A Study on the Rheological Property and Dry‐Jet Wet Spinnability for Heterocyclic Aramid Liquid Crystal Solutions

ABSTRACT The poly(p‐phenylene‐benzimidazole‐terephthalamide) (PBIA) fiber was dissolved into concentrated sulfuric acid (H2SO4) to prepare a liquid crystal (LC) spinning solution, and the rheological characteristics as well as the dry‐jet wet spinnability were investigated. Results show that the PBIA/H2SO4 solution forms a nematic LC phase with a critical concentration of approximately 14 wt.%. A preliminary phase diagram was constructed based on the rheological viscosity–temperature results, providing insights into the phase transformation behavior of the PBIA LC solution. Further analysis of the LC solution in different phase states shows that the yield stress required for flow in the anisotropic solution is much lower than in the isotropic solution. LC domains are the main factor affecting the solution's heterogeneity and relaxation behavior. The solution at 18 wt.% was subsequently used for fiber preparation, and PBIA fibers were successfully fabricated via the dry‐jet wet spinning method, demonstrating the feasibility of this approach. The tensile strength and modulus of the as‐spun fibers reached 5.66 and 193.96 cN/dtex, respectively, indicating a substantial potential for further improvement. This work demonstrates the practicality of preparing PBIA fibers via LC spinning, which is highly significant for enhancing both the production efficiency and mechanical performance of PBIA fibers.