Study on the volatilization behavior of monomer and oligomers in polyamide-6 melt by dynamic film–forming device

Abstract In this study, a modified torque rheometer is used to investigate the volatilization behavior of monomer and oligomers in polyamide-6 (PA6) melt under dynamic film–forming conditions with negative pressure. The surface renewal model is employed to simulate the volatilization behavior. The effects of actual processing factors and simulation results on the volatilization behavior of monomer and oligomer are analyzed comparatively. It is found that the monomer and oligomers removal rate increase continuously with increasing temperature, residence time, and rotational speed. And, the cyclic dimer, which is extremely harmful to spinning, can be removed. It is found that the removal of monomer and oligomers continued to increase with increasing temperature, residence time, and spinning speed. Moreover, cyclic dimers, which are extremely harmful to spinning, are also removed. Additionally, it is discovered that the polycondensation reaction of PA6 results in an increase in the molecular weight and viscosity at lower temperatures (250 °C), while a higher temperature (270 °C) and shear rate (150 r/min) cause a reduction in viscosity and molecular weight.