<p>To enhance the toughness of polylactic acid (PLA), poly(propylene carbonate) (PPC) was utilized to toughen it, and the effects of PPC dosage, type of chain extender, and dosage on the PLA/PPC blends were investigated. The results showed that the impact toughness of PLA/PPC blends was improved with the increase of PPC dosage, and the impact strength was improved by approximately 6.5 times compared with PLA when the PPC dosage was 40%. The addition of PPC decreased the apparent density and thermal stability of the PLA/PPC composite but improved the water contact angle and water absorption rate. The SEM analysis showed that the compatibility between PLA and PPC is not good and there are many holes between the interfaces. Three types of epoxy-based chain extenders were added, which could significantly improve the mechanical properties of PLA/PPC composites, with X-U993 at a lower dosage achieving the greatest improvement, while the pores in the surface morphology disappeared, which improved the interfacial compatibility. The FTIR analysis showed that the PLA and PPC were physically blended. TGA and DSC analyses showed that the addition of PPC decreased the thermal stability of the PLA/PPC blends, and after the addition of the chain extender, the thermal stability of the blends improved.</p> Graphical abstract <p></p>