Different polyurethanes were synthesized by varying the diol as well as the diisocyanate components and chain extenders. Polyurethanes with OH-groups were obtained by photo-and thermoinitiation of the radical polymerization of hydroxy alkyl acrylates in the presence of the polyurethanes. The polymers were evaluated with respect to their biocompatibility by measuring the cell spreading, the rates of DNA-and protein synthesis and the swelling behaviour. The differences in the surfaces and the bulks between the selected basic polyurethane and the functionalized modification were determined and characterized by XPS, FTIR-ATR and '3C-FT-NMR-spectroscopy.The mechanical data of Tecof lex EG 60D @ and Pellethane 2363-80AE @ were compared with the data of the synthesized polyurethanes.
Langfristige Korrosionsprufungen (bis 112 517 h) mit Stahlen des Typs 03Cr18Ni13Mo2,5 mit unterschiedlicher chemischer Zusammensetzung und metallurgischer Reinheit und (bis 64 699 h) mit Stahlen des Typs 02Cr25Ni22Mo2N unter den Betriebsbedingungen bei der Harnstoffsynthese werden beschrieben. Der erstgenannte Stahltyp mit Chromgehalten uber 18% ist geeignet fur den Hochdruckteil der Harnstoffsyntheseanlage und erfiillt auch die sonstigen Anforderungen an Stahle von Harnstoffqualitat.Der Stahltyp 02Cr25Ni22Mo2N ist noch korrosionsbestandiger und daher ebenfalls bei der Harnstoffsynthese gut venvendbar, allerdings wegen des hohen Nickelgehalts nicht so wirtschaftlich.Die Gewichtsabnahme-Zeit-Kurven wurden his auf 1,5 .lo5 h extrapoliert .Long-term corrosion tests with the steel types 03Cr18Ni3Mo2.5 having different chemical compositions and chemical purity, and 02Cr25Ni22Mo2N have been carried out for up to 112517 and 64 699 h, respectively, in the urea manufacture environment. According to the results the first steel is a suitable material of construction for the high pressure parts of urea plant, provided its chromium content is higher than 18%. This quality meets requirements of urea grade steels.The steel 02Cr25Ni22Mo2N is even more corrosion resistant, but its use may be critical because of the high nickel content.A mathematical model has been developed for the weight loss-time-dependence and the results have been extrapolated to up to 1.5 . lo5 h.
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