Preparation of high‐modulus and high‐strength poly(ethylene terephthalate) film by zone‐annealing method

Abstract

Abstract The zone‐annealing method was attempted to prepare high‐modulus and high‐strength poly(ethylene terephthalate) (PET) film. The film having Young′s modulus of 14.5 × 10 10 dyn/cm 2 and a tensile strength of 86.9 kg/mm 2 in the drawing direction was obtained. These values correspond to four times those of a biaxial‐stretched PET film available commercially. The dyanmic viscoelastic properties also were measured. The dynamic storage modulus was 15.4 × 10 10 dyn/cm 2 at room temperature, and a high value of 3.6 × 10 10 dyn/cm 2 even at 200°C. The latter value is slightly higher than the room temperature modulus of the commercially available film. From the intensity and temperature position of α‐dispersion E″ peak, it was suggested that the amorphous chains in the zone‐annealed film was densely packed in a highly oriented state. Furthermore, the crystallinity, orientation, especially double orientation, and molecular chain conformation of the films in the zone‐annealing process are discussed in the present paper.