POLYIMID MED HOG TERMISK STABILITET, OXIDATIONSSTABILITET OCH HYDROLYTISK STABILITET SAMT HOG DRAGHALLFASTHET OCH FORLENGNINGSFAKTOR INOM TEMPERATUROMRADET -45?59C TILL 260?59C

摘要

1472724 Polyimide NATIONAL AERONAUTICS & SPACE ADMINISTRATION 11 July 1975 [11 July 1974] 29187/75 Heading C3R A polyimide comprises repeating units wherein Rf is -(CF 2 ) n - or n is 2 to 10; m is 1 to 10; x and y are each 0 to 3; and x+y=0 to 5. They may be prepared conventionally by reacting the appropriate dianhydride and diamine (the preparations of which are described), optionally together with a trifunctional branching agent, e.g. 2 to 20 equivalent per cent of mellitic trianhydride, but the initial reaction stage to form the polyamide-acid intermediate proceeds more slowly than with conventional polyimides. The polyimide is stated to have suitable properties for use as fuel tank sealants in aerospace structures.