Abstract
Shear thickening fluid (STF) occurs in dispersions of highly condensed colloid particles and is categorized as a non-Newtonian fluid whose viscosity increases under shear loading which makes them beneficial in protective and impact resistance applications. The aim of this study is to synthesis two different STFs and characterize their microstructural properties to provide a data base for comparing the final macrobehavior of the two fluids under mechanical testing. Therefore, fumed silica and polyethylene glycol STF and starch with water STF-based dispersions were prepared. The particle size, zeta potential, SEM micrographs, and rheological analysis were performed for each type of STF. The effect of filler concentration was observed by using 10–30 weight% filling material. The rheological properties of STFs show higher viscosity measurements at same shear rates for starch/water STF than silica/PEG with maximum viscosity reaching 523.6 Pa s and 178.9 Pa s, respectively. Larger starch particle size over silica recorded as 303.7 nm and 16.49 nm, respectively, and zeta potential analysis recorded particle electrostatic charges as 22.6 mV and 12.8 mV, respectively, leading to more dispersion stability and obvious thickening effect at higher particle concentration leading to greater jump in viscosity at sudden shear rate. The results indicate the capability of trying more protective applications with more flexibility and less thickness when STF is implemented and a good database for the fluids to choose from according to their behavior.
Highlights
Shear thickening fluids (STFs) represent a subset of certain fluids that exhibit non-Newtonian fluid behavior with abrupt changes in viscosity at a particular shear intensity
E general objective of this study is to investigate the effect of colloid particle concentration of two prepared shear thickening fluid (STF) on rheology to understand the thickening phenomena based on the differences on the microscale. e research will develop different STF multisystems: one composed of silica and polyethylene glycol and the other one is starch and water. e research will provide a primary comparison between the properties of the prepared STFs while comparing their rheology, particle size, zeta potential, and Scanning Electron Microscope (SEM) images of the particles. e attained results will acquire the designer of the STF applications to choose among the suitable fluid system based on the final properties of the fluid
Particle Size Determination. e average particle size of the used fumed silica nanoparticles and starch is determined using Zetasizer Nano ZS operating using the dynamic light scattering (DLS) technique. e concentration of particles used in the DLS experiments is sufficiently low to exclude any possible effect of the concentration on the measurement
Summary
Shear thickening fluids (STFs) represent a subset of certain fluids that exhibit non-Newtonian fluid behavior with abrupt changes in viscosity at a particular shear intensity. Contact networks have the ability to resist the applied shear forces, and by means of this, suspension introduces viscosity growth and development of yield stress At this point, it should be noted that the key contribution to the rise in viscosity stems from interparticle contacts rather than hydrodynamic interactions and the process functions in a manner where particle attraction only induces contact network formation; these expanded branch-like structures are immune to shear. E true character of the shear thickening depends on the physical parameters of the suspended phase: the fraction of the particle, particle size and distribution, particle structure, and suspended phase Most carrier fluids such as water, ethylene glycol (EG), and polyethylene glycol (PEG) are commonly utilized. Prepared samples with various weight fractions of fillers were fixed for both systems at concentrations 10, 20, and 30% weight to weight for the rheological tests. e final results of the rheological test illustrate in logarithmic plots the viscosity range against the change in shear rate applied
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