Glasses electrical properties

E-glass Family of glasses with low alkali content, usually under 2.0 percent, most suitable for use in electrical-grade laminates and glasses. Electrical properties remain more stable with these glasses due to the low alkali content. Also called electrical-grade glasses. 

Electrical. Glasses are used in the electrical and electronic industries as insulators, lamp envelopes, cathode ray tubes, and encapsulators and protectors for microcircuit components, etc. Besides their abiUty to seal to metals and other glasses and to hold a vacuum and resist chemical attack, their electrical properties can be tailored to meet a wide range of needs. Generally, a glass has a high electrical resistivity, a high resistance to dielectric breakdown, and a low power factor and dielectric loss. 

Oxides. Although not widespread commercially, glass-ceramics consisting of various oxide crystals in a matrix of siUceous residual glass offer properties not available with mote common siUcate crystals. In particular, glass-ceramics based on spinels and perovskites can be quite refractory and can yield useful optical and electrical properties. 

Relatively few processible polyimides, particularly at a reasonable cost and iu rehable supply, are available commercially. Users of polyimides may have to produce iutractable polyimides by themselves in situ according to methods discussed earlier, or synthesize polyimides of unique compositions iu order to meet property requirements such as thermal and thermoxidative stabilities, mechanical and electrical properties, physical properties such as glass-transition temperature, crystalline melting temperature, density, solubility, optical properties, etc. It is, therefore, essential to thoroughly understand the stmcture—property relationships of polyimide systems, and excellent review articles are available (1—5,92). 

Electrical property Ryton PPS R-4XT, 40% glass-fiUed Ryton PPS R-7, glas s—rnineral-filled... 

Plasma processing technologies ate used for surface treatments and coatings for plastics, elastomers, glasses, metals, ceramics, etc. Such treatments provide better wear characteristics, thermal stability, color, controlled electrical properties, lubricity, abrasion resistance, barrier properties, adhesion promotion, wettability, blood compatibility, and controlled light transmissivity. 

A number of reviews have appeared covering the various aspects of borate glasses. The stmcture, physical properties, thermochemistry, reactions, phase equihbria, and electrical properties of alkah borate melts and glasses have been presented (73). The apphcation of x-ray diffraction, nmr, Raman scattering, in spectroscopy, and esr to stmctural analysis is available (26). Phase-equihbrium diagrams for a large number of anhydrous borate systems are included in a compilation (145), and thermochemical data on the anhydrous alkah metal borates have been compiled (17). 

Since the incorporation of plasticisers into a polymer compound brings about a reduction in glass temperature they will also have an effect on the electrical properties. Plasticised PVC with a glass temperature below that of the testing temperature will have a much higher dielectric constant than unplasticised PVC at the same temperature (Figure 6.6). 

The first commercial applications of polypyromellitimides were as wire enamels, as insulating varnishes and for coating glass-cloth (Pyre.ML, Du Pont). In film form (Kapton) many of the outstanding properties of the polymer may be more fully utilised. These include excellent electrical properties, solvent resistance, flame resistance, outstanding abrasion resistance and exceptional heat resistance. After 1000 hours exposure to air at 300°C the polymer retained 90% of its tensile strength. 

Of particular importance are the electrical properties of the laminates. These are generally superior to P-F and M-F glass-cloth laminates, as may be seen from Table 29.3P... 

The resins known as DAP and DAIP, are cross linked allyl esters of phthalic and rsophthalic acid, respectively. They are notable for rigidity and excellent electrical properties at temperatures up to 4.50" F. Allylic resin-impregnated glass cloth is used in aircraft and missile parl.s. Other... 

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