scheduled for North America and very little in Europe during the same period, Freeman told the conference, which was sponsored by the Fertilizer Institute and which attracted about 1000 people from more than 40 countries. In addition, he says, Japan's ammonia capacity has been cut back because of high energy costs. All three areas—North America, Europe, and Japan—have been large suppliers of nitrogen fertilizers. Increased energy costs also were discussed at the meeting. Edwin M. Wheeler, president of the Fertilizer Institute, said that substantial increases in world oil prices next year could be devastating to the current fertilizer price structure, but are not expected to result in a reduction of fertilizer use. Fertilizer production costs have been escalating 15 to 20% per year and freight charges alone have risen 19%, Wheeler says. Ocean shipping rates have gone up about 35%. However, he told the conference, U.S. farmers' anxiety over increasing prices is not expected to cause a cutback in application rates. Wheeler bases his prediction on early indicators plus farmers' spendable income. Preplanting ammonia demand for fall wheat seeding and a drop in U.S. inventories of fertilizer add to his optimism. The Fertilizer Institute had reported earlier that domestic fertilizer use rose 6% for July, the first month of the fertilizer year, whereas inventories generally fell (C&EN, Sept. 10, page 13). D
New polycarbonate may replace autoglass General Electric says it has overcome a major obstacle to the use of polycarbonate sheet for automotive glazing applications. A new siliconecoated polycarbonate, Margard, is, according to the company, nearly as abrasion-resistant as glass. Polycarbonate sheet offers outstanding impact resistance as well as good flame resistance and weatherability, GE notes. However, glazing applications have been held back by the fact that polycarbonate mars rather easily. Its abrasion resistance can be improved by applying an organic "hardcoat." That coated material is suitable for glazing applications in which polycarbonate's virtual unbreakability is more important than its susceptibility to scratching. But it hasn't been suitable for automobiles, in which the plastic would be subject to scratching by windshield wipers, wind-blown grit, and even the 8
C&EN Oct. 1, 1979
rotating brushes used in automatic car washes. However, GE says, the new silicone-coated material has been shown, in standard abrasion tests, to resist abrasion nearly as well as glass, and four to five times better than existing coated polycarbonates. Key to the success of the siliconecoating process is a proprietary primer, developed at GE's R&D center, which makes possible bonding the silicone to the substrate. Previously, a "weathering effect" had frustrated attempts to apply silicone coatings to polycarbonate. GE notes that it is "particularly excited" about the possibility of automotive uses for Margard. Although polycarbonate costs roughly three times as much as tempered glass, it's only about half as dense. Consequently, GE says, "It could fit right in with the automobile industry's efforts to reduce vehicle weight and thus increase gasoline mileage." Before Margard can be used for car
windows, it must be "certified" by the auto industry and by the U.S. Department of Transportation. A battery of tests designed to gain this certification is currently under way at GE's testing laboratories, the company says. The new material is already finding uses in other transportation equipment. GE notes that a major maker of off-highway equipment has replaced wire-reinforced safety glass with Margard. Amtrak has specified the silicone-coated material for the side windows of 1800 new passenger cars. And the Milwaukee transit system, in addition to specifying Margard for new buses, eventually will use it to replace first-generation plastic glazing in older buses. GE says that its plastics division plans to begin commercial production of Margard sheet before the end of the year. It will be available in green, gray, bronze, or clear, and in standard polycarbonate sheet thicknesses ranging from Vs to V2 inch. D
Approvals for pyrethrum substitutes stepped up Shortages of the natural insecticide I pletion of studies of their long-term pyrethrum are causing the Environ- health and environmental effects. mental Protection Agency to speed Among the pyrethrins allowed in up approvals of its synthetic substi- these products are some of the most widely used ones: permethrin, Dtutes. EPA has "conditionally registered" phenothrin, tetramethrin, resmethseveral of the substitutes, called py- rin, and allethrin. Manufacturers of another 150 pyrethrins, for use in insecticides. The agency also is willing to let farmers rethrin-containing insecticides have make emergency use of the synthetic been informed that their products compounds to control flies in poultry also can be conditionally registered, provided that they submit certain houses and dairy barns. The natural compound, which is labeling and other required inforextracted from certain types of chry- mation to EPA. Another 150 requests santhemum flowers, has been in short to register pyrethrin-containing supply for the past two years. About products still are pending at EPA. EPA also has given emergency au65% of the world production comes from Kenya, where bad weather and thority to poultry producers in four the greater profitability of other states to use permethrin to control crops, such as coffee, have led to de- flies in their chicken houses. And it clining production. Most of the rest has advised states that they can apply comes from Ecuador and Japan, al- for emergency use of allethrin to though recent experiments show that combat flies in dairy barns. Such it is possible to grow the flowers in emergency authority applies only to New Jersey and other parts of the situations involving severe fly problems that threaten public health, and U.S. (C&EN, July 23, page 8). Pyrethrum is prized as an insecti- lasts only one year. If the projections coming from cide because it is very selective, rapidly killing insects but with very little Kenya's Pyrethrum Marketing Board toxic effect on warm-blooded ani- are anything to go by, there will be mals. It also is rapidly degraded and more natural pyrethrum available a does not leave toxic residues. Thus, its year from now but probably still not principal uses are in stock sprays, pet enough to meet demand. George sprays, household sprays, and to Kin'gori, manager of the marketing protect stored food in warehouses and board, said last spring that the 1979-80 pyrethrum crop in Kenya is shipping containers. So far, EPA has conditionally reg- expected to be about 12,000 tons of istered several synthetic pyrethrins dried flowers, up substantially from for use in about 100 insecticides. Such last year's 8400 tons. By 1981, he registration means that the ingredi- promises adequate supplies of the D ents may be used pending the corn- I natural product.
