Rheological behavior of poly(acrylonitrile) concentrated solutions: effect of Sb2O3 nanoparticles on shear and extensional flow

This study investigates the effect of antimony trioxide (Sb2O3) nanoparticles on shear and extensional flow properties of concentrated polyacrylonitrile (PAN) solutions. Through shear rheology, a wide variety of rheological observations, such as Payne effect, applicability of Cox-Merz rule, and range of linear viscoelastic behavior (critical strain) were assessed. The presence of Sb2O3 nanoparticles was found to promote the non-linear viscoelasticity of the solutions and give rise to enhanced heterogeneous domains of PAN in the solution. In elongational flow, thinning dynamics of the nanocomposites was tracked to reproduce the dynamics of deformation in the spinline of the dry-jet wet spinning process. Increasing amounts of Sb2O3 nanoparticles in the solution were shown to improve the lifetime of the filament. All solutions were ruptured through elastocapillary behavior, while strengthened strain-hardening behavior was observed after the addition of Sb2O3 nanoparticles to the polymer solution.