LAUSR

With various applicability of shear thickening fluids (STFs), control of rheological properties of STFs has been a major interest to industry. While carbon nanotubues and graphene have often been employed as fillers of STFs, little has been examined for their individual and combined effects on shear thickening behavior. In this study, the onset of viscosity increase of STFs was examined for the addition of: 1D functionalized multi-walled carbon nanotubes (fMWCNTs); 2D reduced graphene oxides (rGO); 3D network of MWCNTs-rGO hybrids (H); and spherical iron oxides (Fe3O4). To overcome the poor dispersibility of carbon particles, carbon nanotubes were functionalized to attach carboxylic groups (fMWCNTs), and graphene oxides (GOs) were reduced using TiO2 particles. Large hydrodynamic diameters of fMWCNT, rGO, and their hybrids of percolated network facilitated the interactions with silica particles in STF, decreasing the onset of shear thickening. Among the tested particles, STF with hybrids (H-STF) exhibited the lowest critical shear rate and the highest viscosity, due to the hybrid’s 3D network structure in which long and tortuous fMWCNTs bridged adjacent rGOs. The addition of Fe3O4 to HSTF shifted the shear thickening onset to a higher shear rate. The results demonstrate that the shear thickening onsets can be controlled by the selective additions of nanoparticles.