Rheological and Spinnability Optimization of Sericin‐Graft‐Polyacrylonitrile Solution via Box–Behnken Response Surface Methodology

Sericin‐graft‐polyacrylonitrile (SS‐g‐PAN), synthesized by grafting acrylonitrile monomers onto sericin, integrates the flexibility of natural sericin with the structural framework of polyacrylonitrile (PAN), representing a promising sustainable fiber material. However, the relationship between its solution composition and spinnability has not yet been fully elucidated. In this study, Box–Behnken response surface methodology was employed to optimize the preparation conditions of SS‐g‐PAN solutions and to investigate their rheological behavior and spinnability. The effects of sericin content, solid content, and initiator concentration on zero‐shear viscosity, structural viscosity index, characteristic relaxation time, and critical draw ratio were systematically evaluated. The optimized conditions were determined as sericin content of 33.30 wt%, solid content of 14.65 wt%, and initiator concentration of 0.71 wt%. The optimized SS‐g‐PAN fibers were compared with conventional PAN fibers. Results showed that sericin incorporation reduced fiber rigidity, while raising the glass transition temperature, as grafted sericin segments imposed steric hindrance restricting PAN chain mobility. Notably, the toughness increased significantly from 23.09 ± 8.08 to 104.31 ± 12.11 cN/dtex, with only a slight reduction in tensile strength. This approach partially replaces petroleum‐based materials with sericin, providing a feasible theoretical foundation and technical reference for the development of sericin‐based fibers without compromising their processability.