin PAN fiber based) activated in steam at 1000 °C. Ji et al. [39] made mesoporous ACNF produced from electros-pun PAN nano fibers through physical activation with silica and conducted chemical activations by potassium hydroxide and zinc chloride to increase specific surface area and pore volume of ACNF [40]. It must be pointed out that different methods and conditions of activation lead to very different physical properties and adsorption capacities for ACNF. 

Moreover, there were other reports on the electrospun PI composite Qin et al. reported the fluorescent performance of electrospun PI web mixed with hemicyanine dye (Figure 9), pointed out that the nano fiber structure were helpful to the fluorescence (Qin et al., 2009) Cheng et al. reported the preparation of nonwoven Pl/silica hybrid fabrics by combining electrospinning and controlled in situ sol-gel techniques, their product had better mechanical and thermal properties than ordinary PI electrospun fabrics (Cheng et al., 2009). 

Carbon nanotubes (CNTs) currently attract intense interest because of their unique properties which make them suitable for many industrial applications.28 Carbon nanotubes exhibit some of the properties implied in asbestos toxicity. Carbon nanotubes share with asbestos the fibrous habit - long fibers with a diameter of a few nanometers -and a very high biopersistence. On this basis they are suspected to be hazardous and indeed the first studies in vivo14,29,30 have shown an inflammatory response followed by some evolution towards fibrosis. When inhaled, CNTs may thus constitute a possible hazard to human health. The inflammatory and fibrotic responses elicited by CNTs is similar to that caused by other toxic particles which might be the result of oxidative stress caused by particle- and/or cell-derived free radicals. There is no direct experimental evidence of a capacity of carbon nanotubes to generate free radicals similar to silica asbestos and nano sized iron oxide particles. 

The nanoindentation experiments were conducted at room temperature with a Nano Indenter XP system (MTS Nanoinstruments, Knoxville, TN) using a Berkovich-type diamond tip. Before each test, the system was calibrated using a fused silica. The continuous stiffness mode (CSM) was used in the tests. Thirty randomly selected different fiber and CVI matrix locations were indented for each component of C/C composites. The method of Oliver and Pharr was employed for the elastic modulus calculations. ... 

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