Suspensions of silica nanoparticles showed shear-thickening profiles under steady shear conditions up on addition of a small amount of poly(ethylene oxide) (PEO). The suspensions turned into gels upon shaking and thei...Suspensions of silica nanoparticles showed shear-thickening profiles under steady shear conditions up on addition of a small amount of poly(ethylene oxide) (PEO). The suspensions turned into gels upon shaking and their fluidity was recovered several minutes after resting. We studied the rheological properties of these shake gels with small amounts of sodium chloride (NaCl). Gelation occurred at lower shear rates upon addition of small amounts of NaCl. In addition, the time taken by the gelated samples to recover their original viscosity increased with the increasing NaCl content. The weakened repulsive interactions between the silica particles upon NaCl addition lead to particles in closer proximity, and three-dimensional networks of PEO chains are easily formed as the electric double layer of the particles becomes thinner.展开更多
文摘Suspensions of silica nanoparticles showed shear-thickening profiles under steady shear conditions up on addition of a small amount of poly(ethylene oxide) (PEO). The suspensions turned into gels upon shaking and their fluidity was recovered several minutes after resting. We studied the rheological properties of these shake gels with small amounts of sodium chloride (NaCl). Gelation occurred at lower shear rates upon addition of small amounts of NaCl. In addition, the time taken by the gelated samples to recover their original viscosity increased with the increasing NaCl content. The weakened repulsive interactions between the silica particles upon NaCl addition lead to particles in closer proximity, and three-dimensional networks of PEO chains are easily formed as the electric double layer of the particles becomes thinner.
