A study of the vacuum gamma-radiolysis of two aromatic polyimide fluoropolymers containing phenylphosphine oxide

The vacuum gamma -radiolysis of two fluorinated polyimides containing pheny lphosphine oxide units, TOR-RC and TOR-RC ODPA, have been studied at 77 K a nd 300 K. The phenyl phosphine oxide units provide protection of the polyme rs towards oxidation by oxygen atoms and the bulky fluoromethyl groups redu ce the colouration of the polymers by limiting donor-acceptor complex forma tion through the aromatic units. At 77 K the radicals formed were identifie d to be a mixture of neutral radicals (60%) and anion radicals. At 300 K on ly neutral radicals were found. The G-values for radical formation were fou nd to be 0.50 and 0.42 at 77 K and 0.051 and 0.052 at 300 K for TOR-RC and TOR-RC ODPA, respectively. Little change was observed in the visible spectr a of the polyimides following vacuum radiolysis at 300 K up to a dose of 3. 3 MGy, and the polymers were shown to undergo net cross linking with a gel dose of 0.45 MGy.