Abstract
In preliminary experiments to optimize the condition of a laser heating, zone drawing for poly(ethylene terephthalate) (PET) fiber, a microfiber was prepared by a continuousβwave carbon dioxide (CW CO~2~) laser heating. CW CO~2~ laser heating was carried out at an extremely low applied tension (Ο~a~) at a higher laser power density (PD) as compared to the optimum condition for the laser heating, zone drawing of PET fiber reported previously. The microfibers were obtained by CO~2~ laser heating carried out at a PD of 15.8 W cm^β2^ and under a Ο~a~ of 0.66 MPa or lower. The diameter of the fiber decreased with a decreasing Ο~a~ and increasing PD. The smaller the diameter, the higher was its birefringence. The smallest diameter fiber obtained at Ο~a~ = 0.17 MPa at PD = 21 W cm^β2^ had a diameter of 4.5 ΞΌm and a birefringence of 0.112, and its draw ratio estimated from the diameter reached 3086 fold. Such a high draw ratio was not previously attained by any drawing method. In a wideβangle Xβray diffraction photograph of the smallest diameter fiber, indistinct reflections due to oriented crystallites were observed. An SEM micrograph of the smallest diameter fiber showed a smooth surface without any crack and was uniform in diameter. Β© 2003 Wiley Periodicals, Inc. J Appl Polym Sci 88: 3297β3283, 2003