Radiation chemistry of arylpolyester blends with a polyalkanoate

The gamma-radiolysis of a series of blends of bisphenol-A polycarbonate and poly(bisphenol-A-co phthalate) with poly(3-hydroxybutyrate-co-3-valerate) has been investigated at 77 K. The ESR spectra of the radicals formed on ra diolysis have been delineated and compared with the spectra which would be expected for a linear additive model. This comparison showed that these was a greater contribution to the spectrum from the aromatic polyesters than f rom the aliphatic polyester. However, the radiation chemical yields for rad ical formation were found to adhere closely to the predictions of the linea r additive model. This latter observation suggests that the blends are not miscible at the level required for effective radiation protection of the al iphatic polyester which has a much higher sensitivity to radiation damage. Thermal analyses of the blends showed two glass transition temperatures at those of the homopolymer components, typical of the behaviour of a phase-se parated system, but there was also evidence of a modified crystalline struc ture in the aliphatic polyester through a depression of the melting tempera ture in the blends. (C) 1999 Society of Chemical Industry.