High performance PET fibers via liquid isothermal bath high-speed spinning: Fiber properties and structure resulting from threadline modification and post treatment

摘要

Poly(ethylene terephthalate) fibers with improved mechanical properties and dimensional stability were spun in the range of 2000-5000 m/min via controlled threadline dynamics by a liquid isothermal bath (LIB) spinning process, followed by postdrawing and annealing. Fiber properties of the as-spun fibers and post-treated fibers of each process were compared. Two commercial tire cords were also included. Unlike unperturbed spinning, the LIB as-spun fibers show unique structural properties ofhigh amorphous orientation, low crystallinity, high strength, and high initial modulus. Moreover, noncrystalline chains are further extended during post treatment. The post-treated LIB fibers exhibit mechanical properties with tenacity higher than ca. 9g/d, initial modulus higher than 120 g/d, and ultimate elongation less than ca. 10%. They also demonstrate superior stability with thermal shriakage less than 6% and LASE-5 higher than 5 g/d. The overall properties are not obtainable by either thetraditional spin-draw process or any modified process which produces low shrinkage tire cord. Evidence is presented that strongly indicates the existence of a "third phase", referred to as the taut-tie nonctystalline phase (TTNC), is addition to thetraditional two-phase model, i.e. crystalline and random amorphous phases.