5,745 research outputs found
Literature review of mechanisms of interaction of ethylene oxide and organic and inorganic materials
Mechanism of interaction of ethylene oxide and polymeric and inorganic compound
An improved processible acetylene-terminated polyimide for composites
The newest member of a family of thermosetting acetylene-substituted polyimide oligomers is HR600P. This oligomer is the isoimide version of the oligomer known as HR600P and Thermid 600. Although both types of material yield the same heat resistant end products after cure, HR600P has much superior processing characteristics. This attributed to its lower melting temperature (160 + or - 10 C, 320 + or - 20 F) in contrast to 202 C (396 F) for Thermid MC-600, its longer gel time at its processing temperature (16 to 30 minutes bvs 3 minutes), and its excellent solubility in low boiling solvents such as tetrahydrofuran, glymes, or 4:1 methyl ethyl ketone/toluene mixtures. These advantages provide more acceptable coating and impregnation procedures, allow for more complete removal at lower temperatures, provide a longer pot life or working time, and allow composite structure fabrication in conventional autoclaves used for epoxy composite curing. The excellent processing characteristics of HR600P allow its use in large area laminated structures, structural composites, and molding compositions
New hyperthermal thermosetting heterocyclic polymers
Polyimidazopyrrolone polymers, formed by the condensation of aromatic dianhydrides with aromatic tetraamines in various solvents, form moldings that resist degradation in air and retain great strength at 400 to 700 degrees F. The resins have good insulating properties, are easy to mold, and make good protective coatings
Study of the effects of ethylene oxide-freon 12 upon properties of polymers and metallic surfaces Final report, 10 Oct. 1964 - 31 Mar. 1966
Physical, mechanical, and electrical tests to determine the effects on polymeric products after exposure to ethylene oxide-Freon 1
Measuring Violence Against Children in Humanitarian Settings: A Scoping Exercise of Methods and Tools.
Letter From Nancy L. Wood to Eleanor Snell, May, 1970
This letter from Nancy L. Landis, Ursinus College Class of 1943, congratulates Eleanor Snell on the occasion of her retirement from Ursinus College and remarks on Eleanor\u27s devotion to her students.https://digitalcommons.ursinus.edu/snell_docs/1045/thumbnail.jp
Development of improved heat sterilizable potting compounds third quarterly report, 1 jan. - 31 mar. 1964
Development of heat sterilizable potting compoun
Material processing with hydrogen and carbon monoxide on Mars
Several novel proposals are examined for propellant production from carbon dioxide and monoxide and hydrogen. Potential uses were also examined of CO as a fuel or as a reducing agent in metal oxide processing as obtained or further reduced to carbon. Hydrogen can be reacted with CO to produce a wide variety of hydrocarbons, alcohols, and other organic compounds. Methanol, produced by Fischer-Tropsch chemistry may be useful as a fuel; it is easy to store and handle because it is a liquid at Mars temperatures. The reduction of CO2 to hydrocarbons such as methane or acetylene can be accomplished with hydrogen. Carbon monoxide and hydrogen require cryogenic temperatures for storage as liquids. Noncryogenic storage of hydrogen may be accomplished using hydrocarbons, inorganic hydrides, or metal hydrides. Noncryogenic storage of CO may be accomplished in the form of iron carbonyl (FE(CO)5) or other metal carbonyls. Low hydrogen content fuels such as acetylene (C2H2) may be effective propellants with low requirements for earth derived resources. The impact on manned Mars missions of alternative propellant production and utilization is discussed
Design and testing of vibration absorbing oceanographic cable terminations
Thesis (M.S.)--Massachusetts Institute of Technology, Dept. of Ocean Engineering, 1995.by Ethan L. Butler.M.S
Cascading Activation Revisited: How Audiences Contribute to News Agendas Using Social Media
Social media have become conduits through which audiences can challenge elites in media and politics. Recent updates to cascading activation, originally developed to explain how frames flowing from powerful figures gain public dominance, give greater theoretical scope for audiences to exert influence. Yet empirical understanding of how and in what circumstances this happens with respect to agenda-setting - another core media effect - is not well-developed, especially given the affordances of digital technologies. We address this gap by connecting theorization on cascades to developments in intermedia agenda-setting. Specifically, we analyze the dynamics surrounding the perceived reluctance by ARD-aktuell, the newsroom of Germany's public broadcasting consortium, to use its prime-time broadcast "Tagesschau" to report the arrest of a refugee accused of murdering a German woman in December 2016. By presenting finely grained timelines linking content analysis of 5,409 Facebook comments with Tagesschau editorial responses and parallel media coverage of this event, we contribute further conditions under which audience-informed cascades may occur: notably, when publicly funded news organizations are involved, and the issue at stake invokes both domestic and international aspects which sustain disagreement
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