Polyurethane-Kevlar composite porous film and preparation method thereof

The invention provides a polyurethane-Kevlar composite porous film and a preparation method thereof, and the method comprises the following steps: respectively preparing a polyurethane solution and a Kevlar nanofiber dispersion liquid with preset concentrations, then mixing the polyurethane solution and the Kevlar nanofiber dispersion liquid, and sequentially carrying out coating, demolding, solvent exchange and freeze drying to prepare the composite porous film. Kevlar fibers are degraded by a specific process, an obtained Kevlar nanofiber dispersion liquid is mixed with a polyurethane solution, and Kevlar molecules bonded on a polyurethane molecular chain are continuously changed through specific coagulating bath, solvent composition, two times of solvent exchange and freeze drying, so that the Kevlar nanofibers are obtained. Meanwhile, the bonding and intertwining degrees among different polyurethane molecular chains are continuously changed, and finally the high-performance polyurethane-Kevlar composite p