Surface-modified aramid fiber and preparation method thereof

The invention discloses a surface-modified aramid fiber and a preparation method thereof. The preparation method comprises the steps that an aramid fiber with hydroxyl is immersed into a SiO2 colloid aqueous solution, after washing and drying are completed, the aramid fiber is immersed into MgAlFe layered bi-hydroxide suspension liquid, and after washing and drying are completed, a self-assembly cycle is completed on the surface of the aramid fiber, wherein in the self-assembly cycle, a layer of SiO2 negative charges serve as a first assembly, and a layer of MgAlFe layered bi-hydroxide nanosheet positive charges serve as a second assembly; repetitive operation is conducted, and multiple self-assembly cycles are completed, so that the surface-modified aramid fiber is obtained. The modified aramid fiber has the triple uvioresistant functions and is higher in heat resistance, high in mechanical performance and good in surface activity, the preparation process is green and environmentally friendly, the technology is easy to control, and the surface-modified aramid fiber and the preparation method thereof are suitable for large-scale production.