Electrical properties of polyphenylene

Electrical properties of polyphenylene sulfide compounds are summarized in Table III. The dielectric constant of 3.1 is low in comparison with many other plastic materials. Similarly, the dissipation factor is very low. Dielectric strength ranges from about 500-600 volts per mil for the various compounds these values are quite high. Thus, both... 

Table III. Electrical Properties of Polyphenylene Sulfide Compounds...

The electric properties of polyphenylene sulfide and the ability to injection mold very small parts with great precision have led to the use of a variety of connectors, coil forms, etc., in the electronics industry. For example, a pin cushion connector coil terminal support used in color television is now being volume produced from PPS in a multiple unit. 

The electrical properties of the three polyphenylene sulfide compounds are given In Table IV. The 40% glass-filled PPS Is the best Insulator as Indicated by the dielectric constant of 3.8. 

Table V Indicates the good retention of electrical properties exhibited by the 40% glass-filled PPS at temperatures up to 147°C. In addition, exposure of test specimens to 50 per cent relative humidity for 5 days did not cause any appreciable change In either dielectric constant or dissipation factor. Thus, environmental factors do not have much effect upon the electrical behavior of polyphenylene sulfide resins.

A variety of low-dielectric, low-loss resin systems are available for high-speed circuit apph-cations. These include polytetrafluoroethylene (FTFE or Teflon ), cyanate ester, epoxy blends, and allylated polyphenylene ether (APPE). Likewise, a few different reinforcements and fillers are available that can be used to modify the electrical properties of the base material. Although E-glass is stm the most commonly used fiberglass reinforcement, it should be noted that others are available. In addition, inorganic fillers are sometimes used to modify electrical properties as well. Table 9.6 provides electrical property data on some of the available fiberglass materials. Table 9.7 provides data on some of the base material composites available. 

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

An extensive review of the synthesis of rc-conjugated polymers is presented using a tutorial approach to provide an introduction to the field intended for the undergraduate student and the experienced chemist alike. The many synthetic methodologies that have been used for the synthesis of conjugated polymers are outlined for each class of polymers with a focus on research from the 1990s. The effect of structure on electrical properties is detailed. Specific systems reviewed include the polyacetylenes, polyanilines, polypyrroles, polythiophenes, poly(arylene vinylenes), and polyphenylenes. 

Polymer nanotubes composites are now extensively studied. Indeed, one may associate the properties of the polymer with those of nanotubes. This is the case of the mechanical reinforcement of standard polymer for example, but also one can take advantage of the specific electronic properties of the nanotubes. Therefore, we prepared composites with either saturated polymers like polymethylmethacrylate and MWNTs [27]. The electrical conductivity of these compounds as a function of the nanotube content exhibits for example a very low percolation threshold, (a few % in mass) and therefore they can be used as conducting and transparent layers in electronic devices such as Light Emitting Diodes (LEDs). Another type of composite that we have studied is based on the use of a conjugated polymer, polyphenylene-vinylene (PPV) known for its photoluminescence properties and SWNTs. We prepared this composite by mixing SWNTs to the precursor polymer of PPV. The conversion into PPV was subsequently performed by a thermal treatment at 300°C under dynamical vacuum [28],... 

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. 

Furthermore, the electrical properties can be adjusted by varying the matrix polymer and the filler distribution. Since the material concept allows for the use of almost any polymer matrix, the required material properties, for instance a high temperature resistance, can be provided by the use of polyphenylene sulfide (PPS) as a matrix polymer. The morphological structure, and thus the measured conductivity over the thickness, depend on the ratio of the melt temperatures and viscosities of both the polymer and metal alloy, whereas the passage conductivity is at a similarly high level of >4x10 S/m. 

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. 

The excellent electrical insulation property of E-glass has found many applications in this field. Fabrics made of textile glass yarn is the backbone of the printed circuit board of the modern electronic industry. Polybutene terephthalate, polyphenylene sulfide, and liquid crystal polymer reinforced with chopped glass fiber are also widely molded into electronic components (23). 

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. 

Another requirement of a polymer for use in critical applications might be a combination of excellent continuous or maximum operating temperatme (see Table 4.6) and good electrical properties. It is seen in Table 5.8 that polyether ketone, polyphenylene sulfide, and polytetrafluoroethylene all meet the requirements. 

Blown films can be produced from these high molecular weight resins on conventional equipment. These films are transparent and amber as produced. If films are biaxially oriented, this transparency is retained on annealing. At a blow-up ratio of 3.0, the tensile strength and elongations are essentially the same in both the machine and transverse directions (Table V). Electrical properties are typical for polyphenylene sulfide resins. 

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. 

The search is always on for new, more cost effective alloys and, in Japan, Sumitomo Chemical and Yamagata University have developed a unique plastic alloy which is environmentally friendly, lower priced, has better heat resistance and better electrical properties than comparable products currently being marketed. The new alloy has been derived from the combination of polyphenylene (PPE) with an ethylene-epoxy copolymer. Furthermore, the compound s structure has been controlled to improve its processability. Possible uses include insulation films and housings of mobile phones and other electronic appliances. 

The Ryton polyphenylene sulphide compounds are formulated for the encapsulation of semiconductors and discrete components and are particularly suited to this application because of their excellent thermal stability, resistance to chemical environments, flame retardancy and good electrical properties over a wide temperature range. In order to be suitable for the encapsulation of microcircuits and transistors the material must have good flow during moulding, good dimensional stability, low levels of impurities and low moisture absorption characteristics. 

Polyphenylene sulphides are a range of compounds offering a unique combination of mouldability, good electrical properties, solvent and... 

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. 

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