Micron-size carbon fibers

The presently used micron-sized carbon fibers contain at least 90% carbon and are produced by heat treatment or controlled pyrolysis of different precursor fibers. The... 

Figure 10.2 Molecular structures of polymeric precursors for micron-size carbon fibers.

Micron-sized carbon fibers are synthesized from phenolic resin fibers such as Kynol [27]. The carbon fibers prepared are typically in an activated form, which produces well-developed mesopores for use in applications as high-surface area... 

Carbon nanotubes and carbon nanofibers have been sfudied lately as reinforcement materials for several different polymers because their high modulus and stiffness bear the promise of levels of reinforcement not found with micron-size particles or fibers. This performance can be achieved wifh concentrations... 

Ward and his coworkers investigated the interlayer adhesion in self-reinforced PP composites modified with different nano- and micron-sized particles [27-29]. They found that the introduction of a small amount of carbon nanofibers (CNFs) led to improved performance of polypropylene single-polymer composites obtained by hot compaction of oriented CNF/ PP tapes. The peel strength of a CNF/PP woven fabric composite was significantly increased. In addition, the authors pointed out that the drawn CNF/PP tapes showed substantial voiding around the fibers which were closed and sealed by the hot compaction process. As a result, the composite density increased to its initial value [27]. 

Micron-sized fillers, such as glass fibers, carbonfibers, carbon black, talc, and micronsized silica particles have been considered as conventional fillers. Polymer composites filled with conventional fillers have been widely investigated by both academic and industrial researchers. A wide spectrum of archival reports is available on how these fillers impact the properties. As expected, various fundamental issues of interest to nanocomposites research, such as the state of filler dispersion, filler-matrix interactions, and processing methods, have already been widely analyzed and documented in the context of conventional composites, especially those of carbon black and silica-filled rubber compounds [16], It is worth mentioning that carbon black (CB) could not be considered as a nanofiller. There appears to be a general tendency in contemporary literature to designate CB as a nanofiller - apparently derived from... 

Examples of inert or extender fillers include china clay (kaolin), talc, and calcium carbonate. Calcium carbonate is an important fiUer with a particle size of about one micron. It is a natural product from sedimentary rocks and is separated into chalk, limestone, and marble. In some cases, the calcium carbonate may be treated to improve interaction with the thermoplastic. Glass spheres are also nsed as thermoplastic fillers. They may be either solid or hollow, depending on the particnlar application. Talc is a filler with a lamellar particle shape. ° It is a natural, hydrated magnesium silicate with good slip properties. Kaolin and mica are also natural materials with lamellar structures. Other fillers include wollasto-nite, sihca, barium sulfate, and metal powders. Carbon black is used as a filler primarily in the rubber industry, but it also finds application in thermoplastics for conductivity, UV protection, and as a pigment. Fillers in fiber form are often used in thermoplastics. Types of fibers include cotton, wood flour, fiberglass, and carbon. Table 1.3 shows the fillers and their forms. An overview of some typical fillers and their effect on properties is shown in Table 1.4. 

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