Graft copolymerization studies Part II. Models related to polyethylene terephthalate

The chemistry of free radical graft copolymerization, initiated with t-buto xy radicals, has been investigated using ethylene glycol dibenzoate and die thylene glycol dibenzoate as models for polyethylene terephthalate (PET). A lthough diethylene glycol dibenzoate is more reactive than ethylene glycol dibenzoate the site of grafting from the polymer is determined by the conce ntration of ethylene glycol and diethylene glycol residues and the relative reactivity at these positions. Hence grafting occurs most frequently at th e ethylene glycol positions. This study also suggests that PET is less reac tive than the polyolefins LLDPE and polypropylene and that PET chain scissi on is possible using high t-butoxy radical concentrations in the presence o f adventitious oxygen at relatively low temperatures. (C) 2000 Elsevier Sci ence Ltd. All rights reserved.