TRANSPORT OF IODINE IN POLY(ETHYLENETEREPHTHALATE)

Iodine sorption characteristics of poly(ethyleneterephthalate) have be en studied through free volume changes by the positron annihilation li fetime (PAL) technique. The results show swelling of the polymer, char ge transfer complex (CTC) formation in the initial stages and precipit ation of iodine in the final stages df sorption. Additionally, the res ults suggest a conformational transformation in the amorphous region o f the polymer in the final stages of sorption which is in agreement wi th the earlier predictions. It is also revealed that iodine acts more as an inhibitor than a quencher of the o-Ps. The average free volume s ize suggests that the predominant species which fills the free volume holes during iodine sorption is I-3(-). The sorption in PET obeys Case II diffusion. Furthermore, the study shows that Fujita's free volume theory, which relates the fractional free volume and diffusion coeffic ient, deviates. (C) 1997 Elsevier Science Ltd.