Body Armour Procedure

introduction
The purpose of this scientific poster is to examine 2 different types of liquid body armour. Liquid body armour is protective clothing with liquid chemicals designed to strengthen it to absorb and/or deflect slashing, stabbing and penetrating attacks by weapons. The poster will discuss two different liquid used to strengthen kevlar (modern armour material). The first is a colloid of silicon dioxide particles suspended in polyethylene oxide. this liquid is a Shear thickening fluid which hardens on impact. the second liquid used is a magnetorheological (MR) fluid. MR fluids are oils that are filled with iron particles and can change its viscosity to a solid state when a magnetic field is applied to it. The third section of the poster
A STF is a fluid that will turn into a solid state when it encounters mechanical stress or shear. Once the STF encounters the shear it behaves like a solid for a few milliseconds. It then returns to a liquid state. (This contrasts with a shear-thinning fluid, like paint, which becomes thinner when it is agitated or shaken). The STF is a colloid, made of tiny particles suspended in a liquid. These particles repel each other slightly. This means that the particles float easily and evenly throughout the liquid without clumping together or settling to the bottom. But when a sudden impact or shear hits the liquid , the repulsive forces of the particles are overwhelmed and they stick together, forming masses called hydro clusters. When the energy from the impact dissipates, the particles begin to repel one another again and the hydro clusters fall apart and forms back into a liquid.(A common example of a STF is equal proportions of cornstarch and water). The shear thickening fluid used in liquid body armor is made of silicon dioxide (SiO2) particles suspended in polyethylene oxide (H−[O−CH2−CH2]n−OH). Silicon dioxide is found in sand and quartz, and polyethylene oxide is a polymer commonly used in laxatives and lubricants. When the body armour is being made, the STF is diluted in ethanol, then kevlar is saturated with the liquid and it is placed in an oven to evaporate the ethanol. The STF
MR fluids are oils that are filled with iron particles and can change its viscosity from a liquid to a solid state when a magnetic field is applied to it. MR fluid differs from ferrofluid, which contains ferromagnetic particles with a surfactant to inhibit clumping because it thickens when magnetized. The iron particles are surrounded by surfactants to help keep them suspended and to reduce the surface tension in the fluid. Although the particles are tiny, the magnetic field applied to it will dramatically change the viscosity of the fluid. The iron particles will usually be between 20 and 40 percent of the fluid. The use of MR fluid in body armour will greatly strengthen conventional armour. With the right combination of density, particle shape and field strength, MR fluid can change from a liquid to a very thick solid. As with shear-thickening fluid, this change could dramatically increase the strength of a piece of armor. The trick is activating the fluid's change of state. Since magnets large enough to affect an entire suit would be heavy and impractical to carry around, researchers propose creating tiny circuits running throughout the