Wide-Line Nuclear Magnetic Resonance Studies of Poly (Ethylene Terephthalate)

Wide-line nuclear magnetic resonance (NMR) studies have been made as a function of temperature and the angle between the stretch direction and the magnetic field on one-way stretched poly (ethylene terephthalate) film. The data obtained were consistent with a structural model, the important features of which are the directions of the lines between interacting methylene and aromatic protons relative to the stretch direction. Evidence for planar orientation in one-way stretched poly (ethylene terephthalate) film was obtained from wide-line NMR data which were taken as a function of the angle between the normal to the film surface and the magnetic field. A difference of approximately 25°C has been observed in the temperature at which the sharp component appears in annealed, unoriented poly (ethylene terephthalate) film and powder phase material from the solid-phase buildup reaction. This difference is explained as being due to a difference in the degree of crystalline perfection.