二軸スクリュ押出機におけるリアクティブプロセシングの流動解析
Flow Analysis for a Reactive Processing in a Twin Screw Extruder
福岡孝政・Kyonsuku Min
Fukuoka. Takamasa / Kyonsuku Min
A numerical technique was developed to simulate the flow with the peroxide controlled degradation of polypropylene in a modular non-intermeshing counter-rotating twin screw extruder. To take into account the reaction, the free radical reaction kinetic model which enables to predict the molecular weight distribution of degraded polypropylenes was employed. Introducing several approximations into the Cross model, a rheo-kinetic equation was established on the empirical data, in order to describe the effect of molecular weight and its distribution on the shear viscosity. The flow analysis network (FAN) was used for the non-isothermal flow of non-Newtonian fluid in the twin screw extruder. The conservative equations including the energy and chemical species were solved with an iterative method calculating along reversed streamlines. Through a series of computations, the profiles of peroxide concentration, molecular weight and polydispersity of the polypropylene in a flow field were obtained as well as the profiles of pressure, shear viscosity, temperature and residence time. A simulation representing these scalar parameters seemed to be uniform in each screw region whereas they were mixed in the intermesh region of the twin screw extruder. In conclusion, the evaluation of screw characteristics was important to optimize the design of extruders and operating conditions for reactive extrusions.
Key words: Reactive processing / Controlled degraded polypropylene / Twin screw extruder / Flow analysis network method