In the framework of a comprehensive study of the ceramic feedstocks in molten conditions, the viscoelastic behavior of zirconia-filled polymers has been studied over a broad span of particle concentrations (from 0 to 42 vol% i.e., from 0 to 82 wt%). This study shows that the effect of stearic acid on the melt rheology depends on the filler content, suggesting that different dispersion mechanisms of the fatty acid are involved and prevail over others, depending on the solid concentration. It is shown, for instance, that stearic acid lowers the percolation threshold and modifies the dispersion state. For the first time, the existence of two main regimes in terms of concentration ranges with different network structures is highlighted. The dispersion contributions are discussed for each regime by coupling SEM dispersion characterization, dynamic and steady rheological measurements. (C) 2017 Elsevier Ltd. All rights reserved.