Mechanical Properties and Superstructure of Poly(ethylene terephthalate)Fibers Zone-Drawn and Zone-Annealed by CO_2 Laser Heating

摘要

A laser-heating zone-drawing and zonc-annealing method using a contin-uous-wave carbon dioxide laser was applied to poly(ethylene terephthalate)(PET) fiber to imjprove its mechanical properties.The as-spun fiber was zone-drawn under a applied tension (#sigma#_a) of 4.44 MPa at a laser power density (PD) of 6.08 W cm~(-2),and then the laser-heated zone-drawn fiber was zone-annealed.The laser-heating zone-anneal-ing was carried out in three steps:the first annealing was carried out under #sigma#_a=283 MPa at 4.83 W cm~(-2),and the third annealing was carried out under #sigma#_a=432 MPa at 3.45 W cm~(-2).The surface temperature distribution of the fiber irradiated with the CO_2 laser was measured by using an infrared thermographic camera equipped with a magnifying lens.The relation between the laser power and the surface temperature of the fiber became clear in the laser-heating zone-drawing and the laser-heating zone-annealing.The fiber obtained finally had a birefringence of 0.239,a degree of crystallinity of 55%,a tensile modulus of 19.8 GPa, and a storage modulus of 25.7 GPa at 25 deg C.In FTIR measure-ments,a trans conformation increased with the processing,but a gauche one decreased.The laser-heating zone-drawing and zone-annealing method was found to be effective in producing the PET fiber with high modulus and high strength.