Synthesis of Shear Thickening Fluid Using Sonochemical Method

摘要

The term shear thickening is typically used to refer to the increase in apparent viscosity when the applied shear rate is increased. The Shear Thickening Fluid (STF) is composed of hard metal oxide particles such as silica suspended in a polyethylene glycol liquid. The combination of flowable and hard components at a particular composition, results in a material with unusual properties. The STF is being developed at U.S. Army Research laboratory at Aberdeen providing grounds. When Kevlar or nylon woven fabric is impregnated with STF it demonstrates a significant enhancement in ballistic penetration resistance and the ballistic impact characteristics of the fabric without any loss in material flexibility. STF could be used in bomb blankets, and even jump boots, which could be made to stiffen upon impact to support the ankle. In the present study we report on preparation of STF using sonochemical method, where moister contamination is drastically reduced. The known weight percentage of silica nanoparticles and polyethylene glycol is dispersed in ethanol and irradiated with high power ultrasound for 5hours. The ethanol is completely removed by vacuum and heat. The resultant STF is tested for its rheological and thermal properties. The advantages and disadvantages of this process have been discussed and compared with the solvent exchange method which is currently used by the U.S. Army Research lab.