Study On A New Mixing Element And Screw Configuration In Intermeshing Co-Rotating Twin Screw Extruder

FTX polygon is a new type of screw element which is invented to meet the higher speed and efficiency development in co-rotating twin-screw extruder. In order to know the performances of this element, the authors have studied its geometry and flow field. Firstly, FTX polygon is designed according to geometry of fully wiped twin-screw equipment. Then, A three dimensional flow field simulation of FTX polygon is carried out by the ANSYS FEM package. Pressure profile, velocity profile and viscosity profile are obtained. Post-processing program is developed to calculate throughput, backflow ratio, shear rate and shear stress. The mixing ability of FTX polygon is also analyzed. A comparison is made between the flow fields of FTX polygon and kneading block under the same condition. The results are: each parameter in FTX polygon distributed more uniformly than that in kneading block, FTX polygon has more output than kneading block with the same pressure difference, dispersive mixing ability of FTX polygon is equivalent to that of kneading block.Gear disk and screw bushing can be used in co-rotating twin-screw extruder in different manners. In order to learn which screw configuration can get the best mixing capability, flow fields of gear disk plus screw bushing which are arrayed in different manners are studied. Pressure field, velocity field and viscosity field are calculated. The mixing ability of different flow fields is compared. The result can be concluded that several short mixing zones have better mixing ability than a whole long mixing zone.Finally, experiments are performed to testify the flow field simulation results of FTX polygon. It proved that the flow field simulation with ANSYS is feasible. The results show that FTX polygon consumes less energy, the temperature of the polymer is lower at the exit of the extruder and its mixing ability is better than kneading block. FTX polygon is suitable to process fiberglas reinforced modification. And some phenomena of polymer melting and flow in twin-screw extruder are observed.