Carbon fiber shielding effects

Carbon—carbon composites are used in high temperature service for aerospace and aircraft appHcations as weU as for corrosion-resistant industrial pipes and housings. AppHcations include rocket nozzles and cases, aircraft brakes, and sateUite stmctures. Carbonized phenoHc resin with graphite fiber functioned effectively as the ablative shield in orbital re-entry vehicles for many years (92). 

Ethylene-vinyl acetate Fetterman [37] reinforced compounded ethylene-vinyl acetate (EVA) copolymer by using short hbers and found that silane coupling agents were effective at establishing improved hber-matrix adhesion. Das et al. [38] prepared carbon fiber-filled conductive composites based on EVA and studied the electromagnetic interference shielding effectiveness of the composites. 

Figure 15.2. Shielding effectiveness of nickel-coated carbon fiber in ABS depending on method of mixing. [Adapted, by permission. I om Guanghong Lu, Xiaotian Li, Hancheng Jiang, Composites Sci. Technol., 56, No.2, 1996,193-200.]...

Nanocomposites refer to the combination of nanosized fillers (10 m diameter) with polymers, rather than the combination of polymer matrix (filled with nanoparticles) and fiber reinforcement The most popular fillers used as fire retardants are layered silicates. Loading of 10% or less (by weight) of such fillers significantly reduces peak heat release rates and facilitates greater char production [7]. The char layer provides a shielding effect for the composites below and the creation of char also reduces the toxicity of the combustion products, as less carbon is available to form the CO and CO2. 

Effective shielding capability may be achieved by incorporating electrically conductive materials, especially carbon fibers or carbon filaments, into the concrete mix. Owing to... 

The addition of 1.7% v/v of a pitch based carbon fiber lowered the electrical resistivity of a gypsum plaster (o -CaS04-5H20) and significantly improved the effective EMI shielding [59]. 

Huang CY, Pai JF, Optimum conditions of electrolessNi plating on carbon fibers for EMI shielding effectiveness of ENCF/ABS composites, Eur Polym J, 34(2), 261-267, 1998. 

C for up to 144 hours) on the properties of the composites. For all fillers, an EMI shielding effectiveness of greater than 50 dB was achieved for stainless steel and nickel fibers it occurred at a filler volume of 20% for aluminum flakes, at 30% and for carbon fibers, at 40%. 

Wu J, Chung DDL (2002) Increasing the electromagnetic interference shielding effectiveness of carbon fiber polymer-matrix composite by using activated carbon fibers. Carbon 40 (3) 445 67... 

Cao, M.-S., Song, W.-L., Hou, Z.-L., Wen, B., Yuan, J., 2010. The effects of temperature and frequency on the dielectric properties, electromagnetic interference shielding and microwave-absorption of short carbon fiber/silica composites. Carbon 48, 788—796. 

Das NC, ChaM TK, Khastgir D (2001) Electromagnetic interference shielding effectiveness of conductive carbon black and carbon fiber-filled composites based on rubber tmd rubber blends. Adv Polym Technol 20(3) 226-236. doi 10.1002/adv.l018... 

Das NC, Khasgir D, Chaki TK, Chakraborty A (2000) Electromagnetic interference shielding effectiveness of carbon black and carbon fiber fiUed EVA and NR based composites. Compos Part A 31(10) 1069-1081. doi 10.1016/S1359-835X(00)00064-6... 

Huang, C.-Y, Wu, C.-C. The EMI shielding effectiveness of PC/ABS/nickel-coated-carbon-fibre composites , Europ. Polym. J. 36(12) (2000), 2729—2737 Hirase, R., Hasegawa, M., Shirai, M. Conductive fibers based on poly(ethylene terephthalate)-polyaniline composites manufactured by electrochemical polymerization , J. Appl. Polym. Sci. 87(7) (2003), 1073—1078 Pbtschke, R, Briinig, H., Janke, A., Fischer, D., Jehnichen, D., Orientation of multi-walled carbon nanotubes in composites with polycarbonate by melt spinning , Polymer 46(23) (2005), 10355-10363... 

The electrical properties of blends of thermoplastic polymer, inherently conductive polymer (ICP) and metallized carbon fiber were studied. Both electrical resistance and electromagnetic shielding effectiveness were measured. These results were compared with the data for blends of thermoplastic polymer and metallized carbon fibers. The electrical resistance of the blends with ICP was much lower than that of the blends without. Additionally, the magnitude of the shielding effectiveness for the blends with inherently conductive polymer was higher than the blend without. The shape of the curves was different, as well, particularly at lower frequencies. 

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