Improvement of Dyeability of Poly (ethyleneterephthalate) Fibers by High Temperature Short Period Heat Treatment

Abstract

An attempt was made to improve the dyeability of Poly (ethyleneterephthalate) (PET) fibers, keeping physical properties suitable for pratical use, by controlling the amorphous supermolecular structure. For the purpose, as-spun fibers spun at various winding speed were heat-treated with a wide variation of heating temperature Ta, heating time ta and tension f. Subsequently to the heat treatment, the fibers were, if neccesary, subjected to drawing at 100°C. Measurements of dye exhaustion of disperse dye Resolin Blue FBL, tensile strength and elongation, dynamic viscoelasticity, X-ray diffraction and differential scanning calorimetry were carried out for evaluation of dyeability, physical properties and supermolecular structure of the fibers. It become evident that even the conventional PET fibers, which were spun at winding speed of 1.5 km/min and followed by hot drawing (×3.9), makes them dyeable by disperse dye at 100°C keeping 3g/din Tensile strength and 20 to 40% of tensile elongation by heat treatment under the condition of Ta=255-260%, ta=1sec and f=0.1g/d. All the PET fibers, which were spun at winding speed of 3-9 km/min, become dyeable at 100°C by applying the high temperature, short period heat treatment. All the PET fibers investigated here showed that the dyeability is predominently governed by two parameters ; maximum value of mechanical loss tangent tanσA in a-dispersion region and its peak temprature, and is not significantry correlated with the crystallinity and the crystalline orientation.