Mechanism of cold drawing in melt‐spun poly(ethylene terephthalate) fibers

An investigation has been made into the mechanism of cold drawing in melt‐spun poly(ethylene terephthalate) (PET) fibers. An analysis of the cold‐drawing behavior using wide‐angle x‐ray diffraction, orientation measurements, calorimetric and mechanical techniques was performed. The evidence suggests that the cold‐drawing process involes stress‐enhanced crystallization which occurs in conjuction with incresing orientation of the crystalline and amorphous regions. A degradation in the fiber properties after cold drawing was observed for fibers spun below 1,000 m/min while fibers spun above 1,000 m/min exhibited an improvement in fiber properties with cold drawing. This behavior was explained by the existence of two distinct irreversible deformation micromechanisms for fibers spun below and above 1,000 m/min.