Rheology of composite filling material pastes

The rheology of composite pastes in the unset state has been studied using a cone and plate viscometer. All materials behaved as Bingham bodies, exhibiting linear shear stress-shear rate plots, with a positive shear-stress intercept (the yield stress of the material). The shape of the plot gave the coefficient of viscosity of the material; at sufficiently high shear rates, shear failure occurred, marked by a breakdown of the linear relationship. The materials studied gave a very wide range of the various rheological factors.