Rheological properties of PA6 chips with different spinnability in high-speed spinning

In view of the significant differences in spinnability, BASF PA6 chips (BASF, Germany, stable in high-speed spinning) and domestic PA6 chips (GC, China, unstable in high-speed spinning) were employed. The screw extrusion process of PA6 melt in high-speed spinning was simulated by capillary rheometer, with the aid of which shear rheology and extensional rheology of PA6 chips were both investigated deeply. To determine suitable and reliable experimental conditions, the influencing factors including moisture of PA6 chips, capillary disassembly and experiment repeatability on rheological results were also discussed. The moisture of PA6 chips is confirmed to be a crucial factor and the shear viscosity and extensional viscosity of GC chips are both greater than that of BASF chips. Moreover, the shear viscosity of GC chips increases with the extension of melting time, while that of BASF chips is basically unchanged, showing good spinnability in high-speed spinning.