Abstract: Some embodiments of the present invention provides a method of preparing a thermoformed article composed of polylactic acid that includes the steps of providing a foam sheet comprising polylactic acid having a D-lactic acid stereo-isomer content that is about 3 mole % or less, exposing the sheet to a temperature of at least about 190° C., and forming the heated sheet in a mold at a mold temperature that is at least about 50° C. and for a length of time to form a thermoformed article having a PLA crystalline content of at least about 10%. Surprisingly, it has been discovered that heat resistant thermoformed articles can be prepared in accordance with embodiments of the invention wherein the time required for forming the foam sheet into a molded article is less than about 10 seconds.

Abstract: Some embodiments of the present invention provides a method of preparing a thermoformed article composed of polylactic acid that includes the steps of providing a foam sheet comprising polylactic acid having a D-lactic acid stereo-isomer content that is about 3 mole % or less, exposing the sheet to a temperature of at least about 190° C., and forming the heated sheet in a mold at a mold temperature that is at least about 50° C. and for a length of time to form a thermoformed article having a PLA crystalline content of at least about 10%. Surprisingly, it has been discovered that heat resistant thermoformed articles can be prepared in accordance with embodiments of the invention wherein the time required for forming the foam sheet into a molded article is less than about 10 seconds.

Abstract: A foam precursor mixture of polylactic acid (PLA) resin having a D-lactic acid content that is about 3 mole % or less; nucleating agent; chain extender; and hydrocarbon blowing agent is provided. The foaming mixture is substantially free of a crosslinking agent. The foam premixture can be used to prepare PLA foams having improved heat resistance, lower densities, smaller cells, and higher cell counts. PLA foams in accordance with the invention may be useful for preparing thermoformed articles such as trays. PLA foamed articles may be prepared that exhibit heat resistance above a temperature of about 49° C. or more, and in particular, a heat resistance at 5 minutes of exposure in excess of about 74° C.