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.