Zone drawing and zone annealing of poly(ethylene terephthalate) microfiber prepared by CO 2 laser thinning

A zone‐drawing and zone‐annealing method was applied to a poly(ethylene terephthalate) microfiber, obtained by using CO 2 laser thinning, to develop its mechanical properties. The microfiber used for the zone drawing and zone annealing was prepared by winding at 1386 m/min the microfiber obtained by irradiating the laser at 18.1 W/cm 2 and had a diameter of 2.8 μm and a birefringence of 0.097. Zone drawing was carried out at a drawing temperature of 105°C under an applied tension of 53 MPa, and zone annealing at an annealing temperature of 155°C under 195 MPa applied tension. Zone drawing and zone annealing were carried out at a treatment speed of 0.21 m/min. The diameter of the microfiber decreased, and its birefringence increased, with zone drawing and zone annealing. The zone‐annealed microfiber finally obtained had a diameter of 2 μm, a birefringence of 0.234, a tensile modulus of 17.9 GPa, and a tensile strength of 1.1 GPa. The wide‐angle X‐ray diffraction photograph of the zone‐annealed microfiber showed the existence of highly oriented crystallites. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 92: 2989–2994, 2004