Carbon graphitic fiber difference

Fibers produced by the pyrolysis of organic precursor fibers, such as rayon, polyacrylonitrile (PAN), and pitch, in an inert environment. The term is often used interchangeably with the term graphite however, carbon fibers and graphite fibers differ. The differences lie in the temperature at which the fibers are made and heat-treated, as well as in the amount of elemental carbon produced. Carbon fibers typically are carbonized at around 1,315 °C and contain 94 1 % carbon, while graphite fibers are graphitized at 1,900-2,480 °C and contain 99 % carbon. 

More than 95% of current carbon fiber production for advanced composite appHcations is based on the thermal conversion of polyacrylonitrile (PAN) or pitch precursors to carbon or graphite fibers. Generally, the conversion of PAN or pitch precursor to carbon fiber involves similar process steps fiber formation, ie, spinning, stabilization to thermoset the fiber, carbonization—graphitization, surface treatment, and sizing. Schematic process flow diagrams are shown in Eigure 4. However, specific process details differ. 

Carbon electrodes are commercially available in many forms. These include plates, foams, felts, cloths, fibers, spherical and other particles suitable for beds or powders. Graphite or amorphous carbons exhibit quite different performances. Porosity, surface area and pretreatment are important variables to be considered in designing carbon electrodes. 

Different kinds of carbon-intense fibers are used, the most common being carbon and graphite fibers, and carbon black. As is the case with fibrous glass, surface voids are present. Carbon-intense fibers are often surface-treated with agents such as low molecular weight epoxy resins. Such surface treatments also aim at increasing the fiber-matrix adhesion. 

Recall from Section 1.4.5.1 that there are two primary types of carbon fibers polyacrylonitrile (PAN)-based and pitch-based. There are also different structural forms of these fibers, such as amorphous carbon and crystalline (graphite) fibers. Typically, PAN-based carbon fibers are 93-95% carbon, whereas graphite fibers are usually 99+%, although the terms carbon and graphite are often used interchangeably. We will not try to burden ourselves with too many distinctions here, since the point is to simply introduce the relative benefits of continuous-fiber composites over other types of composites, and not to investigate the minute differences between the various types of carbon-fiber-based composites. The interested reader is referred to the abundance of literature on carbon-fiber-reinforced composites to discern these differences. 

RPs that combine two different materials (plastic matrix and reinforcement) are a separate major and important segment in the plastic industry. They are also called plastic composites and composites. There are also self-reinforcing plastics such as liquid crystal polymers (Chapter 1) and others.301 It is a fact that RPs have not come near to realizing their great potential in a multitude of applications usually due to cost limitations that particularly involves the use of expensive fiber reinforcements (carbon, graphite, silica, etc.).1 Information on thermoplastic and thermoset plastic RPs are reviewed in Chapter 15. 

Whenever a new material is discovered, the focus quickly shifts from fundamental research to the more applied aspects. Fullerenes and carbon nanotubes are no different in that respect. In the case of fullerenes thousands of new materials are synthesized, but a market-suitable product is not yet available. Perhaps the carbon nanotubes are closer to applications. Graphite fibers have proven to be very useful and nanotubes are at the very least, an extreme in the spectrum of the graphite fiber size scale. They retain many of the favorable properties of graphite and add to them new properties related to their nanoscopic size, as pointed out above. Directions that appear to have some promise involve different properties. Nanotube lamps and displays are already looming on the horizon. Also, nanotube films may be used as electrodes in solid state heterostructures [182]. 

Here, the sorption of viscous organics, heavy oils, different oils such as engine and cooking oils, and also biomedical fluids are discussed on macroporous carbon materials, mainly three kinds of materials, i.e., exfohated graphite, carbonized fir fibers, and carbon fiber felts. The recovery of sorbed heavy oils from macroporous carbon materials is also discussed. 

Kinetics of sorption into carbon materials for different oils was studied by using the so-called wicking method [31]. The system for the measurement is schematically shown in Fig. 27.11(a). The mass increase by capillary suction of oils from the bottom into carbon sorbents, either exfoliated graphite or carbonized fir fibers packed into a glass tube with a cross-sectional area of 314 mm with different densities or carbon fiber felts cut into similar cross-sectional area, was measured at room temperature as a function of time. The change in the mass of carbon sorbents due to the sorption of oils was plotted against time (sorption curve) as shown in Fig. 27.11(b). 

Dandekar and co-workers investigated the surface chemistry of three different forms of carbon, (i.e., activated carbon, graphitized carbon fibers and diamond powder) by means of TPD combined with TR spectroscopy [236]. The samples were studied as-received as well as after either a nitric acid treatment to introduce oxygen functional groups on its surface or a... 

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