The steady and dynamic rheological properties of hydroxyl-terminated polydimethylsiloxane filled with calcium carbonate were investigated by varying the filler volume fraction (Phi) from 0 to 18.2 vol %. The results reveal that there exists a "percolation threshold" (Phi(c) = 3.6%) for the suspensions, below which both the "Cox-Merz" and modified "Cox-Merz" rule are competent over the whole shear regions. However, these two rules breakdown and a characteristic plateau appears in low frequency regions for suspensions with Phi > Phi(c). The reasons for this can be ascribed to the contributions of nonhydro-dynamic forces and formation of percolated filler network structure with increasing Phi. Moreover, using a concentration-dependent parameter, B(Phi), superposition curves of dynamic complex modulus (vertical bar G*vertical bar) and shear stress (tau) for all suspensions were obtained through shifting vertical bar G*vertical bar curves along the ordinate and T functions along the abscissa using different B(Phi) as shifting factor. Unfortunately, the reasonable superposition range is restricted in the high omega or gamma regions. (c) 2007 Wiley Periodicals, Inc.