Low and Cryogenic Temperatures

ASTM D2557-98 Standard test method for strength properties of adhesives in shear by tension loading in the temperature range from -267.8 to-55°C. 

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Polyurethane, PVC, and extruded polystyrene provide the bulk of the cellular plastics used for low and cryogenic temperature appHcations. In some cases, eg, the insulation of Hquid hydrogen tanks on space systems, foams have been reinforced with continuous glass fibers throughout the matrix. This improves strength without affecting thermal performance significantly. 

Sims, M. G. (1972) Bibliography on Low and Cryogenic Temperature Properties of Adhesives, 1965-72, Library Bibliography No. 332, Royal Aircraft Establishment, Farnborough, UK. 

The chemical and physical properties of each of these window materials vary widely. For example, polyimide is flexible, semitransparent, and chemically inert, but it has an upper working temperature of 673 K (for information about the properties of Kapton see http //www2.dupont. com/Kapton/en US / assets / downloads / pdf/ summaryofprop.pdf). Beryllium is stiff, has a low density, high thermal conductivity, and a moderate coefficient of thermal expansion it can be machined and is very stable mechanically and thermally. It also retains useful properties at both elevated and cryogenic temperatures. However, it does require a few safety-related handling requirements that are well documented (for detailed environmental safety and health information about beryllium see http //www.brushwellman.com). Nonetheless, as is stated in the Brush Wellman literature (for detailed environmental safety and health information about beryllium see http //www.brushwellman.com), "handling beryllium in solid form poses no special health risk."... 

This chapter describes and illustrates the major types of containers used to transport and store compressed gases, including those liquefied at very low or cryogenic temperatures. To keep pace with developments in the industry, CGA, through its technical committees, continually reviews and recommends changes to existing container specifications promulgated by the U.S. Department of Transportation (DOT) or Transport Canada (TC). Moreover, new specifications for compressed gas containers are also proposed from time to time. 

A second issue which has received much attention is the unusual temperature dependence of the electron transfer reactions in the RC. The observed time constants for P P BPhL and for P RPh -> P Qa found to be -- 3 ps and —200 ps, respectively, at room temperature and —1 and —100 ps, respectively, at cryogenic temperatures [11,16,17]. An apparent increase in the rate of electron transfer with decreasing temperature also is observed for the P Qa charge recombination reaction which occurs with —120 and —30 ms time constants at room and cryogenic temperatures, respectively [18,19]. These findings of non-Arrhenius behavior typically have been analyzed in terms of the coupling of low frequency vibrational modes of the pigment-protein complex to electron transfer (see e.g. 16,17,20,21). 

This copolymer has useful properties from cryogenic temperatures to 180°C. Its dielectric constant is low and stable over a broad temperature and frequency range. 

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