A comparative study of the radiation resistance of four optically transparent polyimides

A comparative study of the high energy radiation resistance to formation of radicals in two pairs of polymers is reported. In one pair of polymers the phenyl groups containing the imide rings are separated by an ether linkage and in the other pair they are separated by an hexafluoroisopropylidine gr oup. Two of the polymers contained aromatic amine units linked through an e ther linkage and the other two polymers contained a trifluoromethyl bipheny l diamine. The polymers were shown to retain a high level of transparency i n the visible region following radiolysis to doses as high as 8 Gy. ESR stu dies of the resistance to radical formation on radiolysis. at 77 K revealed that the polymers containing ether linkages were more stable than their fl uorinated analogues, but all were less stable than Kapton (R). (C) 2001 Els evier Science Ltd. All rights reserved.