Carbon Fiber Property Comparison

PAN fibers develop a structure with little point-to-point relationship between atoms in neighboring basal planes. This structure is labeled the turbostratic configuration and is characterized by interplanar spacing values greater than 0.344 nm. The crystallite size in the direction normal to the basal planes, or stack height (L, ), in turbostratic graphite is typically less than 5 nm. 

Since PAN-based carbon fibers tend to be fibrillar in texture, they are unable to develop any extended graphitic structure. Hence, the modulus of a PAN-based fiber is considerably less than the theoretical value (a limit which is nearly achieved by mesophase fibers), as shown in Fig. 9. On the other hand, most commercial PAN-based fibers exhibit higher tensile strengths than mesophase-based fibers. This can be attributed to the fact that the tensile strength of a brittle material is eontrolled by struetural flaws [58]. Their extended graphitic structure makes mesophase fibers more prone to this type of flaw. The impure nature of the pitch preciusor also contributes to their lower strengths. 

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Figure 5.16 The mean interlayer spacing of PAN based and MPP based carbon fibers in comparison with a well graphitizing coke. Source Reprinted with permission from Fitzer E, PAN-based carbon fibers-present state and trend of the technology from the viewpoint of possibilities and limits to influence and control the fiber properties by the process parameters, Carbon, 27(5), 621-645, 1989. Copyright 1989, Elsevier.

TABLE I. Representative properties of carbon fibers and comparisons... 

POLYMAT light can be used for time saving and comprehensive selection of materials according to a customer s application profile employment of reasonably priced alternative materials with comparable properties in plastics manufacture searching for alternative manufacturers in case of delivery problems comparison of different plastics materials for a single production task market analyses, e.g. a search for manufacturers producing PA 6 with a content of 30% carbon fibers. 

Perhaps even more important than their structures, most of these polymers are frequently reinforced by glass fibers or even carbon fibers, which contribute tremendously to their properties, and must be considered in any comparison of their practical performance. Reinforcing fibers generally raise modulus 2-4 fold and usually increase breaking strength somewhat. In crystalline plastics, they often raise maximum use temperatures dramatically. 

From these comparisons it is clear that every quantum improvement in the fatigue cycles can be attributed to the plasma surface modifications of fillers. Among the improvement of fatigue properties by the plasma treatments on the carbon fibers, as shown in Figure 30.28, the oxygen plasma posttreatment showed a better effect that was already seen in the plasma treatment on the X-ray opaque powder. There were reports that the oxygen plasma-treated surface showed a better adhesion to PMMA than the argon plasma-treated surface [46 9]. 

FIGURE 12.11 Improvements of the mechanical properties of three-dimensional reinforced CMCs by hybrid infiltration routes (a) R.T. flexural stress-strain plots for a three-dimensional carbon fiber reinforced composite before and after cycles of infiltration (comparison between eight cycles with zirconium propoxide and fonr cycles pins a last infiltration with aluminum-silicon ester (b) plot of the mechanical strength as a fnnction of the final open porosity for composites and matrix of equivalent porosity, before and after infiltration (Reprinted from Colomban, R and Wey, M., Sol-gel control of the matrix net-shape sintering in 3D reinforced ceramic matrix composites, J. Eur. Ceram. Soc., 17, 1475, 1997. With permission from Elsevier) (c) R.T. tensile behavior (d) comparison of the R.T. mechanical strength after thermal treatments at various temperatures. (Reprinted from Colomban, R, Tailoring of the nano/microstructure of heterogeneous ceramics by sol-gel routes, Ceram. Trans., 95, 243, 1998. With permission from The American Ceramic Society.)... 

Mechanical Properties. To reveal the reinforcing effect of liquid crystalline polymer microfibrils on the mechanical properties of the films both their dynamic torsional moduli and dynamic tensile moduli have been studied as a function of temperature using a Rheometrics Mechanical Spectrometer (RMS 800) and a Rheometrics Solids Analyzer (RSA II), respectively. For comparison purpose the modulus of neat matrix polymers and, in some cases, the modulus of carbon fiber and Kevelar fiber reinforced composites has also been measured. 

Comparison between properties of activated carbon fibers and granular activated carbons... 

Other advantage of ACFs is the possibility to prepare woven clothes and nonwoven mats, which developed new applications in small purification systems for water treatment and also as a deodorant in refrigerators in houses, recently reported. In order to give the fibers an antibacterial function and to increase their deodorant fimetion, some trials on supporting minute particles of different metals, such as Ag, Cu and Mn, were performed. Table 5. 2 presented comparison between properties of activated carbon fibers and granular activated carbons [13-46]. 

In Japan, calcium silicate-SBR latex-glass fiber-based compos-itesi or portland cement-fly ash-SBR latex-carbon fiber-based compos-itesi l have recently received much attention as new artificial wood. Table 8.3 gives die comparison of the properties of the calcium silicate-SBR latex-glass fiber-based artificial wood with natural wood.1 1... 

Figure 15. Transport properties of carbon fibers comparison between the transport properties of carbon fibers and...

Sawada Y, Shindo A, Torsional properties of carbon-fibers, Carbon, 30(4), 619-629, 1992. Swanson SR, Merrick M, Toombes GR, Comparison of torsion tube and losipescu in-plane shear test results for a carbon fibre reinforced epoxy composite, Composites, 16, 8220, 1985. 

Finally, there is a property of high-performance carbon fibers, both PAN and mesophase pitch-based, which sets them apart from other materials. They are not subject to creep or fatigue failure. These are important characteristics for critical applications. In a comparison of materials for tension members of tension leg platforms for deep-.sea oil production de.scribed by Salama (1997), carbon fiber strand survived 2,000,000 stress cycles between 296 and 861 MPa. In comparison, steel pipe stressed between 21 and 220 MPa failed after 300,000 cycles. Creep studies on PAN and... 

The properties of Dyneema fibers in comparison to other high performance fibers have given rise to a real new class of materials. The first diagram gives a plot of specific strength vs specific modulus. Especially in specific strength Dyneema has unique properties and it is clear that there still remain possibilities for further improvement. In specific modulus Dyneema has higher values than aramids and almost equals certain types of carbon fiber. 

Fig. 18a-C. Comparison of processing conditions and properties between microwave and thermally cured carbon fiber reinforced phenylethynyl-terminated polyimide composites (PETI-5/IM7) composites. Reprinted from (1999) J Polym Sci A Polym Chem 37 4616 [83] with per-...

However, some other orthopedic implantable medical devices including carbon fiber have shown successful results. Carbon-fiber-reinforced polyetheretherketone (CFR-PEEK) has been reviewed by Li et al. [13] to assess properties, technical data, and safety in orthopedic applications. CFR-PEEK may be an ideal material as it has a modulus very similar to bone and an ability to withstand prolonged fatigue strain. It can also be manufactured to match the modulus of both cortical and cancellous bone densities. This review shows no breakdown over time, while CFR-PEEK is readily accepted by the body. One reported study done by Steinberg et al. [48] makes a comparison between commercially available devices and CFR-Peek substitutes for wear/debris. The wear/debris was assessed based on the amount of the debris generated... 

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