Novel Kevlar fabric composite for multifunctional soft body armor

Besides resistance to stab and impact, good flexibility and lightweight, soft body armors are also desired to have capabilities of monitoring human physical state, maintaining body temperature, and being nonflammable. In this work, a three-coaxial-layer fabric composite with Kevlar fabric as a core protection layer, reduced graphene oxide (RGO) and nano-SiO2/shear-thickening gel (STG) as functional layers is developed with the above-mentioned features for multifunctional soft body armors. The as-prepared SiO2/STG/RGO@Kevlar (SSG@Kevlar) fabric composite has excellent electro-heating performance under a low work voltage of 5 V, an extraordinary strain sensing ability (gauge factor over 41, outstanding linearity (R2 > 0.99), a fast response (69 ms), high strain resolution (0.05%)) and an effective impact energy sensing ability. Benefited from the introduction of SiO2/STG layer, the SSG@Kevlar fabric composite also exhibits an obviously enhanced anti-impact performance (a peak force reduction of 40%) and a significantly improved knife-stab resistance (a penetration depth reduction of 12 mm), due to the shear thickening effect of STG and the yarn interaction force enhancement caused by SiO2 nanoparticles. Furthermore, the SSG@Kevlar fabric composite offers remarkable fire-resistance, no open flame and glowing observed under continuous ignition due to the dense char formed. Consequently, the SSG@Kevlar fabric composite developed is promising for multifunctional soft body armors for protecting wearers in various aspects.