Electrical properties volume resistivity

Electrical properties Volume resistivity (ohm.cm) Fire behaviour 102 102 l(f l(f... 

Trademarked Kalene, this material is a depolymerized virgin butyl rubber, which is similar to butyl LM rubber. The properties are similar to those of conventional butyl rubber such as the lowest vapor transmission rate of any elastomer, resistance to degradation in high-humidity, high-temperature environments (very Uttle change after 120°C steam for 1(X)0 h), excellent electrical properties (volume resistivity of 5.5 X 10 ohm-cm and a dielectric constant of 3.1), resistance to soil bacteria, excellent weathering, and resistance to chemicals and oxidation. 

In PVC cable fabrication, calcium carbonate is used at loadings of around 70 phr. The choice of calcium carbonate depends on the specifications for cable. Higher qualify cables benefit from the better mechanical properties (tensile strength and elongation) and electrical properties (volume resistivity) offered by ulfrafine coated grades. Cables with lower specification can use uncoated PCC grades. 

Electrica.1 Properties. Because of excellent electrical properties, FEP is a valuable and versatile electrical insulator. Within the recommended service temperature range, PTFE and EEP have identical properties as electrical insulators. Volume resistivity, which is >10 H/cm, remains unchanged even after prolonged soaking in water surface resistivity is >10 H/sq. 

The bulk (or volume)-specific resistance is one of the most useful general electrical properties. Specific resistance is a physical quantity that may vary more than 10 in readily available materials. This unusually wide range of conductivity allows wide variety of electrical applications. Conductive materials, such as copper, have specific resistance values of about 10 fl-cm, whereas good insulators such as polytetrafluoroethylene and LDPE have values of about 10 fl-cm. Specific resistance is calculated from the following equation where R is the resistance in ohms, a is the pellet area in square centimeters, t is the pellet thickness in centimeter, and P is the specific resistance in ohm-centimeter ... 

There are several important electrical properties. Insulation resistance is the resistance of polyurethane to the flow of electricity. The insulation resistance is composed of two main components. The "volume resistivity" is the resistance to flow through the bulk of the material and is a function of the composition of the polymer. The second component is the "surface resistivity,"... 

Standard test method for rubber property-volume resistivity of electrically conductive and antistatic products Specification for electrical properties of conducting and antistatic products made from flexible polymeric material... 

Limiting oxygen ind UL flammability Electrical properties Tracking resistance Comp, tracking resist Surface resistivity Volume resistivity Dissipation factor... 

The volume resistivity of a material is the ratio of the potential gradient parallel to the current in the material to the current density. Insulating materials are generally used to insulate and support components of an electric network from each other and from the ground. Therefore, it is desirable to have the insulation resistance as high as possible, consistent with acceptable mechanical, physical, chemical, and thermal properties. Volume resistivity measurements are designed to isolate the inherent properties responsible for the dc insulating qualities of a plastic material. Resistivities above 10 ohm cm are considered to be insulators those with values of 10 to 10 ohm cm are partial conductors. 

Electrical Properties. The low polarizabiHty of perfluorinated Hquids makes them exceUent insulators. Theh dielectric strengths are about 40 kV (ASTM D877) dissipation factors are about 0.0001 at 1 MH2 dielectric constants are about 1.8 volume resistivities are about 1 x 10 ohm-cm (ASTM D257) (17). 

Electrical Properties. Polytetrafluoroethylene is an excellent electrical insulator because of its mechanical strength and chemical and thermal stabihty as well as excellent electrical properties (Table 6). It does not absorb water and volume resistivity remains unchanged even after prolonged soaking. The dielectric constant remains constant at 2.1 for a temperature range of —40 to 250°C and a frequency range of 5 Hz to 10 GHz. 

Electrical, electronic, and technical appHcations use polycarbonates for a variety of purposes. The woddwide market is about 156,000 t aimuaHy. Because of exceHent electrical properties (dielectric strength, volume resistivity), and resistance to heat and humidity, polycarbonate is used for electrical connectors (qv), telephone network devices, oudet boxes, etc. Polycarbonate had been popular for use in computer and business machine housings, but the use of neat resin has been largely supplanted by blends of polycarbonate with ABS. OveraH, however, the total use of polycarbonate continues to increase. 

Electrical Properties. Generally, deposited thin films have an electrical resistivity that is higher than that of the bulk material. This is often the result of the lower density and high surface-to-volume ratio in the film. In semiconductor films, the electron mobiHty and lifetime can be affected by the point defect concentration, which also affects electromigration. These effects are eliminated by depositing the film at low rates, high temperatures, and under very controUed conditions, such as are found in molecular beam epitaxy and vapor-phase epitaxy. 

Electrical and Mechanical Properties. Electrical properties include dielectric strength, dielectric constant, dissipation factor, and volume resistivity these properties can change with temperature and absorbed water. 

Although these resins have been on the market for a number of years, volumes and appHcations remain low in spite of favorable properties including high temperature resistance, excellent wear and friction properties, good electrical properties, chemical inertness, and inherent nonflammability. ProcessibiHty and price may be the limiting factors. 

The nylons are reasonably good electrical insulators at low temperatures and under conditions of low humidity but the insulation properties deteriorate as humidity and temperature increase. The effects of the amount of absorbed water on the volume resistivity of nylon 66 is shown in Figure 18.15. This effect is even greater with nylon 6 but markedly less with nylon 11. Some typical electrical properties of the nylons are given in Table 18.5. 

The resistance of most plastics to the flow of direct current is very high. Both surface and volume electrical resistivities are important properties for applications of plastics insulating materials. The volume resistivity is the electrical resistance of the material measured in ohms as though the material was a conductor. Insulators will not sustain an indefinitely high voltage as the applied voltage is increased, a point is reached where a drastic decrease in resistance takes place accompanied by a physical breakdown of the insulator. This is known as the dielectric strength, which is the electric potential in volts, which would be necessary to cause the failure of a 1/8-in. thick insulator (Chapter 4, ELEC-TRICAL/ELECTR ONICS PRODUCT). 

There are a number of electrical properties related to electrical resistance (ASTM D-257). These include insulation resistance, volume resistivity, surface resistivity, volume resistance, and surface resistance. 

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