STUDY ON THE STRUCTURE OF UNIAXIALLY COLD DRAWN POLY(ETHYLENE-TEREPHTHALATE) BY HIGH-RESOLUTION SOLID-STATE C-13 NMR-SPECTROSCOPY

Regularity produced by drawing was discussed on the basis of the results of C-13 CP/MAS NMR spectra and relaxation time measurements of poly(ethylene terephthale) in the solid state. Change in the C-13 CP/MAS specrta and the chemical shifts of the carbonyl and aromatic carbons were not observed by drawing. However, the peak of the methylene carbon was broad asymmetric, and shifted to a higher field with an increase in the draw ratio. In addition, the peak of the carbonyl carbon of the crystallized sample shifted to a higherfield, and a shoulder appeared at the lower fieldsite. On heat-treatment, the chemical shift of thearomatic carbon did not change, but the line widthbecame narrow. The peak of the methylene carbon shifted to a higher field, and the line width of the spectrum became narrow. The relaxation times (CP-T1, PST-T1, and CP-T1rho) of methylene, aromaticand carbonyl carbons were independent of drawing. They were, however, affectted by heat-treatment. It is concluded that the regularity produced by drawing is essentailly different from that produced by heat-treatment.