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CONCENTRATES
TECHNOLOGY Slow-release fertilizers may come down sharply in price with a sulfur-coating process developed by Thiokol. The company says it has worked out a system for applying thin coats of polymeric sulfur to several types and shapes of fertilizer particles. The new encapsulant, which Thiokol says is thinner than an earlier sulfur-coating system developed by the Tennessee Valley Authority, would add only 10 to 20% to the price of fertilizer. Coated urea prills would thus sell at about $110 per ton; and other slow-release fertilizers run from $260 to $400 per ton, according to Thiokol. Advantages of slow-release fertilizers include reduced leaching losses in irrigation or high-rainfall areas, reduced crop hazards from high rates of fertilizer application, labor savings from fewer applications, and better growth because of a continuous supply of nutrients. The 10 outstanding achievements of chemical engineering were selected by a panel for the American Institute of Chemical Engineers. The list was disclosed at last week's AIChE meeting in New York City. They are: production of synthetic ammonia; commercial-scale production of antibiotics; establishment of the plastics industry; production of fissionable isotopes; production of petrochemicals; establishment of the synthetic fibers industry; electrolytic production of aluminum; establishment of the synthetic rubber industry; production of chemical fertilizers; and development of highoctane gasoline. A threefold increase in interlaminar shear strength of graphite fibers has been achieved by Thermokinetic Fibers (TKF), a subsidiary of General Technologies Corp. Working under a U.S. Naval Ordnance Laboratory contract, TKF developed a "whiskerizing" process which grows silicon carbide whiskers on a graphite-epoxy fiber, greatly increasing the strength of the bond between the fiber and the matrix of the composite. Typical interlaminar shear strengths of untreated graphite-epoxy composites are 2000 to 4000 p.s.i. A strength of more than 12,000 p.s.i. has been obtained by whiskerizing Union Carbide's Thornel 25 graphite fiber. TKF says the whiskerizing process is relatively inexpensive and works equally well on single strands of graphite yarn or on multiple layers of woven fabric. Ethylene may prove to be a plant hormone that controls growth and maturation of fruit, say Dr. Edward C. Maxie and Dr. Julian C. Crane, pomologists at University of California's school of agriculture, Davis. The chemical is a normal metabolic product of many plants, they note. The pomologists find that a mixture of 5 p.p.m. ethylene in air causes rapid ripening of young growing figs. They enclosed the small, green fruits in polyethylene and passed in the gas mixture for six days. At the end of that time the fruit had grown to normal size, a month or more ahead of schedule. Dr. Maxie and Dr. Crane hope to control the rate at which plants produce ethylene, making possible the regulation of fruit maturity. International Nickel Co. has developed a high-strength copper alloy containing nickel (30%) and chromium (2.8%). The alloy, called IN 732X, has a yield strength of 50,000 p.s.i. Conventional 70/30 copper-nickel alloys yield at about 18,000 p.s.i., Inco says. The company adds that IN 732X matches or surpasses conventional copper-nickel alloys in resisting corrosion in sea water. The high strength of the new material may extend the already wide marine use of copper-nickel alloys, Inco says. DEC. 4, 1967 C&EN 55
