Structure evolution and performance of poly (vinyl alcohol) fibers with controllable cross-section fabricated using a combination of melt-spinning and stretching

Profiled fibers are gained potential applications in the fields of both functional textiles and cements reinforcements. While the commercial Poly (vinyl alcohol) (PVA) fibers are generally produced by solution spinning, which is difficult to prepare profiled PVA fiber with controllable cross-section because of bidirectional mass transfer in coagulation bath. In this work, based on intermolecular complexation and plasticization, water was adopted to improve the thermal-processing of PVA, the special-shaped PVA fibers such as triangular, trilobal, cruciform and wavy cross-sections were prepared by melt-spinning. The crystallinity of profiled as-spun PVA fibers was lower than 32%, and their elongation at break was higher than 400%, resulting in good stretch-ability for hot-drawing. During the hot-drawing of profiled PVA fibers, the circular trend of the characteristic sections can be controlled, and the reduction in profile degree was lower than 9.4%. Hot-drawing improved the crystalline structure of PVA, and increased the crystallinity, orientation, tensile strength, and melting point of profiled fibers. When the draw ratio was 9, the tensile strength of triangular, cruciform, trilobal and wavy fibers were 585 MPa, 559 MPa, 481 MPa and 585 MPa, respectively, which proposed a new processing technology of special-shaped PVA fiber and enriched the kinds of special-shaped fibers.