Electrical properties carbon fiber reinforcement

Carbon fiber-reinforced PAs may be used for conductive and electrical shielding applications where high mechanical properties are also required, and for applications requiring a measure of internal lubrication, slip and good wear-resistance. Mineral-reinforced PA (with talc or mica) offers very good dimensional stability, and low shrinkage and warpage. 

CFRPs are strong and light fiber-reinforced polymers. Carbon fibers are a new breed of high-strength materials. Carbon fiber contains at least 90% carbon prepared by controlled pyrolysis of rayon fibers [34]. The subsistence of carbon fiber came into use in 1879 when Edison took a patent for the fabrication of carbon filaments used in electric lamps [35]. The composites manufactured using carbon fiber reinforcements exhibit a range of mechanical properties suitable for many constructional, industrial, and automobile applications. 

The electrical properties of pitch based semi-conductive carbon fibers have been determined by Okubo et al [191] and Gerteisen [192] examined carbon fiber reinforced thermoplastics with controlled surface resistivity. The techniques used for measuring the conductivity in carbon fibers have been described by Maslii and Panasenko [193]. 

EFFECT OF CARBON FIBER REINFORCEMENT ON ELECTRICAL PROPERTIES OF POLYMERS... 

Electrical properties have been reported on numerous carbon fiber-reinforced polymers, including carbon nanoflber-modified thermotropic liquid crystalline polymers [53], low-density polyethylene [54], ethylene vinyl acetate [55], wire coating varnishes [56], polydimethyl siloxane polypyrrole composites [50], polyacrylonitrile [59], polycarbonate [58], polyacrylonitrile-polycarbonate composites [58], modified chrome polymers [59], lithium trifluoromethane sulfonamide-doped polystyrene-block copolymer [60], boron-containing polyvinyl alcohols [71], lanthanum tetrafluoride complexed ethylene oxide [151, 72, 73], polycarbonate-acrylonitrile diene [44], polyethylene deoxythiophe-nel, blends of polystyrene sulfonate, polyvinyl chloride and polyethylene oxide [43], poly-pyrrole [61], polypyrrole-polypropylene-montmorillonite composites [62], polydimethyl siloxane-polypyrrole composites [63], polyaniline [46], epoxy resin-polyaniline dodecyl benzene sulfonic acid blends [64], and polyaniline-polyamide 6 composites [49]. 

Tsotra, P. and Friedrich, K. 2004. Short carbon fiber reinforced epoxy resin/polyaniline blends Their electrical and mechanical properties. Composite Science and Technology 64 2385-2391. 

The excellent mechanical properties of carbon nanotubes and their high electrical and thermal conductivity make them ideal candidates for a wide range of applications where long carbon fiber-reinforced polymers cannot be employed. The present chapter shows the potential of the CNT as nanofillers in polymers, but also the need of further development for the achievement of optimal dispersion and orientation in order to attain the best possible properties. 

In addition to glass fibers, PBT can also be reinforced with carbon fibers. Many of the general trends seen with glass fibers are also observed with carbon fibers. One important aspect of carbon fibers is that they may bring electrical conductivity to PBT if sufficient fiber connectivity is achieved in the final part. Metal fibers and metal-coated carbon fibers have also been compounded with PBT, giving not only improved mechanical properties but also molded parts with enhanced ability to shield components from electromotive and radiofrequency interference (EMI-RFI) [33],... 

For applications where only mechanical properties are relevant, it is often sufficient to use resins for the filling and we end up with carbon-reinforced polymer structures. Such materials [23] can be soft, like the family of poly-butadiene materials leading to rubber or tires. The transport properties of the carbon fibers lead to some limited improvement of the transport properties of the polymer. If carbon nanotubes with their extensive propensity of percolation are used [24], then a compromise between mechanical reinforcement and improvement of electrical and thermal stability is possible provided one solves the severe challenge of homogeneous mixing of binder and filler phases. For the macroscopic carbon fibers this is less of a problem, in particular when advanced techniques of vacuum infiltration of the fluid resin precursor and suitable chemical functionalization of the carbon fiber are applied. 

The electrical SHM of composites refies on the material itself to act as the sensor. Carbon fibers are electrically conductive the epoxy resin is an insulator. The CFRP composite is somehow conductive because the densely packed carbon fibers may touch each other. As damage (e.g., cracks and delamination) takes place in the composite, the electric conductivity is expected to change. The glass fiber-reinforced polymer (GFRP) composite is a nonconductive insulator with certain dielectric properties. Damage in GFRP composites creates microcracks and even... 

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