Carbon fiber production

The property of mesophase that makes it suitable for carbon fiber and premium coke manufacture is that it forms ordered stmctures under stress which persist following carbonization. However, most carbon fiber production in the 1990s is based on polyacrylonitrile (PAN). 

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. 

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 mesophase pitches used for high-modulus carbon fiber production can be formed either by the thermal polymerization of petroleum- or coal tar-based... 

In the years following the Brooks and Taylor discovery, many researchers attempted to produce a mesophase pitch suitable for carbon fiber production. Otani et al. [21] were first to report producing a high-modulus carbon fiber from a "specific pitch-like material." The precursor used was tetrabenzophenazine, and thus, the resulting material might be considered a synthetic pitch. 

Most carbon fibers use PAN as their precursor however, other polymer precursors, such as rayon [8], pitch (a by-product of petroleum or coal-coking industries), phenolic resins, and polyacetylenes [6,7], are available. Each company usually uses different precursor compositions for its products and thus it is difficult to know the exact composition used in most commercially available carbon fiber products. 

An alternative starting material for carbon fiber production is pitch—a complex mixture of fused polyaromatic hydrocarbon clusters that can also be melt-spun into fibers. 

The aromatic pitches produced from CCB-distillate are being developed for pitch carbon fiber production. 

In this entry, the effect of blending recyclable poly-(propylene) (PP) and poly(ethylene terephthalate) (PET) with lignin on carbon fiber production is presented. We discuss the effects of lignin structure and specific intermolecular interactions on lignin thermal properties as well as the effect of blend composition on surface morphology, mechanical properties, and the manufacturing process of lignin/recyclable plastic-based carbon fibers. 

Table 3 Yields of HKL/synthetic polymer blend carbon fibers in each step of carbon fiber production...

A method to prepare nanotubes in a fashion similar to carbon fiber production consists in the pyrolysis of carbon-rich polymers. For example, the thermal... 

By solvent extracting the pitch with a solvent system having a solubility parameter of 8.63 a more or less ideal fraction for carbon fiber production is obtained. Extraction with solvent systems of different solubility parameter results in uniform changes in extracted product characteristics which can be tailored to other specific carbon product applications, such as carbon/carbon matrix materials, anodes, etc. 

MEC (London U.K. and Shanghai, China), an international engineering services company, was awarded a 25 million contract by China Worldbest Group Co. Ltd. (Changzhou, China) to engineer and construct a polyacrylonitrile (PAN) and carbon fiber production plant in Bengbu, a city in Anhui province, located in eastern mainland China. The plant will be the first combined polyacrylonitrile and carbon fiber manufacturing facility built in China. The operation will include production of PAN precursor, which then will be converted into carbon fiber tow at the same location. 

The plant will house all the facilities necessary for raw material preparation and storage, batch polymerization processing (conversion of acrylonitrile monomer into polyacrylonitrile), the spinning of the polymerized product into yarn, all further processing and drying necessary to form the PAN precursor, collection of the precursor on bobbins, and the final pyrolization process that forms the carbon fiber product. 

Carbon fiber/polymer matrix composites are extensively used in sporting goods and recreational applications. This is the second most important field of applications for carbon fibers. It has been largely responsible for the rapid growth of carbon fiber production during the last two decades and hence for the decrease in fiber prices [12-13]. 

There is no doubt that this study sets out many of the ground rules for the present day carbon fiber production process from a PAN precursor but, unfortunately, Shindo and his team failed to exploit the commercial significance of this early work and only patented the process they had used. 

Work at Courtaulds, Coventry 3.4.5.1 Carbon fiber production... 

When the carbon fiber product was removed from the boat, it was bound with some products of carbonization and formed a stiff tow, but when such a tow was passed between the fingers the tow became limp. This boat process ensured that the fiber was heat treated in proximity to the products of carbonization (also called cooking in its own juices ), which certainly did have beneficial properties, presumably healing surface flaws. When continuous fiber first went onstream, the strength of the continuous carbon fiber product was about 0.5 GPa below the strength of the staple product and was attributed to a change in the furnace atmosphere. 

A carbon fiber production line requires a long workshop. The design of such a plant is described in Chapter 10 and the schematic layout of a typical PAN based carbon fiber plant is shown in Figure 10.1. 

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