オーバル形混練機における高分子材料の未溶融固着層の挙動解析

抄録

In order to perform a behavior analysis of polymeric material in a mixer with ovalor wing-type rotors, it was necessary to find a theoretical solution to the movement of an unmelted material layer. This layer, which appeared on to the rotor surface during the initial mixing period, was distinguished from the melt layer by a well-defined boundary. Photographs of material flow during various mixing stages of low-density polyethylene(LDPE) in a single-rotor mixer showed that the umelted layer moved along the rotor surface in the direction away from the tip region and finally broke at the end of the melt pool. This was previously referred to as the “breaking phenomenon.” The motion of the secondary flow boundary point, which is the separation point of the flow from the rotor surface, was analyzed using an assumed temperature distribution for the behavior model. The result agreed well with the actual movement of the unmelted layer. The result of model calculation indicates that the unmelted layer is the secondary flow region at the front face of the oval-type mixer. The breaking causes the undispersed, low-temperature material of the un-melted layer to flow into the melt layer and this gradually passes through the tip region of the rotor. During this passing period, the required torque increased even in the mixing of LDPE. Thus, it became more necessary to determine if this phenomenon corresponds to the second torque peak phenomenon which had been reported by many researchers for polymers containing large quantities of agglomerate particle additives such as carbon black.