Influence of Silica Concentration, Dispersion Energy and Humidity on the Stability of Shear Thickening Fluids
Shear thickening fluids are materials that show sharp increases in viscosity when undergoing critical stresses. These materials are good alternatives to improve applications where energy dissipation is important, for example, in the fabrication of liquid body armor and shock absorbing protective gear. However, new applications depend on the development of strategies to confine shear thickening fluids, so they can be handled more easily. One possibility is the combination of elastomers with these fluids, resulting in flexible yet highly impact absorbing materials. The goal of this research project is to develop effective ways to produce a combination of SEBS thermoplastic elastomers with shear thickening fluids, in which the properties of the fluid are preserved in order to increase the impact absorption of the thermoplastic elastomer. Shear thickening fluids were successfully obtained by mixing polyethyleneglycol (PEG) with silica nanoparticles in solution with the aid of ultrasound. The stability of the shear thickening properties was assessed by rheological tests as a function of time and other parameters. The blending of shear thickening fluids with SEBS was made by toluene solution casting. Preliminary results showed that producing such materials by toluene solution was not effective, due to the fact that the presence of the solvent impaired the shear thickening properties. Thermomechanical processesing was not effective either, because of the temperatures used during SEBS forming can modify the properties of the shear thickening fluid. Nevertheless, mixtures of SEBS in powder form with shear thickening fluids resulted in a material with high increase in its capacity to dissipate energy compared to the raw material, which shows that the addition of shear thickening fluids is effective to improve impact absorbance.