Studies on solution-grown crystals of polyethylene terephthalate and some copolyesters. II. Physical properties of the solution-grown crystals add the hydrolyzed crystals

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Abstract
The viscoeiastic properties and the wide-line NMR spectra of solution-grown crystals and hydrolyzed crystals of polyethylene terephthalate and some copolyesters were measured. A new NMR narrowing and new viscoelastic absorption were observed at temperatures higher than that of the primary dispersion of the solution-grown crystals for all polymers cited above. It was clarified from the thermal expansion curve of the crystal lattice, as determined by X-ray diffraction, and from the crystallinity dependence of the absorption intensities that the new dispersion is caused by molecular motion in the crystalline region. The primary dispersion of the hydrolyzed crystals could scarcely be observed and only the narrowing corresponding to the crystalline dispersion was observed. This suggests that the loop region of the lamellar crystals was removed and the “pure” crystal was obtained.

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