Abstract
Kneading torque and apparent viscosity were investigated on several series of alumina-thermoplastic resin systems selected from six kinds of alumina and three kinds of resin. The curves of kneading torque vs time at 453K were classified into four patterns which were dependent on resin type and alumina grade. The change of the pattern was also brought about by the change of solid concentration in the same alumina-resin system. The torque after 1h showed a good correlation with the apparent viscosity measured at the same temperature by a capillary type viscosimeter. The apparent viscosity of alumina-polypropylene and -polystyrene systems at high solid concentrations of 50% and 60% was influenced by the tap or compaction density of powders much more than by their surface area or size. The relative compaction density was an excellent parameter to estimate the flow and kneading properties at high solid concentrations. The alumina-polyethylene system, however, behaved somewhat curiously, because the type of degradation of polyethylene caused by the mechanical and thermal mixing was different from that of polypropylene or polystyrene.
