The infrared spectrum of polutrthylene terephthalate. II. Polyethylene‐<i>d</i>₄ terephthalate

Abstract

Abstract Polyethylene‐ d 4 terephthalate was prepared from dimethyl terephthalate and 1,2ethane‐ d 4 ‐diol. This polymer also showed spectral changes by drawing and heattreatment as in the case of polyethylene terephthalate. Comparison of the deuterated polymer spectrum with that of ordinary polymer, reveals the bands associated with ethylene glycol residue quite clearly. Almost all the bands which change their intensities by crystallization, belong to ethylene glycol residue vibration. From the shifts on deuteration, the bands of polyethylene terephthalate at 1101, 1042, and 973 cm. −1 are assigned to C‐O vibrations. Vibrational frequencies associated to terephthalic acid residue remain unchanged on deuteration of the ethylene glycol residue. Assignments for p ‐substituted benzene residue are given, based on the assignments of benzene, p ‐benzene‐ d 2 , p ‐xylene, etc. The bands at 873 and 727 cm. −1 are both assigned to the coupled vibrations of aromatic out‐of‐plane CH bending mode and out‐of‐plane OCO bending mode. These two modes seem to have a considerable interaction with each other in aromatic esters.