Tape, magnetic

Fig. 3. An overview of atomistic mechanisms involved in electroceramic components and the corresponding uses (a) ferroelectric domains capacitors and piezoelectrics, PTC thermistors (b) electronic conduction NTC thermistor (c) insulators and substrates (d) surface conduction humidity sensors (e) ferrimagnetic domains ferrite hard and soft magnets, magnetic tape (f) metal—semiconductor transition critical temperature NTC thermistor (g) ionic conduction gas sensors and batteries and (h) grain boundary phenomena varistors, boundary layer capacitors, PTC thermistors.

Tensile properties of importance include the modulus, yields, (strength at 5% elongation), and ultimate break strength. Since in many uses the essential function of the film may be destroyed if it stretches under use, the yield and values are more critical than the ultimate strength. This is tme, for example, where film is used as the base for magnetic tape or microfilm information storage. In some cases, the tensile properties at temperatures other than standard are critical. Thus if films are to be coated and dried in hot air ovens, the yield at 150°C or higher may be critical. 

In conventional tenter orientation, the sequence of steps is as described above (MD—TD). In some cases it is advantageous to reverse the draw order (TD—MD) or to use multiple draw steps, eg, MD—TD—MD. These other techniques are used to produce "tensilized" films, where the MD tensile properties are enhanced by further stretching. The films are generally unbalanced in properties and in extreme cases may be fibrillated to give fiber-like elements for special textile appHcations. Tensilized poly(ethylene terephthalate) is a common substrate for audio and video magnetic tape and thermal transfer tape. 

The National Chemical Laboratory for Industry (NCLl), Japan, has developed an integrated Spectral Database System (SDBS) which is available to users in Japan. AU spectra were deterrnined at NCLl under controUed conditions and are available on a PC/CD-ROM or magnetic tape. The system has both H-nmr (6000 compounds) and C-nmr spectra (5700 compounds), along with searching software. NCLl has also developed an integrated C— H-nmr system that can be used for two-dimensional data elucidation (70,71). 

Mass Spectroscopy. A coUection of 125,000 spectra is maintained at Cornell University and is avaUable from John WUey Sons, Inc. (New York) on CD-ROM or magnetic tape. The spectra can be evaluated using a quaHty index algorithm (63,76). Software for use with the magnetic tape version to match unknowns is distributed by Cornell (77). The coUection contains aU avaUable spectral information, including isotopicaUy labeled derivatives, partial spectra, and multiple spectra of a single compound. 

The most important mass memories use magnetic media in the form of magnetic tapes or disks (floppy disk and hard disk). Laser addressed optical mass memories are of increasing commercial importance. 

Erasable optical disk (EOD) systems, on the other hand, are challenging classic magnetic media in some areas of appHcation, primarily magnetic tape and the hard disk, but mostly optical media complement magnetic media. 

MEK is also used iu solvent-based adhesives, iu printing ink formulations, as a solvent iu magnetic tape manufacture, and is the most common solvent used iu dewaxing lubricating oils. Of all these appHcations only an increasing consumption of magnetic tapes is likely to grow ia methyl ethyl ketone use. 

Electrically Functional. Refractory coatings are used in semiconductor devices, capacitors, resistors, magnetic tape, disk memories, superconductors, solar ceUs, and diffusion barriers to impurity contamination from the substrate to the active layer. 

The exceUent adhesion to primed films of polyester combined with good dielectric properties and good surface properties makes the vinyhdene chloride copolymers very suitable as binders for iron oxide pigmented coatings for magnetic tapes (168—170). They perform very weU in audio, video, and computer tapes. 

Includes paints and poHshes, antiknock and other compounds, soldering and/or welding, electrical and electronic products, mechanical products, magnetic tape, small packages, industrial diamonds, and drilling mud. 

Mag netic Tapes. Chromium dioxide, Cr02, is used as a ferromagnetic material in high fidelity magnetic tapes (qv). Chromium dioxide has several technical advantages over the magnetic iron oxides generally used (58,246). 

Uses. Approximately 70% of the U.S. production is used to make poly(tetramethylene ether glycol) [25190-06-1] (PTMEG), also known as poly-THE, which is used in the production of urethane elastomers, polyurethane fibers (ether-based spandex), and copolyester—ether elastomers. PTMEG is also the fastest growing use (see PoLYETPiERS, TETRAHYDROFURAn). The remaining production is used as a solvent for the manufacture of poly(vinyl chloride) cements and coating, precision magnetic tape, a reaction solvent in the production of pharmaceuticals, and other miscellaneous uses. 

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