Showing papers in "Industrial & Engineering Chemistry in 1967"

Cleaning by surface displacement of water and oils

Abstract: An effective and economical surface-chemical displacement of water and (or) oily contamination on solid surfaces can be accomplished with certain classes of organic compounds and emulsions made from them. The essential displacement mechanism is the creation of maintenance of a surface tension gradient in the free surface of any liquid coating the solid. Such a gradient can be maintained with a drop of a spreading agent which escapes from the liquid surface by solution or evaporation after a few cm. Of travel away from the point of application. The resulting movement of the surface monolayer of agent carries along the liquid coating by a viscous-drag process. Permanent (irreversible) displacement of the liquid coating takes places only when the displacing agent (or a specific surfaceactive component in it) is able to adsorb strongly on the solid surface to form an insoluble, low-energy, surface film. Water displacers include aliphatic alcohols from propyl to hexyl, methyl amyl ketone, acetylacteone, amyl acetate, Cellosolve acetate, ethyl acetoacetate, butyl or propyl lactate, ethyl or methyl carbonate, and the Cellosolves. Effective and economical oil-displacing agents for removing many common types of oily films are readily prepared from emulsions in water of an organic liquid which has (1) a significantly high solubility in that oil. A variety of successful applications to salvaging valuable and complex military equipment, including motors, generators, switch gear, radio receivers and transmitters, radars, and various mechanical devices are described, and suitable techniques and procedures for such operations are summarized. Numerous applications are indicated for routine maintenance cleaning or salvaging and re storing to useful service for a wide variety of types of mechanical, electrical, and electronic equipment after flooding. Work is summarized in developing: (a) cleaning emulsions for rapidly and economically removing oily coatings from mechanical, electric, or electronic equipment, (b) water-displacing compounds that rapidly displace water from surfaces of equipment, parts, and crevices accessible to a liquid spray and thus accelerate greatly the drying process, (c) aggressive chemical cleaners to remove corrosion products not otherwise removed, and (d) special techniques for facilitating the chemi cal salvaging process.

The thermal degradation of epoxide resins

Abstract: ON REVIEWING THE RELEVANT LITERATURE, IT BECOMES APPARENT THAT DESPITE THE CONSIDERABLE AMOUNT OF WORK THAT HAS BEEN DONE IN THIS FIELD THERE IS STILL RELATIVELY LITTLE KNOWN ABOUT THE MECHANISM OF THE THERMAL DEGRADATION OF EPOXY RESINS. ALTHOUGH IT HAS BEEN ESTABLISHED THAT THE DEGRADATION PROCEEDS (PARTLY AT LEAST) THROUGH A FREE RADICAL MECHANISM, IT IS IMPOSSIBLE TO STATE WITH ANY CERTAINTY THE REACTIONS WHICH LEAD TO THE FORMATION OF PARTICULAR BREAKDOWN PRODUCTS. IN FURTHER STUDIES ON EPOXIDE DEGRADATION THE FOLLOWING POINTS SHOULD BE CONSIDERED: (1) SAMPLE GEOMETRY AND PHYSICAL STATE OF THE MATERIAL MAY INFLUENCE THE COURSE OF DEGRADATION THROUGH SECONDARY REACTIONS, TEMPERATURE GRADIENTS, AND DIFFUSION PHENOMEN. (2) THE RESULTS OBTAINED IN WORK OF THIS KIND MAY, TO SOME EXTENT, BE A FUNCTION OF THE METHODS OF DEGRADATION AND ANALYSIS. TOO MUCH RELIANCE SHOULD NOT THEREFORE BE PLACED ON DATA OBTAINED FROM ANY ONE METHOD. (3) IMPURITIES AND ADDITIVES IN COMMERCIALLY AVAILABLE EPOXIDE RESINS MAY INFLUENCE THEIR THERMAL STABILITY. IT IS THEREFORE DESIRABLE TO WORK WITH CAREFULLY CHARACTERIZED EPOXIDE AND HARDENERS TO ESTABLISH THE FUNDAMENTAL DEGRADATION REACTIONS. /AUTHOR/