An effective strategy for the continuous fabrication of melt‐spun sea‐island bicomponent fibers with structural regulation via stretching

Controlling viscosity in bicomponent melt spinning is crucial for ensuring spinnability and interfacial stability. However, the significant difference in viscosity between PPS and CoPET poses a challenge to establishing the CoPET‐PPS sea‐island melt spinning system. Herein, the viscosity of PPS is regulated by blending high melt index PPS with spinning grade PPS, resulting in a viscosity ratio of CoPET to PPS over 0.5, thereby demonstrating the good spinnability of the CoPET‐PPS spinning system. The mathematical models for velocity, shear rate, and pressure distribution of CoPET‐PPS melts within the sea‐island spinning assembly are developed using Polyflow software, providing theoretical analysis for sea‐island melt spinning. CoPET‐PPS sea‐island bicomponent fibers are successfully fabricated via the facile bicomponent melt spinning technique, guided by the results of capillary rheology and simulation analysis. In addition, the condensed state structure and mechanical properties of CoPET‐PPS sea‐island fibers are significantly enhanced with increasing draw ratios. This straightforward strategy, combined with experimental and numerical simulations, is anticipated to effectively improve the spinnability of multicomponent melt spinning, especially in cases of significant viscosity differences between polymers. Highlights The CoPET‐PPS spinning system was constructed by regulating PPS viscosity. The distribution of the CoPET‐PPS melt in the spinneret holes was simulated. CoPET‐PPS fibers were fabricated based on rheology and simulation results. The mechanical properties of CoPET‐PPS fibers improve with higher draw ratios. Bicomponent CoPET‐PPS sea‐island fibers were successfully fabricated with a distinct sea‐island two‐phase structure. The molecular orientation, crystallization, and tensile strength of the as‐prepared fibers significantly improved with increased draw ratios.