Poly insulating polymer composite

Numerous polymer compositions are applied as electrical insulation. Some of them are only used in small volumes for special applications. The materials used in relatively large volume in 1980 are polyethylene (high density + low density), 211,000 tons poly(vinyl chloride) (PVC), 177,000 tons and polyesters, 77,000 tons. 

Miscellaneous Extrusion-Applied Polymers. As mentioned earlier, there is a tendency to develop solventless magnet wire enamel formulations, and extrudable polymer systems would fulfill that requirement. There have been reports about extrusion of thin coatings of polyesters over copper wire. At this point, the state of the art allows extrusion of thin insulating films only with thermoplastic materials. The reliable extrusion of uniform and concentric insulating films of approximately 0.001-0.002 in. wall thickness is already an improvement over the more traditional extrusions of polyethylene, poly(vinyl chloride), and several fluoropolymers in much greater wall thicknesses. Because cross-linked insulation is ultimately required for most magnet wire applications, further materials development needs to be done to provide polymer compositions that are both extrudable as thin films and can be cross-linked in an economical process suitable for large-scale industrial application. 

Transparent SWNT/insulating polymer nanocomposites have not been made with high conductivity values, mainly because of the intrinsic charge localization arising from insulating polymer dispersant. In a direct comparison, SWNTs were stabilized with insulating surfactant (SDS) or conductive poly(3,4-ethylenedioxythiophene) (PEDOT) PSS. " Both SWNT dispersions were introduced into a polystyrene matrix via a latex-based route. Composites with PEDOT PSS-stabilized SWNTs showed a percolation threshold of 0.18 wt% and a conductivity value of 500 S m compared with 3.8 wt% and 20 S m for the SDS-based composites, respectively. The authors attributed the conductivity enhancement to conduction bridge formed by the conductive polymer between adjacent SWNTs. 

Films prepared in a similar manner with Hydrin C are those utilizing poly(N,N -dimethyl-2,2 -bipyrrole) [220], and polypyrrole [221]. Electrochromic films of Hydrin C and poly(o-methoxyaniline) have also been produced in which the aniline polymer is chemically polymerized in the presence of p-toluene sulfonic acid and blended with Hydrin C with the blend cast from solution [219]. Another example in which an electrochromic polymer was electrochemically polymerized in the presence of an insulating polymer is that of polypyrrole-polyjether urethane) or polypyrrole-poly(ethylene-co-vinyl alcohol) composite films [222]. Both films switched between a yellow reduced state to a bluish brown oxidized state, similar to polypyrrole. 

Ext ive investigations on polyaniline (PAn) and its derivatives have be carried out (i) since they possess a moderate conductivity upon doping with protonic acid and an excellent stability under ambient conations (2,3). PAn is simply prepared by the chemical and electrochemical oxidation of aniline or its derivatives in aqueous solution. In general, however, the chemical and electrochemical polymerization of aniline monomer lead merely to an insoluble powder and a thin brittle film, respectively. Hence, it is very difficult to process PAn for a practical use. In order to deal well with this problem, the improvement of processability of PAn has been studied by preparing polymer composites (4) and soluble PAn (5,6) and using plasma polymerization (7) and postsulfonation of PAn (8,9). Another approadi to the preparation of processible PAn is to apply a precursor polymer, e.g., PAn can be produced by the thermal treatment of poly(anthranilic acid) 0 ANA) (10). This mefliod is particularly useful for the preparation of processible PAn or its composites with other insulating polymers since it does not use external dopants that often cause an inconvenient situation associated with a practical use of the conducting polymer. 

New composite materials were produced by electropolymerizing pyrrole on an insulating polymer coating such as poly(vinyl chloride) (PVC) 289.290) con-... 

Poly(o-alkoxyanilines) are soluble in organic solvents in the doped and conductive form. Thus, they can be blended with insulating polymers by codissolution. This method was used to cast flexible, free-standing and stretchable films of blends of various compositions of poly(o-alkoxyaniline) and poly(vinylidenefluoride)... 

Acrylic polyesters are also used by the polymer industry to produce fibers. However, the blends and composites of this class of polymers with conductive polymers were systematically prepared in the form of films One of the first attempts involved the electrochemical polymerization of 3-methylthiophene using an electrolyte solution containing poly(methyl methacrylate) [92]. By this method poly(methyl methacrylate) is codeposited on the electrode with the conductive polymer, forming a self-supported film. The conductivity of the film on the electrode side was two orders of magnitude higher than on the electrolyte side. Cyclic voltammetry and the visible spectra of the blend reproduce exactly the curves for the pure conductive polymer. This one-step synthesis is an alternative to the electrode coating method, provided that the insulating polymer host is soluble in the electrolyte solution. 

G. Droval, J.-F. Feller, P. Salagnac and P. Glouannec. Thermal conductivity enhancement of electrically insulating syndiotactic poly(styrene) matrix for diphasic conductive polymer composites. Polymers for advanced technology 2006, 17 732-745... 

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