Executive Summary : | Shear thickening fluids (STF) are dense colloidal dispersions that increase resistance to flow with an increase in stress/strain-rate level. They are ideal for soft body armor applications due to their reversible and repeatable liquid-to-solid transition. Wagner's group made a significant contribution in this field in the early 2000s, demonstrating improved impact resistance of Kevlar fabrics upon STF impregnation. However, impregnation technique has limitations, such as wettability issues, mass-transfer resistance due to fabric porousness, uneven distribution of STF, and potential removal of STF from impact locations. A promising alternative is droplet-in-fibre structure, where liquid droplets are encapsulated within the fiber using microfluidics integrated with fibre-spinning technique. This structure has been explored for life science, food, and materials science applications. The proposed work aims to fabricate such a structure by entrapping STF droplets within ballistic fibres for soft body armor applications. The work introduces two novel fabrication techniques based on thermal wet spinning and electrospinning to produce STF-embedded Polydimethysiloxane (PDMS) millifibres and microfibers. The concentrated dispersions of fumed silica in PEG400 or ionic liquid (IL) will be used as STF. The millifluidic setup will generate STF droplets continuously in liquid PDMS phase, which will be stretched through thermal wet spinning to produce STF droplet-embedded PDMS millifiber via in-situ curing. The STF-embedded fibers and fabrics will undergo tensile testing and knife impact resistance tests, with ballistic performance assessment as a future scope. |