RHEOLOGICAL BEHAVIOR OF A POLYMER-CERAMIC BLEND

The rheological behaviour of an alumina injection moulding suspension was studied. A capillary rheometer allowing working under accurate inj ection moulding conditions has been developed. The main result concern s the observed slip phenomenon. It was shown that wall slip is reinfor ced with higher temperatures and decreasing shear rates. An attempt wa s made to correlate the results of the rheological study with the emer gence of injection moulding defects. Normal filling was observed at lo w temperature, but solid jetting appeared under high temperatures and low shear rates. This unusual behaviour is a consequence of the wall s lip mechanism. At low temperatures, when no slip was detected on rheol ogical measurement, a steady front flow takes place. At higher tempera tures, wall slip is favoured to shearing and unsteady front flow is ob tained. (C) 1996 Published by Elsevier Science Limited.