Rubbers dielectric constant

Uses Rubber accelerator solvent in fiber and plastic industry rocket fuels lubricants condensers to increase dielectric constant industrial solvent antioxidant nematocide softener of copolymers research chemical plasticizer in acrylonitrile polymers inhibit nitrification in soil chemical intermediate for 1,1-dimethylhydrazine. 

Rubber Shore A Hardness Specific gravity (25° C) Refractive index 20° C) Dielectric constant (1 kcxsec, 25° C) Tg, <°C) Melting Temp. °C Tensile strength (psi) % Elongation... 

Fig. 15. Temperature dependence on the dielectric constant of various polymers at 75cps. (O) Polyhexamethyl-ene-adipamide 0.005 in ( ) Silicone-bonded samica 0.004 in (O) Cellulose 0.005 in ( ) Polyimide 0.0048 in ( ) Polyethylene 0.005 in ( ) Rubber hydrochloride 0.002 in (A) Polyethylene terephthalate (Melinex) 0.005 in (A) Polyethylene terephthalate (Mylar) 0.002 in (V) Polypropylene 0.010 in (A) Polytetrafluoroethylene 0.0075 in (X) Polystyrene 0.005 in (+) Aromatic polyamide 0.0027 in (1 in = 2.54 cm)...

Methyl silicone rubber also shares the excellent electrical properties of the resins and oil. A molded sample with silica filler had a dielectric constant of 3.0 at room temperature over a range of 60 to 1010 cycles. The loss factor remains at 0.004 from 60 to 107 cycles and then rises rapidly to 0.037 at 109 cycles and 0.055 at 1010 cycles. At 102° C. the values remain the same except for a small decrease in dielectric constant (caused by a decrease in density) and a slight indication of enhanced d-c conductivity. The rubber does not seem to be affected by ozone. 

Polymers have unique versatility for many packaging applications in that their mechanical properties can be tailored, giving materials ranging from rubber-like gels with dramatic changes in modulus with temperature, to hard solids with almost no changes at all. Moreover, electrical properties can be varied to achieve, within limits, desired values of dielectric constant, low ionic conductivity, etc. Key concerns today often center on the ability to achieve simultaneously the desired mechanical and electrical properties, a difficult task. The ability to tailor the coefficient of thermal expansion, CTE (also often abbreviated TCE) to match that of the substrate or of other components is a subject of considerable interest. 

Most of the research effort on the ionomers has been devoted to only a small number of materials, notably the ethylenes the styrenes, the rubbers(9)5 and those based on poly(tetra-fluoroethylene), the last of which is the subject of the present volume. As a result of these extensive investigations, it has become clear that the reason for the dramatic effects which are obsverved on ion incorporation is, not unexpectedly, the aggregation of ionic groups in media of low dielectric constant. Small angle X-ray and neutron scattering, backed up by a wide range of other techniques, have demonstrated clearly the existence of ionic... 

Organo-silica compounds are widely used in a range of industries such as printing, oil production, and mining as lubricants and polishing compounds. They also find domestic use in silicon rubber and aerosol sprays because of their special physical properties, such as viscosity and dielectric constant. These compounds are also recognized as poisons/inhibitors in different catalytic processes, such as in atmospheric scrubbers, automobile exhausts, flammable gas... 

MAJOR USES Used in the production of lubricants, plastics, rocket fuel, fibers, nema-tocide and rubber antioxidant increase dielectric constant inhibition of nitrification in soil. 

ORIGIN/INDUSTRY SOURCES/USES used as a solvent in fiber, plastics industry, lubricants condensers to increase dielectric constant nematocide softener for copolymers formerly in production of rocket fuels research chemical chemical intermediate for 1,1-dimethylhydrazine rubber accelerator inhibition of nitrification in soil plasticizer for acryloni-tnle polymers preparation of thiocarbonyl fluoride polymers antioxidant... 

Polymers containing hydrolysable groups or which have hydrolysable groups introduced by oxidation are susceptible to water attack. Hydrolyzable groups such as esters, amides, nitriles, acetals, and certain ketones can react with water and cause deterioration of the polymer. The dielectric constant, power factor, insulation resistance, and water absorption are most affected by hydrolysis. For polyesters, polyamides, cellulose, and cellulose either and esters, the hydrolysable groups are weak links in the chain, and hydrolysis of such polymers can cause serious loss of strength. A summary of water absorption characteristics of common plastic and rubbers is presented in Table 1.15. 

Jung et al. have developed a synthetic elastomer composed of acrylonitrile butadiene rubber copolymer [211, 212]. The properties of the copolymer can be tuned by changing its composition. Reported data for dielectric constant, elastic modulus, and strain relaxation are promising (see Table 1.2). The synthetic elastomer provides some improvement over VHB and some silicone hlms under certain conditions however, the tests were limited to low prestrain (60% radial), where the performance of VHB hlms is poor. 

Electrical Properties Nitrile rubbers do not have good electrical insulating properties, value s of the order of 10 ° ohm/cm being typical. Power factor and dielectric constant (800 cycles) are 0.03 and approximately 15, respectively. These properties can be used to advantage in applications such as belts and rollers on textile spinning machinery where with suitable compounding the resistivity is reduced to the point where build up of static electricity is prevented in service. 

The value of is frequently considered unity for air. If the dielectric constant of a vacuum is considered unity the value for air at 0°C and 760 mm pressure is 1.000567. Weast RC (ed) (1971) Handbook of chemistry and physics, 52nd edn. The Chemical Rubber Co., Boca Raton, FL. 

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. 

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