Rayon-based carbon fibers

In contrast, there is also current interest in investigating PAN-based fibers in low thermal conductivity composites [62], Such fibers are carbonized at low temperature and offer a substitute to rayon-based carbon fibers in composites designed for solid rocket motor nozzles and exit cones. 

Rayon-based carbon fibers, on the other hand, have low thermal conductivity and are, therefore, used for thermal insulation purposes. Examples include the nose cone and leading edges of the U S Space Shuttle Orbiter. Isotropic pitch-based carbon fibers are also used for insulating purposes because of their low thermal conductivity. 

Cellulose based carbon fibers tend to be used for ablative applications, which require lower thermal conductivity and enhanced insulating properties than other carbon-carbon materials. The precursor for this product is rayon, which when carbonized, produces rayon based carbon fibers (RBCF). This type of fiber is usually more porous and weaker, which lowers its effective thermal conductivity. At high temperatures, it oxidizes and/or evaporates without disintegration, producing an evaporative cooling effect. 

The first commercial carbon fibers were based on viscose rayon, a cellulosic precursor, but Polycarbon is now the only current producer of this type of carbon fiber. The properties of rayon-based carbon fibers are listed in Table 20.1. A difficult fiber to produce with a low yield, its main use is in existing space programs. 

The torsional modulus is shown in Figure 20.22 and appears to be governed by the structure of the microsection increasing in the order— mesophase pitch based carbon fiber < rayon based carbon fiber < isotropic pitch based carbof fiber < PAN based carbon fiber. 

C Stacked rayon based carbon fiber cloths/carbon composite (HTT 3000°C). 

RAYON-BASED CARBON FIBERS are CARBON FIBERS made from rayon (ceUulose) precursor fibers. 

Note RAYON-BASED CARBON FIBERS have a more isotropic structure than similarly heat treated polyacrylonitrile (PAN) or MESOPHASE PITCH (MPP) BASED CARBON FIBERS. Their Young s modulus values are, therefore, drastically lower (< 100 GPa). RAYON BASED CARBON FIBERS can be transformed into anisotropic CARBON FIBERS with high strength... 

For applications that do not require exceptional mechanical properties, carbon fibers made from high performance aramid polymers show considerable potential. These aramid fibers do not require stabilization prior to carbonization, which substantially simplifies the production process. Rayon-based carbon fibers continue to appear in some composite applications, but have become key substrates for the development of activated carbon fibers. These ACFs develop a microp-orous surface structure that is ideal for adsorption of low levels of volatile organic compounds. 

The properties of stretched-graphitized rayon-based carbon fibers are shown in Table 8.9. The data is to be considered for its historical value, since the material is no longer produced commercially (data from Union Carbide Corp.)... 

Table 8.9. Summary of Physical Properties of Rayon-Based Carbon Fibers...

Carbon-Fiber Network. Rayon-based carbon fibers were used in the early development of carbon-carbon and are still used as carbon felt. PAN-based fibers are now used extensively and pitch-based fibers are under investigation. jhe selection of the carbon-fiber architecture is determined by the application and include felt, short (chopped) fibers, continuous filament such as small-tow T-300 fiber, filament winding or tape-layup, and 3D structures (see Sec. 2.0 above). The effect of carbon-fiber type and architecture is reviewed in Refs. 22 and 23. The effect of carbon-fiber... 

The term carbon fibers type LM is sometimes used for various types of isotropic carbon fibers known as pitch-based or rayon-based carbon fibers that have not been subjected to... 

See carbon fibers, pitch-based carbon fibers, rayon-based carbon fibers... 

Rayon-based carbon fibers are carbon fibers made from rayon (cellulose) precursor fibers. 

It has been more than 50 years that carbon fibers have been under development from rayon, polyacrylonitrile (PAN), isotropic and mesophase pitches. PAN-based technologies are most commercial production of carbon fibers and rayon-based carbon fibers are no longer in production. Pitch-based carbon fibers currently account for niche markets. Isotropic pitch-based carbon fibers have modest level of strength and modulus and are the least expensive carbon fibers. PAN and mesophase-based carbon fibers heat treated to improve modulus. Both PAN and mesophase pitch-based carbon fibers are not subject to creep or fatigue failure and set them apart from other material which is critical for application such as tension leg platforms for deep sea oil production [201]. The new generation of carbon based fibers is carbon nanotube (single and multi-walled). There are different synthesis methods for carbon... 

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