Active carbon fibers emerging

Detailed accounts of fibers and carbon-carbon composites can be found in several recently published books [1-5]. Here, details of novel carbon fibers and their composites are reported. The manufacture and applications of adsorbent carbon fibers are discussed in Chapter 3. Active carbon fibers are an attractive adsorbent because their small diameters (typically 6-20 pm) offer a kinetic advantage over granular activated carbons whose dimensions are typically 1-5 mm. Moreover, active carbon fibers contain a large volume of mesopores and micropores. Current and emerging applications of active carbon fibers are discussed. The manufacture, structure and properties of high performance fibers are reviewed in Chapter 4, whereas the manufacture and properties of vapor grown fibers and their composites are reported in Chapter 5. Low density (porous) carbon fiber composites have novel properties that make them uniquely suited for certain applications. The properties and applications of novel low density composites developed at Oak Ridge National Laboratory are reported in Chapter 6. 

The major potential application of active carbon fibers is as an adsorbent in environmental control, as outlined in the previous section. However, there is a number of smaller scale, niche applications that seem to be particularly suited to ACF. These emerging applications include the use of ACF in medicine [111 (see also 59,60),112], as capacitors [113-119] and vapor sensors [120], and in refrigeration [121]. The first two of these applications are summarized below. However, there are not many detailed, publicly-available sources describing any of these applications, partly for commercial reasons and partly because the technology is emerging, so any summary is necessarily limited in scope. 

M. Jagtoyen and F. Derbyshire, Novel Activated Carbon Fiber Composites for Removal of VOC s, CD ROM Proceedings, Emerging Solutions to VOC and AirToxics Control, March 4-6, Florida, 1998. 

No consensus has been reached on the roles of physical absorption and chemical bonding when investigating the surface chemistry of carbon fibers and made more difficult by the buried interface. Jones [47] claims that the electrolytic surface treatment process produces a surface on which the known concentration of chemical functionalities cannot be accommodated on the surface of a smooth cylinder. Absorption studies [48] support the fact that erosion could occur and active species can be deposited in the vicinity of intercrystallite voids. Types A and HT fibers have more basal planes that emerge directly to the surface than is the case with HM fiber and hence are more readily surface treated. Hence, it was suggested [49,50] that HM fiber would require an active epoxy group of smaller dimensions that could be accommodated within the micropore. 

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