Rheological properties and stability of shear thickening fluids based on silica and polypropylene glycol

Rheological behavior and structural stability of shear thickening fluids (STFs) based on amorphous silica KE-P50 (500-600 nm) and polypropylene glycol, with molar mass 2000 g mol(-1), were studied. The static and dynamic rheological measurements were performed using rheometer ARES and stability tests were carried out using the static multiple light scattering (S-MLS) method. The preliminary tests were performed for the STFs having 50-55 vol% of silica and the detailed studies were carried out for two fluids, with 50 and 53 vol% of silica, respectively. All the STFs studied exhibit shear thickening properties. Both, the zero-shear-viscosities and maximal viscosities increase with growing silica content. For the shear rates studied the viscous component of the shear modulus dominates over the elastic one. S-MLS tests showed that both the suspensions studied exhibit excellent stability over the 8 days of the test. The synthesized STFs can be used as a component of flexible energy absorbing and protecting structures.