Effect of diethylene glycol content and annealing temperature on the structure and properties of poly(ethylene terephthalate)

Abstract

Abstract The effect of 2,2′‐oxydiethanol (diethylene glycol, DEG) content (ranging from 2 to 15 mol %) and of the annealing temperature (in the range from 100 to 260°C) on the density, calorimetric, dynamic‐ and static‐mechanical and small angle X‐ray scattering (SAXS) behavior of undrawn and drawn samples (granules, films, and bristles) of poly(ethylene terephthalate) (PET) has been studied. The known dependences on the annealing temperature are confirmed. Some discrepancies with earlier investigations of the dependences on the DEG content are established: constant values for the SAXS intensity and long spacing, for the lamellar thickness and for the volume fraction crystallinity a c . These discrepancies are explained by the variation of the glass transition temperature ( T g ) and melting temperature ( T m ) of the materials with different DEG contents. The previous hypothesis of the segregation of the comonomer (DEG) units into the amorphous regions is confirmed.