Tuning Rheological Property of Polyacrylonitrile Solution: Viscosity, Viscoelasticity, and Nonlinearity

ABSTRACT In the production process of carbon fibers (CF), the quality of PAN spinning solution (PANss) is one of the critical factors influencing the performance of CF. In this study, PANss with different mixed solvents were prepared, and its viscosity, linear and nonlinear rheological behavior were characterized by rheological measurement. The results demonstrated the PANss of this manuscript belong to non‐Newtonian fluids. The zero‐shear viscosity(η 0 ) decreased with the increase in lower‐viscosity solvent, while the index of flow (n) increased with the addition of the lower‐viscosity solvent, the variation in η 0 and n as a function of solvent content could be fitted using the equationy = a + b c x. Furthermore, the slope of log G″ versus log G′ increased with the increase in dimethylformamide (DMF) content in both PAN/dimethyl sulfoxide (DMSO): DMF spinning solution and PAN/dimethylacetamide (DMAC): DMF spinning solution. Conversely, the slope decreased as raised DMAC content in PAN/DMSO: DMAC spinning solution. Additionally, the degree of nonlinearity of the three types of PANss gradually decreased as the content of DMAC or DMF increased.