News of the Week forts, commercial resources, and licensing rights to its advanced composites fabrication technologies. United Technologies will contribute its existing Sikorsky Aircraft production facility in Tallassee, Ala., along with research, engineering, and design groups located in Connecticut. The new company will be based in Connecticut and will employ about 500 people. Ann Thayer
New technology yields polycarbonates
Bisphenol A
Bis(chloroformate)
Catalyst
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FROM MIAMI BEACH
New polymerizations broaden carbonate uses New developments in polymerization of carbonates at General Electric promise to expand markets for these polymers in a range of products including windows and sporting equipment. These processes open doors to new composites and crosslinked resins and to better ways of fabricating polycarbonates. Some of the details of the technologies were unveiled last week at the American Chemical Society meeting in Miami Beach. The t e c h n i q u e , says John W. Verbicky, manager of GE Research & Development Center's chemical synthesis laboratory, is based on the first practical synthesis of very large cyclics. It is also applicable to polyarylates, aramids, and ether/ thioether-imide and -sulfone resins. U.S. consumption of polycarbonates will be almost 500 million lb in 1989. Domestic producers are Dow (100 million lb per year capacity), GE (420 million lb), and Mobay (160 million lb). Notable among the c u r r e n t diverse applications of polycarbonates are windows (25%), transportation (15%), electrical and electronic devices (12%), and industrial (11%) and sporting equipment (10%). One polycarbonate technology, Verbicky says, is based on reaction of bisphenol A and its bis(chloroformate) ester to form cyclic oligomers ranging from 24 rings to 240. This material is a powder that, when heated, melts and flows easily into the tight spaces in a complex fiberreinforcing network. 8
September 18, 1989 C&EN
Polycarbonate Cyclic oligomers n = 1-20
g Anionic catalysts trigger opening of rings, whose "living" anionicc o ends attack other rings, leading to ichain growth. Catalyst concentra:s tions control molecular weights that range from 50,000 to 700,000. ). Molecular weights of conventionald polycarbonates, made by reaction of>f b i s p h e n o l A a n d p h o s g e n e , aree 40,000 to 60,000. Crosslinked polycarbonates resultIt
from inclusion of such compounds as the internal cyclic bis(carbonate) of l,5-tetrakis(3,5-dimethyl-2-hydroxyphenyl)pentane or a copolymer of styrene and glycidyl methacrylate in the oligomer mixture, Ring-opening polymerization of cyclic oligomers made by reaction of bisphenol A and isophthaloyl chloride yields polyarylate resins. Stephen Stinson
FROM MIAMI BEACH
ing. "It has become commonplace to suggest that vegetation might sequester major amounts of carbon and that the additional large-scale planting of trees might provide an additional sink for carbon," Botkin told attendees at last week's meeting of the American Chemical Society, Since there was no agreement on the boundaries of the boreal forests, Botkin defined them with environmental features. He used July mean isotherms to set the north and south boundaries and subdivided the area into 12 regions whose boundaries were defined by climatic, geologic, and soil patterns. Equal-sized units were sampled in each region. Botkin says his study is the first attempt to gather statistically reliable estimates of vegetation biomass for a large area of Earth. In other studies, areas with mature trees were sampled and the measurements extrapolated to large regions. Botkin notes there is a general lack of information on the interactions between global climate and vegetation, Bette Hileman
Forest survey finds 75% less biomass rThe northern forests of North Ameris ica may contain only one fourth as imuch biomass as previously calcud lated report Daniel B. Botkin and y Lloyd G. Simpson of the University of California, Santa Barbara. rEach square meter of the everrgreen forest, according to their survey sample, contains an average of>f >about 4 kg of above-ground biomass. The entire forest has a total of>f iabout 22 billion metric tons. Previ)ous estimates of the average bio?r mass contained in one square meter range from 12 to 18 kg. 5Large-scale measurements are esil sential for understanding global d warming, because they are needed >r for determining the potential for forests to absorb the carbon dioxidee il produced by the burning of fossil ll fuels and for determining how much rcarbon is released by forest clear-
