Effect of ceramic nanopowders on rheology of thermoplastic suspensions

Rheological behaviour of thermoplastic polymer melts containing 20-50 vol.% of ceramic nanopowders was studied. For the preparation of thermoplastic polymer suspensions three ZrO2 powders with specific surface areas from 6.5 to 123 m2 g−1 were used. Using a capillary rheometer, viscous behaviour was examined in the temperature range from 100 to 150 °C and in the shear rate range from 100 to 1000 s−1. The viscosity of suspensions increased with increasing specific surface area of ceramic powder. The suspensions were of pseudoplastic nature, which was described by the power law. The power law exponent and the activation energy of viscous flow of suspensions decreased almost linearly with increasing specific surface area of the powder. The maximum volume fraction of the powder in the suspension also decreased with increasing specific surface area of the powder. The causes of the changes in viscous behaviour of the suspensions in dependence on the specific surface area of powders were discussed.