( 7 ) Glaser, hl. A , , Product Eng., 21, 109-11 (February 1950). (8) Goodwin, J. T., *Jr., and Hunter, 11.J. (Dow Coriiing Corp.), U. S. Patent 2,584,340 (Feb. 5, 1952). (9) Ibid., 2,584,344. (10) Ibid.,2,589,243 (March 18, 1952). (11) Hedlund, R. C., Finish,10, No. 1 0 , 4 5 4 107-8 (1953). (12) Kress, B. H., and Hoppens, H. A., Dig. Federation P a i n t & Varnish Production Clubs, No. 333, 659-99 (1952). (13) Libbey-Owens-Ford Glass Co., Brit. Patent 694,716 (July 29, 1953). (14) MeGregor, R. R., “Silicones and Their TJses,” 3lcGraw-Hil1, New York, 1954. (15) Miller, E., and Glaser, 11.A , , Prod7~ctEng,,24, 167-74 (March 1953). (16) Murphy, C. AI., Saunders, C. E., and Smith, D. C., IND.ENG. CHEM.,42, 2462-8 (1950). (17) Ofic. Dig. Federation, Paint & T‘amish Pvoduetion Clubs, N o . 250, 4 2 4 4 ’ (1945). (18) Ibid., 262, 534-9 (1946).
(19) lbid.,334, 749-54 (1952). (20) Patterson, Ofic. Dig. Federation Paint & Varnisli Production C h b S , NO.258, 281-90, 439-42 (1946). (21) Rochow, E. G . , “-4n Introduction to the Chemistry of the Silicones,” John Wiley, Sew York, 1961. (22) Sage, C. 31. (General Electric Co.), U. S. Patent 2,523,065 (Sept. 19, 1950).
(23) Shur, E. G., Ofic.Dig.E’eclcration Paint & Varnish Production Clubs, NO.323, 887-77 (1951). (24) Tyler, L. J., Dow-Corning Corp., Midland, Mich., private coni-
municat,ion, 1954. (25) Warrick. E. L., Hunter, 11. J., and Barry, A , J., IND. ESG. CHEM., 4 4 , 2 1 9 6 2 0 2 (1952). (26) Williams, R.A., Luta, I. H., Hayne, W. H., Louisville Institute of Industrial Research, Louisville, Ky., “Development of
High Temperature Heat Resistant Coatings.” RECEIVED for review March 2 7 , 1R54.
ACCEPTEDScptembor 0 , 1964.
Compounding rinciples of Silicone Rubbers C . W. PFEIFER General Electric Co., Waterford, \-. Y .
Silicone rubber gums provide the rubber industrj with new polymeric materiale useful for compounding in rubbers, w-hich extend the application of elastomeric materials. Rubbers can be made that are flexible below -100’ F. and that will withstand service as high as 600’ F. Good electrical properties w-ith excellent resistance to ozone are obtainable. Some principles involved in the designing of a general purpose group, a low compression set group, and an extreme low temperature group of silicone compounds are described. These formulations and data are expected to be useful to many rubber compounders who are assuming the task of silicone rubber gum compounding. HE importance of the engineering possibilities of silicone rubber was recognized m early as 1942; indeed, the first United States Patent covering met,hylsiloxane elastomers was applied for in 1944 (1). Production of the silicone rubber parts for the first t,wo military applications, gaskets for turbosuperchargers and gasket,s for searchlights, was accomplished by research laboratory personnel. Shortly after the war, the applications for silicone rubber began to grow; today the list of companies fabricating silicone rubber contains over 100 names, and new ones are being added steadily. Since the industry is relatively new, technical progress is being made rapidly; the silicone rubber industry is a fine exainple of progress in the competitive enterprise system. Progress is being made in the development of improved gums, reinforcing fillers, and compounding and fabricating techniques. Silicone rubber has some unique basic properties which are responsible for its place in the industrial picture. Rubbers can be made that will withstand temperatures as high as 600’ F. without serious deterioration; rubbers can also be made t h a t are flexible a,t - 130’ F. The oxygen, ozone, and weathering rcsistances are cxtremely good. The basic property of inertness makes i t useful for many room temperature applications such as surgical rubber and pharmaceutherange is expanding. Shipboard cables must be rugged to withstand severe installation handling and must possess the maximum degree of reliability of operation throughout a long life under difficult environmental conditions involving exposure to weather, fresh and salt water, oil, vibration, abrasion, high shock impact, and a wide range of ambient temperat,ure. And this must be accomplished with a reasonable faccor of safety by cables of minimum size and m i g h t . I n commercial applications generally the size and weight of the cable installation may not bc so significant. The rapid growth of the shipboard electrical plant and distribution system, including electronics, made it imperative that thc size of cables and wireways be reduced and not allowed t o expand. Vessels that were built during World War I1 were xired with Navy-type heat and flame resistant armored (Type HF,\) cables in which the primary insulation mas varnished cambric or synthetic resin reinforced with a cushioning fire wall of asbcst’os. These designs have given entirely satisfact,ory seruicc, but it was hardly practicable to alter the construction of these cables during a large shipbuilding program, so a long-range development was undertaken. A project was established in IO42
INDUSTRIAL AND ENGINEERING CHEMISTRY
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