Carbon Fiber Size Content

Ordinarily, an epoxy size can be determined with butan-l-one (MEK) using a soxhlet extraction for 2 h, dried, cooled in a desiccator and weighed. 

A quick method of determining size content is by extracting three times in a flask with cold MEK and drying with a UV lamp. 

Some sizes will necessitate using H2SO4/H2O2 to effect extraction by chemical breakdown of 

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Work at Courtaulds [22,23] in the early 1970s attempted to incorporate carbon fiber in a cement slurry, which was difficult due to the size of the cement particles. They tended to be filtered out by the fiber reinforcement, so a cement with a fine particle size (Swiftcrete, an ultra rapid hardening Portland cement with a maximum diameter of about 45 pm) was used and the fiber spread as thinly as possible, using either an air knife, or a water flume and then held in the spread position by sizing with a water based compatible size such as sodium carboxymethylcellulose [22,23]. These larger particles limit the carbon fiber content to about 5% v/v, but in practice, due to a non-uniform distribution, a value of some 12% v/v was attainable. 

Liu et al. [72] used POSS nanomodification in phenolic resin with carbon fiber reinforcement. SEM analysis showed the production of best charred surface on burnt samples that enhanced the ablation performance. Novel flake graphite was introduced into barium-phenolic resin by Yu and Wan [73]. Nanocomposites were made by roller-coating technology and its ablation property was tested under long pulse laser radiation. Nanocomposites showed better ablation performance compared to the control system. It was also observed that the size of the graphite flake affected the ablation rate [73]. Srikanth et al. [74] prepared ablative nanocomposites by introducing nanosilica into the phenolic resin with carbon fiber reinforcement. Ablation resistance of nanocomposites increased with the nanosilica content up to 2 wt%. However, beyond this point ablation resistance decreased. 

Activated carbon fibers (ACFs) are a fibrous form of activated carbon with carbon content more than 90%. ACFs are relatively new adsorbents for filtration or purification techniques. The unique characteristics of ACFs compared with GAC and RAC could increase the application of activated carbons in various areas. The fiber shape of ACFs can significantly improve the intraparticle adsorption kinetics as compared with RAC and GAC, which are commonly employed in gas-phase and aqueous-phase adsorption. Therefore, ACFs adsorption is a promising technique used for designing adsorption units where intraparticle diffusion resistance is the dominant adsorption factor. As a consequence, the size of adsorption units can be decreased by using ACFs (Yue et al. 2001). 

Figure 10 is a pictorial representation of the space between the cell and electrode surface (the drawing is not to scale) [31]. Following complete fusion of a spherical intracellular vesicle to the plasma membrane, the surface area of the vesicle creates a disk-shaped pore with a radius of 2r. The contents of the vesicle diffuse from this disk and spread at an angle, 9, until they reach the surface of the carbon fiber electrode positioned at a distance, h, away from the cell surface. The electrochemical reaction occurs at an area defined by r, which is representative of the size of each detected vesicle. This being the case, the quantity is related to the vesicle radius and the cell/electrode distance (h) by Eq. (3) [31]. 

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