Service-temperature range

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. 

Plain Carbon and Low Alloy Steels. For the purposes herein plain carbon and low alloy steels include those containing up to 10% chromium and 1.5% molybdenum, plus small amounts of other alloying elements. These steels are generally cheaper and easier to fabricate than the more highly alloyed steels, and are the most widely used class of alloys within their serviceable temperature range. Figure 7 shows relaxation strengths of these steels and some nickel-base alloys at elevated temperatures (34). 

By block copolymerisation so that one component of the block copolymer has a Tg well below the expected service temperature range (e.g polypropylene with small blocks of polyethylene or preferably polypropylene with small amorphous blocks of ethylene-propylene copolymer). 

By the use of a polymer which has effective transitions at or below the expected service temperature range and which is able to respond to stress by extensive deformation (e.g. polycarbonates). 

A VDF unit also follows FIFP m the structurally much more complex terpo-lymers [30] Dipolymers contain 60 wt % VDF (66% F) and terpolymers contain 33-50 wt % VDF (66-69 5% F) and generally less than 28 wt % TFE Molecular weights range from 1 5 x 10 to 10 Their respective continuous service temperature ranges are -18 to 210 °C and -12 to 230 °C Dipolymer vulcanizates retam over 50% of their tensile strength for more than 1 year at 200 °C or for 2 months at 260 C... 

Yu J.M., Dubios P., and Jerome R., Synthesis and properties of polypsobomylmethacrylate (IBMA)-b-butadiene (BD)-b-IBMA] copolymers New thermoplastic elastomers of a large service temperature range. Macromolecules, 29, 7316, 1996. 

It is difficult to make a comparison because each material can be sensitive to different chemicals but, generally, within the service temperatures range, the chemical resistance increases with the amount of fluorine, or halogen total for PCTFE and ECTFE. 

The polyimide foams are flexible and have a very low density (7 kg/m ), associated with good fire behaviour, a broad service temperature range and good soundproofing and thermal insulation qualities. These materials are sensitive to diluted strong bases, concentrated salts and acids. Other foams have densities varying from 15-250 kg/m. ... 

Electrolytes are ubiquitous and indispensable in all electrochemical devices, and their basic function is independent of the much diversified chemistries and applications of these devices. In this sense, the role of electrolytes in electrolytic cells, capacitors, fuel cells, or batteries would remain the same to serve as the medium for the transfer of charges, which are in the form of ions, between a pair of electrodes. The vast majority of the electrolytes are electrolytic solution-types that consist of salts (also called electrolyte solutes ) dissolved in solvents, either water (aqueous) or organic molecules (nonaqueous), and are in a liquid state in the service-temperature range. [Although nonaqueous has been used overwhelmingly in the literature, aprotic would be a more precise term. Either anhydrous ammonia or ethanol qualifies as a nonaqueous solvent but is unstable with lithium because of the active protons. Nevertheless, this review will conform to the convention and use nonaqueous in place of aprotic .]... 

As with most nonpolar hydrocarbon-intense polymers, bitumens exhibit good resistance to attack by inorganic salts and weak acids. They are dark, generally brown to black, and their color is difficult to mask with pigments. They are thermoplastic materials with a narrow service temperature range unless modified with fibrous fillers and/or synthetic resins. They are abundant materials that are relatively inexpensive, thus their use in many bulk applications. 

Service Temperature range Pressure range Material class Ref. note... 

Maferials fhaf already are pressure-sensifive adhesives, buf can be modified by radiation (UV or EB) to infroduce or increase cross-linking, which increases their adhesive properties, shear value, peel strength, service temperature range, and solvent resistance... 

The description of the physical properties of fluoroelastomers is necessarily less precise than that of fluoroplastics because of the major effect of adding curatives and fillers to achieve useful cross-linked materials of a given hardness and specific mechanical properties Generally, two parameters are varied increasing cross-link density increases modulus and decreases elongation, and raising filler levels increases hardness and decreases solvent swell because of the decreased volume fraction of the elastomer In addition to these two major vanables, the major determinants of vulcanizate behavior are the chemical and thermal stabilities of its cross-links The selection of elastomer, of course, places limits on the overall resistance to fluids and chemicals and on its service temperature range... 

FIGURE 5.1 Useful service temperature ranges for commercial fluoroelastomers. (From Scheirs, J., in Modern Fluoropolymers, Scheirs, J., Ed., John Wiley Sons, New York, 1997. With permission.)... 

Some of these plastics often compete for the same applications. Strength, modulus of elasticity, impact strength, and other properties vary greatly with type, degree of crystallinity, and their preparations that result in different densities. Their stress-crack resistance and useful service temperature ranges may also vary with type of polyolefin, their crystalline structure, etc. 

FZ elastomer offers a broad service temperature range, namely, from -65°C to 175°C (-85°F to 347°F) [110], excellent flex fatigue resistance, damping properties, and resistance to chemicals and fluids. 

Sixty percent alumina brick seems to perform best in the 2000°F to 2400°F service temperature range. These bricks should also be high fired, low porosity and low in the impurities mentioned above. 

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