Fabrication of high-strength polyoxymethylene fibers by gel spinning

High-strength polyoxymethylene (POM) fibers were obtained by gel spinning with an oligomer–polymer blend instead of a conventional solution in an organic solvent. An optimal ratio of 80/20 (weight/weight) caprolactam/POM blend formed a gel upon cooling to ambient temperature and exhibited a melting temperature of 145 °C. The resulting blend was used in gel spinning of POM fibers with a 3-stage drawing process. Some outstanding features of a gel-spun POM fiber include a draw ratio of 40, a tensile strength at break of 2.01 ± 0.11 GPa and a Young’s modulus of 40.60 ± 0.69 GPa. The draw ratio and tensile strength of POM are significantly improved compared to those previously reported. The relationship between processing, structure and property was also investigated. Wide-angle X-ray diffraction and Raman spectroscopy demonstrate high crystallinity and good molecular orientation along the fiber drawing direction.