Nylon electrical conductivity

Electrical Properties. Nylon has low electrical conductivity (high electrical resistivity) and behaves like an insulator. Nylon-6 has a resistivity of 6 X lO " Hem when dry and a resistivity of 2 x lO " Hem when conditioned at 100% rh at 20°C (44) nylon-6,6 responds similarly. 

Practical appHcations have been reported for PVP/ceUulosics (108,119,120) and PVP/polysulfones (121,122) in membrane separation technology, eg, in the manufacture of dialysis membranes. Electrically conductive polymers of polyaruline are rendered more soluble and hence easier to process by complexation with PVP (123). Addition of small amounts of PVP to nylon 66 and 610 causes significant morphological changes, resulting in fewer but more regular spherulites (124). 

While carbon fiber (thickness on the order of 1000 nm) composites offer very strong materials, carbon nanotubes make even stronger composites. These carbon nanotubes have aspect ratios of over 1000 (ratio of length to diameter). Further, because some carbon nanotubes are electrically conductive, composites containing them can be made to be conductive. A number of carbon nanotube matrixes have been made including using a number of engineering resins, such as polyesters, nylons, polycarbonates, and PPE. 

Nakajima, T., and K. Torii Temperature dependence of the electrical conductivity of nylon. Rep. Prog. Polymer Phys., Japan 5, 209 (1962). 

Except for gold and silver, copper is the best metallic electrical conductor and copper wires are commonly used as electrical conductors. They are also used as magnet wires in electric motors, transformers, generators, electromagnets, etc. Copper and aluminum are commonly used for magnet wire because of their good electrical conductivity. Magnet wires are frequently coated by a variety of polymers such as nylon, aramid, polyester, polytetrafluoroethylene, polymide, etc. 

An important development, pioneered by Kuhn and coworkers,37 38 has been the deposition of conducting PAn s onto fibers and fabrics. Not only hydrophobic fibers such as polyesters and polypropylene but also hydrophilic textiles such as rayon and cotton can be coated with PAn with this in situ polymerization method. PAn/nylon-6 composite films have also been prepared by adsorbing aniline onto thin nylon-6 films and then treating with aqueous (Nn4)2S208.39 The composite films exhibited a low percolation threshold requiring just 4% PAn for electrical conductivity. 

Another study by Hong et al. also reports the preparation of conducting PANI/nylon-6 composites with high electrical conductivity and superior mechanical properties, such as flexibility and lightness [24]. PANI was chemically polymerized on the surface of the nylon-6 electrospun nanofiber webs. The electrical conductivity measurements showed that the conductivity of the PANI/nylon-6 composite electrospun fiber webs was superior to that of PANI/nylon-6 plain-weave fabrics because of the high surface area/volume ratios. The volume conductivities of the PANI/nylon-6 composite electrospun fiber webs increased from 0.5 to 1.5 S cm as the di sion time increased from 10 min to 4h because of the even distribution of PANI in the electrospun fiber webs. However, the surface conductivities of the PANI/nylon-6 composite electrospun fiber webs somewhat decreased from 0.22 to 0.14 S cm as the di sion time increased, probably because PANI was contaminated with aniline monomers, aniline oligomers, and some alkyl chains, which served as electrical resistants. 

Later, systematic study of EMI shielding behavior of highly conducting thermoplastic PANI/PVC and PANI/nylon blends (-0.1-20 S/cm) presented the theoretical as well as experimental aspects of SE in the 1 MHz to 3 GHz frequency range [18,70,113]. It was observed that both near- and far-filed SE followed the D.C. electrical conductivity and exhibited rapid initial rise followed by slow increment at higher conductivity (Figure 9.11b). 

Electrospinning is applicable to a wide range of polymers like those used in conventional spinning, that is, polyolefine, polyamides, polyester, aramide, and acrylic, as well as biopolymers like proteins, DNA, and polypeptides, or others like electrically conducting, photonic and other polymers such as poly(ethylene oxide] (PEO], DNA, poly(acrylic acid] (PAA], polyQactic acid] (PEA], and also collagen, organics such as nylon, polyester, and acryl resin, and poly(vinyl alcohol] (PVA], polystyrene (PS], polyacrylonitrile (PAN], peptide, cellulose, etc. 

PANl nanoparticles were doped with DBSA and electrospun with nylon-6 by Hong et al. Conductivities of different forms were compared. The electrical conductivity of PANl (DBSA) particle pellets was about 4.27 x 10 S/cm, the conductivity of the PANl (DBSA)-nylon-6 film was about 1.68 x 10 S/cm, and the conductivity of the PANl (DBSA)-nylon 6 electrospun fiber web was about 6.19 x 10" S/ cm. It was concluded that when the PANl (DBSA-nylon 6) composite solution was electrospun by electric power, the overall crystallinity of the composite polymer decreased so the conductivity decreased. This was explained with the rapid evaporation of the solvent during the electrospinning process. 

The in situ polymerization of aniline to form an electrically conductive textile was also first reported by Kuhn and coworkers [78,79] in which the polyaniline was deposited onto a textile substrate from an aqueous solution containing aniline, ammonium persulfate, hydrochloric acid, and either the disodium salt of 2,6-naphthalenedisulfonic acid or 1,3-benzenedisulfonic acid. In these studies, the polymerization conditions were controlled in order to deposit the polyaniline layer only onto the textile support with no polymer precipitating in the bulk liquid phase. This was accomplished by using dilute solutions of aniline (0.03 M). A subsequent study by Tzou and Gregory [92] on the deposition of polyaniline to nylon-6 fibers was focused on investigating the reaction kinetics of the chemically oxidative polymerization of aniline... 

Figure 6.92 Stress vs. strain at various temperatures for SABIC Innovative Plastics LNP Thermocomp RC006— electrically conductive, 30% carbon fiber filled Nylon 66 resin (DAM).

Composite-skinned honeycomb panels These may use Nomex nylon paper honeycomb core, aluminium honeycomb or sometimes PVC (polyurethane or acrylic foam core). Dents are not acceptable in composite skins as they indicate fibre damage. Nomex core may split under a dent, so any such damage needs to be cut out and repaired. Nomex honeycomb can absorb considerable amounts of moisture. Wet honeycomb should be thoroughly dried or replaced. Moisture meters are available for use with Fibreglass, Kevlar or Nomex, but these meters will not work with carbon fibre because it is electrically conductive. Instruments that can indicate when carbon-fibre composites are dry enough to repair are few in number and very expensive. 

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