Commercial applications carbon fibers

Because of their unique blend of properties, composites reinforced with high performance carbon fibers find use in many structural applications. However, it is possible to produce carbon fibers with very different properties, depending on the precursor used and processing conditions employed. Commercially, continuous high performance carbon fibers currently are formed from two precursor fibers, polyacrylonitrile (PAN) and mesophase pitch. The PAN-based carbon fiber dominates the ultra-high strength, high temperature fiber market (and represents about 90% of the total carbon fiber production), while the mesophase pitch fibers can achieve stiffnesses and thermal conductivities unsurpassed by any other continuous fiber. This chapter compares the processes, structures, and properties of these two classes of fibers. 

The number of such examples, however, is not high. In many other examples of advanced-performance materials, such as DuPont s Kevlar and Allied Signal s SPECTRA, the volume applications associated with system-for-system substitution has not yet occurred at a level necessary to pay back the development and commercialization costs already expended. High-performance ceramics is another area in which the early promise has yet to materialize. The consequences of Eckstut s life-cycle dynamics have been overcapacity and severe rationalization in high-performance carbon fiber businesses, some specialty alloy activities, and high-performance polymer composites. Thus, with critical technologies that involve advanced-performance materials, we need to better understand how to exploit their value in a commercially viable way. 

Synthetic carbonaceous materials are widely used in these applications. Several types of synthetic materials (e.g. graphitized mesophase carbon microbeads (MCMB), graphitized milled carbon fiber, and even, initially, hard carbons) became the materials of choice at the time of commercialization of first successful lithium-ion batteries in late 1980s. New trends, mainly driven by cost reduction and need for improved performance, currently shift focus towards application of natural graphite. 

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. 

Carbon fiber introduction into commercial markets happened in the mid-1960s and since then their application has increased substantially. Some of these applications include airplanes, spacecraft parts, compressed gas tanks, automotive parts, bridges, reinforced concrete, structural reinforcement, recreational sports equipment, and electrochemical systems [6,7]. 

The surface properties of carbon fibers are intimately related to the internal structure of the fiber itself, which needs to be understood if the surface properties are to be modified for specific end applications. Carbon fibers have been made from a number of different precursors, including polyacrylonitrile (PAN), rayon (cellulose) and mesophase pitch. The majority of commercial carbon fibers currently produced are based on PAN, while those based on rayon and pitch are produced in very limited quantities for special applications. Therefore, the discussion of fiber surface treatments in this section is mostly related to PAN-based carbon fibers, unless otherwise specified. 

Poly[2,2 -(m-phenylene-5,5 -benzimidazole)] (PBI) is a very high glass transition temperature (Tg 430°C), commercially available material. It possesses excellent mechanical properties, but is difficult to process into large parts and has high moisture regain and poor thermo-oxidative stability at temperatures above approximately 260 °C. Polyimides, especially the thermoplastic polyimides, offer attractive thermo-oxidative stability and processibility, but often lack the thermal and mechanical characteristics necessary to perform in applications such as the matrix for high use-temperature (over 300 °C) structural composites (for example, carbon fiber reinforced) for aerospace use. The attempt to mitigate... 

The design of the first commercial modules has allowed the commercial application of membrane contactors for some specific operations. This is the case of the Membrana-Charlotte Company (USA) that developed the LiquiCel modules, equipped with polypropylene hollow fibers, for the water deoxygenation for the semiconductor industry. LiquiCel modules have been also applied to the bubble-free carbonation of Pepsi, in the bottling plant of West Virginia [18], and to the concentrations of fruit and vegetable juices in an osmotic distillation pilot plant at Melbourne [19]. Other commercial applications of LiquiCel are the dissolved-gases removal from water, the decarbonation and nitrogenation in breweries, and the ammonia removal from wastewater [20]. 

High-strength carbon fibers have been produced since 1950s, but ACFs have been available commercially only recently. An activation step is necessary starting from the carbon fibers. Excellent reviews of the development of and studies on ACFs have been made by Suzuki (1994) and Rouquerol, Rouquerol and Sing (1999). Many possible novel applications of the ACF s have been reported (Suzuki, 1994 Kaneko, 2000). 

Pitch-Based General Performance Carbon Fiber (GPCF). As described in the introduction, continuous-strand GPCF has been produced commercially only by the Kureha Chemical Industries Company. Public attention has recently been attracted to this type of carbon fiber by the success in using carbon-fiber-reinforced concrete in the construction of the Arsasheed Monument in Iraq (24) by the Kashima Construction (Kashima Kensetsu) Co. Future construction projects in Japan plan to utilize further this type of fiber-reinforced concrete. Such applications may lead to mass consumption of fiber if its price can be brought below 9/kg ( 4/lb). The authors believe that some substantial reductions in the price of the general-performance fiber, perhaps to 6.5/kg ( 3/lb), may occur in the near future. 

In comparison with the USA, the aerospace and defense industries of Japan are quite small. This is the principal reason for the relatively slow commercialization of pitch-based high-performance carbon fiber (HPCF) in Japan. As incentive for the HPCF industry, other fields of applications must be sought. In general, the... 

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