First, what is shear thickening fluid  

shear thickening fluid (hereinafter referred to as STF) is a mixed fluid formed by nanoparticles dispersed in polymers or long-chain polymer polymerization, using STF and polymer fiber materials to composite various types of advanced sports materials with excellent mechanical properties, so it has gradually become one of the most important materials in the field of external force protection, with broad application prospects.  

       The most typical application case of STF reinforced polymer fiber material in the early days can be traced back to the d3o material used by some ice and snow sports athletes at the 2006 Winter Olympics in Turin, which is normally relaxed, soft and elastic, and can provide athletes with good wearing comfort; once violently impacted by the outside world, the intermolecular particles lock each other, and the material hardens to form a tight protective layer to provide protection for athletes and reduce sports injuries.  

Second, shear thickening mechanism 

1.ODT principle  

ODT principle was first confirmed by Hoffman, who proved that the particles in the material system are improved when subjected to small external forces when subjected to small external forces by light scattering experiments on nanoparticle/polymer suspension system STF materials; when the external forces are larger, the ordered structure of particles is destroyed, thus showing the two phenomena of shear thinning and shear thickening, respectively.  

       2.Hydro-cluster theory(Hydro-cluster) 

When the distance between particles and particles decreases, the fluid lubrication increases. At high shear rates, fluid lubrication draws the particles closer together, and the aggregated particles form "clusters of water ions." Due to the high concentration of particles in the cluster, the stress on the fluid is large, and the flow between particles is difficult, resulting in an increase in energy dissipation rate and viscosity.

Third, the application of shear thickening materials

1. Sports protection  

 Many applications pay attention to the role of shear thickening liquid in sports equipment, and apply it in rackets, skis, footwear and other products, and have achieved remarkable results. Pictured below: Replacing the traditional belt of sports glasses with an STF-filled tubular belt that reduces injury by ensuring that personal protective equipment is kept in place in the event of an impact event. Prevents secondary impact injuries caused by eyewear falling off.

2. Protective outerwear  

 A certain racing sports protective outerwear fabric prepared by STF reinforced fiber material. The fabric mainly contains four layers of materials such as surface fabric, violent shunting material, violent absorption material and inner lining. Among them, the main raw material for the preparation of the violent absorbent material layer is STF reinforced fiber material, and when subjected to external impact forces, the violent shunt material can fully diffuse the impact of a point, and finally absorbed by stF reinforced fiber material.  

References 

[1] Zhang Jinqiu,Zhao Mingmei,Peng Zhizhao,Zhang Jian,Li Xin. Overview of theoretical basis and engineering application progress of shear thickening liquid[J/OL].Materials Review,2022(09):1-18[2021-11-22]. 

[2]Liu Jie. Research on the Development of Shear thickening liquid reinforced polymer fiber material fusion sports[J].Aging and Application of Synthetic Materials,2021,50(05):172-174. 

[3]Zong Hao,Wei Rubin,Dong Bin,Wang Xiaowei,Zhai Wen,Liu Zhongmin. Research Progress on Intelligent Composites of Shear Thickening Adhesive[J].New Chemical Materials,2021,49(04):52-56.