Polyimides results

The dielectric constant of dry (0%RH atmosphere) 6FDA/TFDB is as low as 2.8 because of its four trifluoromethyl groups (fluorine content 31.3%). The low dielectric constant of fluorinated polyimides results from the low electronic polarizability of fluorine-containing groups and the reduced chain-chain elec-... 

Reactions Between Epoxy-Polyimide Resulting in IPN Formation... 

Despite this progress, SEC with HFIP remains an expensive procedure due to extra investment in fluorinated solvent and special columns. Finally, it should be noted that HFIP with a of 9.3 is sufficiently acidic to react with the nitrogen in aromatic polyimides, resulting in ring-opening solvolysis. 

Polyimide. A typical polyimide results from the condensation of pyromellitic dianhydride and bis-4(aminophenyl)ether. The final insoluble polydiimide is obtained by dehydration of a soluble polyamic acid, namely,... 

There are two basic types of polyimides condensation and addition resins. The condensation polyimides are based on a reaction of an aromatic diamine with an aromatic dianhydride. A tractable (fusible) polyamic acid intermediate produced by their reaction is converted by heat to an insoluble and infusible polyimide, with water being given off during the cure. Generally, the condensation polyimides result in products having high void contents that detract from optimal mechanical properties and result in some loss of long-term heat resistance. 

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