Bimodal character of polyester–solvent interactions. II. Evaluation of the chemical structures of the aromatic and aliphatic ester residues of poly(ethylene terephthalate)

摘要

AbstractThe chemical structures of the aromatic (A) and the aliphatic ester (B) residues of poly(ethylene terephthalate), PET, are evaluated from a comparison of their Hansen solubility parameters, as determined experimentally, and with those calculated for the various residues of PET. From such a comparison it is proposed that the structures of residues A and B are best represented by “hybrid” structures which may be taken as linear combinations of two or more structures rather than by single chemical structures. That is, the 1,4‐carbonyl group which separates the benzene ring of the aromatic residue and the ethylene group of the aliphatic ester residue effectively acts as a common plane between the two residues and is “shared” by the benzene ring and the ethylene glycol group. It is proposed that the extent to which the 1,4‐carbonyl group is “shared” by residues A and B is 0.33 and 0.67, respectively, which is consistent with the most probable molecular conformation of the 1,4‐benzenoid residue of PET as calculated from the data of Tonelli23and Daunbeny et al.21and which gives support to the view that the bond connecting the benzene ring and the carbonyl group is not rigid, but free to rotate as proposed earlier by Flory