Polyphenylene oxide electrical properties

Polyphenylene oxide)s. Properties Comparison Chart, General Electric Co., Pittsfield, Mass., 1969. 

An important requirement for plastics materials in the automotive industry is paintability alongside metal components in high temperature areas. Noryl GTX series of General Electric has been developed to meet this requirement. The blend consisting of polyphenylene oxide (PPO) in a nylon matrix combines the heat and dimensional stability and the low water absorption of PPO with the flow and semicrystalline properties of nylons. Its impact strength, however, is not as high as PC/PBT blends. 

Polyphenylene oxide (PPO) ru A thermoplastic, linear, non-crystalline polyether obtained by the oxidative polycondensation on 2,6-dimethylphenol in the presence of a copper-amine complex catalyst. The resin has a wide useful temperature range, from below —170 to +190°C, with intermittent use to 205° C possible. It has excellent electrical properties, unusual resistance to acids and bases, and is pro-cessable on conventional extrusion and injection-molding equipment. Because of its high coat PPO is also marketed in the form of polystyrene blends (see Noryf ) that are lower-softening (Tg of PS is about 100°C vs 208°C for PPO), and have working properties intermediate between those of the two resins. 

Conventional insulation materials are of the closed-cell foam type and are unlikely to be used in this application, because the pressure will crush the cells, increasing the thermal conductivity. Yates investigated open-cell foams for use with liquid hydrogen and reported best results with polyphenylene oxide (PPO). This is an anisotropic open-cell material with elongated cells in the depth direction, as developed by General Electric. From Yates data on the thermal conductivity of this material and the known properties of methane. Walker, Stuchly, and Read have estimated that the effective thermal conductivity for PPO foam filled with methane at 7.0 MPa ( 1000 psi) would be of the order of 70 mW/m K. It is, however, very important to note this value is speculative and experimental verification is urgently required. 

Some measurements of this property have been made in a range of electrically conducting polymers. These include epoxy resin/polyaniline-dodecylbenzene sulfonic acid blends [38], polystyrene-black polyphenylene oxide copolymers [38], semiconductor-based polypyrroles [33], titanocene polyesters [40], boron-containing polyvinyl alcohol [41], copper-filled epoxy resin [42], polyethylidene dioxy thiophene-polystyrene sulfonate, polyvinyl chloride, polyethylene oxide [43], polycarbonate/acrylonitrile-butadiene-styrene composites [44], polyethylene oxide complexes with sodium lanthanum tetra-fluoride [45], chlorine-substituted polyaniline [46], polyvinyl pyrolidine-polyvinyl alcohol coupled with potassium bromate tetrafluoromethane sulfonamide [47], doped polystyrene block polyethylene [38, 39], polypyrrole [48], polyaniline-polyamide composites [49], and polydimethyl siloxane-polypyrrole composites [50]. 

D. Electrical Properties Because of the water-resistant nature and low moisture absorption levels, most polyphenylene oxide alloys present good electrical properties over a wide range of humidity and temperature ranges. PPO has a low dielectric constant of 2.58 (at 23°C 60 Hz), a low dissipation factor of 0.00035 and a high glass transition temperature (T ) of approximately 212°C, which are suitable materials for insulating matrices for electrical and electronic devices. 

Property data for GRTP s are presented in two major breakouts. In the first breakout, the basic resins—styrene acrylonitrile (SAN), polycarbonate, polysulfone, polyacetal, polypropylene, polyphenylene oxide (PPG), nylon, modified PPG, and polyvinyl chloride—are treated as the independent variables and the physical, mechanical, electrical, thermal, chemical, and weathering characteristics are treated as the dependent variables. In the second breakout, the functional relationships are reversed, te., the properties are the independent variable and the resins are the dependent variable. ASTM test methods by which the physical values were determined are listed. The. physical data versus resins are presented in both tabular and graphic form. 

TABLE 3-85. ELECTRICAL PROPERTIES OF MODIFIED POLYPHENYLENE OXIDE... 

Polyphenylene oxide Norylen 212 Good electrical properties General General Electric... 

Noryl n Poly(phenylene oxide) Trade name for a family of blends of polyphenylene oxide (PPO) with much less costly styrenic polymers. These blends have the processability, low water absorption, and good dielectric properties associated with polystyrene, while the PPO contributes heat resistance. Glass-reinforced grades are available. Manufactured by General Electric, U.S. 

Polyphenylene oxide (PPO) thermoplastic polymer with good electrical and mechanical properties and excellent dimensional stability over a wide range of temperatures. Uses include medical equipment, electronic components, hot water controls, etc. 

Polypyrrole and polythiophene, both first described in 1963 as electrically conducting materials [la], experienced a renaissance when Diaz and Street gave new attention to the electrochemical oxidation of pyrrole [21], and Gamier to the polythiphene field transistor. Polyphenylene vinylene, polyaniline, polyphenylene sulfide, polycarbazole, polyindole, polypyrene and polyene fulvene are just a few of the large number of electrically conducting polymers with specific properties and interest [22]. 

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