Polyolefin polylactic acid polymer blends

The invention relates to a process of preparing a polyolefin polylactic acid polymer blend comprising the steps of i) providing a polyolefin selected from polyethylene, polypropylene, and mixtures and copolymers thereof, ii) providing polylactic acid, iii) providing a polyolefin selected from polyethylene, polypropylene, and mixtures and copolymers thereof grafted with at least one epoxide-functional monomer, iv) providing a polylactic acid grafted with at least one carboxylic acid or carboxylic anhydride functional monomer, v) mixing the components i) to iv) at elevated temperature in a range from 150° C. to 260° C., and wherein component i) is provided in an amount of 5.0 to 50.0% by weight, component ii) is provided in an amount of 40.0 to 90.0% by weight, component iii) is provided in an amount of 1.0 to 20.0% by weight, and component iv) is provided in an amount of 1.0 to 15.0% by weight, calculated on the sum of components i) to iv).