Preparation method of polylactic acid/nano-cellulose composite material

The invention provides a preparation method of a polylactic acid/nano cellulose composite material. The composite material comprises the following components in percentage by weight: 55 to 99.8% of polylactic acid, 0.1 to 15% of nano cellulose, and 0.1 to 30% of polyethylene glycol. The method comprises the following steps of: preparing a 5 to 15% an aqueous solution of microcrystalline cellulose, dripping concentrated sulfuric acid until the concentration of sulfuric acid reaches 40 to 60%, stirring and reacting for 1 to 2hours, carrying out centrifugation, ultrasound treatment and adjusting pH value to be neutral to obtain a nano cellulose suspension; dissolving polyethylene glycol, mixing with the nano cellulose suspension, stirring for 1 to 3hours at the temperature of 90 DEG C and carrying out vacuum drying to obtain a polyethylene glycol/nano cellulose comixture; and carrying out melt blending on the polyethylene glycol/nano cellulose comixture and polylactic acid for 5 to 8minutes at the temperature of 120 to 170 DEG C to obtain the composite material. The method is convenient and simple to operate, short in the time of the preparation process and solves the problem of uniform dispersion of nano-cellulose in the polylactic acid.