Synthesis, characterization and ESR study of the gamma-radiolysis of aromatic polyesters containing isomeric naphthalene links

Abstract

Six polyesters were synthesized from 4,4'-(hexafluoroisopropylidene) -bis(benzoyl chloride) and 1,4-, 1,5-, 1,6-, 2,3-, 2,6- and 2,7-naphthalene diol (ND) isomers. The structures of the polyesters were characterized by IR spectroscopy and the results were in good agreement with the expected structures. Inherent viscosities of tetrachloroethane, (TCE) solutions at 303K ranged from 0.11 to 0.46 dlg(-1) The glass transition temperatures were found to be in the range 425-494 K by DSC thermal analysis. Thermogravimetric analyses showed two-stage weight losses and revealed the excellent thermal stability of the polymers. All the polyesters were irradiated in an AECL Gammacell 220 unit at a dose rare of approximately 6.7 kGy h(-1) to doses in the range 0-15 kGy at 77 K and 300 K. The G values for radical formation in the polyesters were found to be in the range 0.41-0.81 at 77 K and 0.56-1.49 at 300 K. At 77 K up to 15% of the radicals formed on radiolysis were found to be anionic. Annealing experiments were carried out to identify the neutral radicals, which were assigned Co phenyl, benzoyl and phenoxyl radicals. (C) 1999 Society of Chemical Industry.