Aging characteristics

Steam digestion of siHcone mbber produces a siHcone reclaim, used to reduce the cost of siHcone compounds. It has been widely used by siHcone automobile ignition systems. The resulting compounds have exceUent aging characteristics and stUl possess outstanding electrical properties (16). 

Asphalt (bitumen) also occurs in various oil sand (also called tar sand) deposits which occur widely scattered through the world (17) and the bitumen is available by means of various extraction technologies. A review of the properties and character of the bitumen (18) suggests that, when used as an asphaltic binder, the bitumen compares favorably with specification-grade petroleum asphalts and may have superior aging characteristics and produce more water-resistant paving mixtures than the typical petroleum asphalts. 

Co-distillation leads to long period of time under heat resulting in exceeding the isothermal aging characteristics for a thermally unstable material which leads to thermal decomposition and overpressure of the vessel. 

Evaluate isothermal aging characteristics of thermally unstable components at the maximum expected utility temperature... 

Insulation systems were first classified according to the material used, and permissible temperatures were established based on the thermal aging characteristics of these materials. For example. Class B insulation was defined as inorganic materials such as mica and glass with organic binders 130°C was the allowable maximum operating temperature. The present definition of insulation system Class B stipulates that the system be proven. . by experience or accepted tests. .. to have adequate life expectancy at its rated temperature, such life expectancy to equal or... 

ABS materials are widely used as impact modifiers but cause opacity and have only moderate aging characteristics. Many grades show severe stress-whitening, generally a disadvantage, but a phenomenon positively employed in labelling tapes such as Dymotape. 

Heat aging characteristics may be improved by the addition of a few per cent of ferric oxide and barium zirconate to name but two materials mentioned in the literature. 

PPG would allow more metal at the expense of the oxidizer to further energize the composition. In addition, HTPB is frequently preferred over PPG because of its superior mechanical properties, better aging characteristics, and lower glass-transition temperature (Tg). The latter is especially desirable because at low temperature, the higher strain rates produced by motor ignition decrease the elongation of the composite rather markedly. 

These tolerances do not include allowance for aging characteristics of material. 

The resins as a class are colorl.odorl, non-toxic and have v good aging characteristics. The initial mp (or glass transition temp) is 28 (Ref 4). The polymer of 24,500 mw is sol in chlf, benz, py, dicxane and acet msoi in carbon disulfide, carbon tetrachloride, cyclohexane, hexane,etc... 

Recipes for metal oxide vulcanization are given in Table 14.19. In one case, calcium stearate was used instead of magnesium oxide to obtain better aging characteristic [32]. 

The G types do not require further acceleration during cure, but exhibit slightly inferior ageing characteristics. Resilience and tack are generally better than with the W types. 

Tsapatsis, M. and G. Gavalas, Structure and aging characteristics of H2-permselective Si02-Vycor membranes, /. Membr. Sci., 87, 281, 1994. 

ISO 2440 1997 Flexible and rigid cellular polymeric materials - Accelerated ageing tests ISO 6914 2004 Rubber, vulcanized - Determination of ageing characteristics by measurement of stress at a given elongation... 

Uncured poly(GlyN) prepolymer exhibits good chemical stability and has a satisfactory shelf-life. However, the ageing characteristics of isocyanates cured PU rubbers are unsatisfactory contrary to (NiMMO) rubbers which have good ageing characteristics. Long term ageing trials have shown that the cured... 

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