Viscosity effects in computer modeling of fiber spinning from crystallizing polymer
melts (in English)
Polimery 2004, No 2, 101
Role of local viscosity in the dynamics of melt spinning of a polymer crystallizing under tensile stress are investigated using mathematical modeling methods. The viscosity is assumed to be dependent on local temperature and degree of crystallinity along the spinning axis. Role of the polymer viscosity is studied for PET in the range from low to high spinning speeds. Strong effects of stress-induced crystallization on local polymer viscosity, resulting in crosslinking of chain molecules by arising crystallites, lead to limitation of the spinning speed, and a maximum of the take-up speed is predicted. Effects of the spinning-speed affected viscosity are analysed using simplified models of melt spinning and compared with the complete dynamic model. One concludes that the maximum of take-up speed predicted for high spinning speeds is a consequence of strong rheological effects of online oriented crystallization leading to gelation of the spun polymer by crystallites playing a role of physical crosslinks. Temperature effects on polymer viscosity are not responsible for the limitations of the take-up velocity.
Keywords: mathematical modeling of melt spinning, fiber spinning from crystallizing polymer melt, molecular orientation, oriented crystallization, viscosity of crystallizing polymer
Viscosity effects in computer modeling of fiber spinning from crystallizing polymer melts (in English)