Systematic Conditions Optimization of Kilometer-Scale Aramid Fiber with High Tensile Strength via Microfluidic Spinning

Abstract Poly(p-phenylene benzimidazole-benzamide) (PBIA) fiber, with superior mechanical properties, has become a promising chemically synthesized high-performance aramid fiber. The crystallization and orientation behaviors of PBIA fiber critically determine its comprehensive properties but remain highly sensitive to fiber processing conditions. In this work, we systematically investigate the effects of key fiber processing conditions on the crystallinity, orientation, and mechanical properties of PBIA fiber, such as monomer molar ratio, spinning dope rheology, coagulation bath composition and temperature, draw ratio, and heat treatment conditions. Under optimal fiber processing conditions, kilometer-scale PBIA fiber with high tensile strength (4.75 GPa) is continuously and stably fabricated by microfluidic spinning because of its high crystallinity (12.8%), orientation (0.904), and ultralow misorientation angle (5.214°). This systematic optimization of conditions via microfluidic spinning provides a viable and attractive pathway for the industrial-scale production of high-performance PBIA fiber.