Enhanced dynamic impact resistance of UHMWPE fabrics impregnated with double-thickening shear thickening fluid

Inspired by the thermal stability mechanism of thermophilic protein, which presents ionic bonds that have better stability at higher temperatures, this paper proposes the introduction of electrostatic interactions by adding carboxyl-modified silica (C-SiO₂), PAA, and CaCl₂ to achieve higher viscosity over 25 °C. The rheological behavior of C-SiO₂-based shear thickening fluid (CS-STF) was investigated at a temperature range of 25–55 °C. Unlike SiO₂-based STF, which exhibits single-step thickening and a negative correlation between viscosity and temperature. As the C-SiO₂ content was 41% (w/w) and the mass ratio of PAA:CaCl₂:C-SiO₂ was 3:1:10, the CS-STF displayed a double-thickening behavior, and the peak viscosity reached 1330 Pa·s at 35 °C. From the yarn pull-out test, the inter-yarn force was significantly increased with the increasing CS-STF content. Treating UHMWPE fabrics with CS-STF improved the impact resistance effectively. In the blunt impact test, the U-CS fabrics with high CS-STF content (121.45 wt%) experienced penetration failure under high impact energy (18 J) due to stress concentration caused by the shear thickening behavior. The knife stabbing test demonstrated that U-CS fabrics with appropriate content (88.38 wt%) have the best stabbing resistance in various impact energies. Overall, this study proposed a high-performence STF showing double-thickening and enhancing shear-thickening behavior at a wide temperature range, the composite fabrics with the performance of resisting both the blunt and stab impact had broad application prospects in the field of personal protection.