Polyethylene terephthalate electrical properties

Polyesters exhibit excellent high temperature strength and electrical properties making them a good choice for many demanding applications. They also are physiologically inert allowing them to be used in food contact applications. The two common polyesters, polyethylene terephthalate and polybutylene terephthalate, are both used in injection molded products. Polyethylene terephthalate is often used in both extrusion and blow molded processes also. 

Saran (Dow polyvinylidene dichloride) is a tough, chemically resistant plastic available in a variety of forms that are useful in the laboratory. Saran pipe or tubing can easily be welded to itself or sealed to glass and is useful for handling corrosive solutions. Thin Saran film, available commercially as a packaging material, is useful for windows, support films, etc. Mylar (du Pont polyethylene terephthalate) film and other polyester films are also useful for these purposes. Mylar is chemically inert and has excellent electrical properties for electrical insulation and for use as a dielectric medium in capacitors. Much thinner than these are films that can be made in the laboratory by allowing a dilute ethylene dichloride solution of Formvar (polyvinyl acetal) to spread on a water surface and dry. 

PET/PBT (polyethylene terephthalate/polybutylene terephthalate) good colorabUity, excellent surface aesthetics, gloss, chemical resistance, impact, and electrical properties. Apphcations include appliances, electrical apphcations, building and construction. 

Tedlar is moderate in cost and has known long-term performance out-of-doors. It has excellent toughness, good weather resistance, and moderately good electrical and optical performance. Its thermal stress resistance is marginal but adequate (2-6> shrinkage at 150°C) for most needs. Its cost is higher than optimum, but can be used as a thin film, especially when coupled with less expensive polyethylene terephthalate film for better electrical properties at a lower cost. 

It is interesting to mention that the first truly synthetic (not based on natural products) polymer material was bakelite obtained in 1907 via polycondensation of phenol and formaldehyde. This material had good dielectric properties and was used mainly as an electrical insulator. The most famous polycondensation polymer is probably nylon belonging to the class of polyamides. Other common classes of polycondensation polymers are polyesters (like polyethylene terephthalate), polysiloxanes, polycarbonates, polysulfides, polyethers and polyimides. 

Until 2003, Chen s [28], Qu s [29-31], and Hu s [32] groups independently reported nanocomposites with polymeric matrices for the first time the. In Hsueh and Chen s work, exfoUated polyimide/LDH was prepared by in situ polymerization of a mixture of aminobenzoate-modified Mg-Al LDH and polyamic acid (polyimide precursor) in N,N-dimethylactamide [28]. In other work, Chen and Qu successfully synthesized exfoliated polyethylene-g-maleic anhydride (PE-g-MA)/LDH nanocomposites by refluxing in a nonpolar xylene solution of PE-g-MA [29,30]. Then, Li et al. prepared polyfmethyl methacrylate) (PMMA)/MgAl LDH by exfoliation/adsorption with acetone as cosolvent [32]. Since then, polymer/LDH nanocomposites have attracted extensive interest. The wide variety of polymers used for nanocomposite preparation include polyethylene (PE) [29, 30, 33 9], polystyrene (PS) [48, 50-58], poly(propylene carbonate) [59], poly(3-hydroxybutyrate) [60-62], poly(vinyl chloride) [63], syndiotactic polystyrene [64], polyurethane [65], poly[(3-hydroxybutyrate)-co-(3-hydroxyvalerate)] [66], polypropylene (PP) [48, 67-70], nylon 6 [9,71,72], ethylene vinyl acetate copolymer (EVA) [73-77], poly(L-lactide) [78], poly(ethylene terephthalate) [79, 80], poly(caprolactone) [81], poly(p-dioxanone) [82], poly(vinyl alcohol) [83], PMMA [32,47, 48, 57, 84-93], poly(2-hydroxyethyl methacrylate) [94], poly(styrene-co-methyl methacrylate) [95], polyimide [28], and epoxy [96-98]. These nanocomposites often exhibit enhanced mechanical, thermal, optical, and electrical properties and flame retardancy. Among them, the thermal properties and flame retardancy are the most interesting and will be discussed in the following sections. 

The development of flexible printed wiring was made possible through the availability of plastic films that possess high electrical insulation and good chemical resistance, in particular polyethylene terephthalate and polyimide films which account for over 95% of the flexible film consumption for printed wiring applications. The properties of the most important of these polymers are discussed in the following sections. 

Polyethylene terephthalate specialist plastics with a combination of hardness, low coefficient of friction and reasonable electrical properties. 

Polyethylene PET is a thennoplastic polyester made by condensing ethylene glycol terephthalate (PET) and terephthalic acid. PET is stable in a wide range of chemicals and possesses good mechanical, electrical, and thermal properties. It has one of tlie highest densities of the six primary thermoplastics. 

Yesil S, Koysuren 0 and Bayram G (2010) Effect of microfiber reinforcement on the morphology, electrical, and mechanical properties of the polyethylene/poly(ethylene terephthalate)/carbon nanotube composites, Polym Eng Sci 50 2093-2105. 

The large majority of polymers, first of all the broadly used commodity materials polyethylene, polypropylene, poly(ethylene terephthalate) or polystyrene, have similar electrical and optical properties They are insulators and they are colorless, i.e., they possess no mobile charges and the lowest electronic excitations are in the UV region. There exists a peculiar class of polymers with quite different properties these are polymers with conjugated double bonds in the main chain. They are semiconductors or conductors and interact with light. 

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