EVOLUTION OF HOT STRAIN-INDUCED CRYSTALLINE TEXTURE OF POLY(ETHYLENE-TEREPHTHALATE) FILMS

Differential scanning calorimetry, birefringence and X-ray poles figur e analysis were used to characterize the evolution of the strain induc ed crystalline texture of poly(ethylene terephthalate) films. The film s are initially wholly amorphous and drawn above the glass transition temperature. For a critical draw ratio, a crystalline phase appears wi th a weak crystalline fiber texture. For the highest draw ratio we obs erve that the texture is better defined, and the drawing tends to alig n the crystallites with the draw direction and to increase slightly th e degree of crystallinity. For the highly drawn sample an extra textur e is also observed.