High-toughness polylactic acid alloy and preparation method thereof

The invention discloses a high-toughness polylactic acid alloy and a preparation method thereof. The high-toughness polylactic acid alloy is prepared by carrying out melt blending reaction and extrusion on polylactic acid, unsaturated aliphatic polyester and free initiator, wherein the mass ratio of the polylactic acid to the unsaturated aliphatic polyester is 70:30-98:2, the free-radical initiator accounts for 0.01-1 wt% of the sum of polylactic acid and unsaturated aliphatic polyester, the tensile strength of the polylactic acid alloy is 35-64 MPa, the elongation at break is 32-373%, and the impact strength is 36-637 J/m. The high-toughness polylactic acid alloy can well improve the tensile toughness and impact toughness of the polylactic acid, can enhance the elongation at break to nearly 400% and can enhance the impact strength to nearly 640 J/m, thereby having important meanings for widening the application range of polylactic acid; and meanwhile, the high-toughness polylactic acid alloy has complete biodegradability, and thus, has favorable social benefit and economic benefit.