The invention discloses a method for preparing a high molecular weight vertical structure composite
polylactic acid with melt stability characteristics. The method comprises the following steps: firstly, carrying out
drying treatment on L-polylactide and dextral
polylactic acid in vacuum, and then mixing an initiator which can be completely dissolved into absolute ethyl
alcohol with a cross-linking agent, and then adding a mixture to a fusion mixer; melting and blending under the conditions that the temperature is 170-200 DEG C and the rotating speed is 20-120 rpm (
revolutions per minute) for 2-15 minutes. The prepared high molecular weight vertical structure composite
polylactic acid not only has excellent melt stability, but also has strong recrystallization ability, and can ensure that the vertical structure composite polylactic acid
crystal with high purity and high content is reformed in a molten product, so as to provide excellent
heat resistance and weather fastness to the product. The possibility is also provided for preparation of a PLA product with high performance by virtue of a melt
processing technology. Meanwhile, the preparation method provided by the invention is simple in process, high in efficiency, and easy for realization of large-scale industrial production.