Thermoforming of PLA-based articles

A method for producing a shaped article, comprising:

• heating a sheet of crystallizable polylactic acid (PLA)-based resin having a ratio of cold crystallization over total melting enthalpy (ΔHcc/ΔHm) greater than 0.7 as determined by differential scanning calorimetry (DSC), wherein the heating comprises a preheating step prior to a heating step, wherein
• in the preheating step, the sheet is subjected to heating to a temperature from at least 40° C. to at most 80° C. and
• in the heating step, the sheet is heated from a surface temperature of at most 80° C. to a surface temperature of at least 90° C. to at most 150° C. at a heating rate of 5° C. to 25° C. per second,
• to provide a heated sheet having a ratio of cold crystallization over total melting enthalpy (ΔHcc/ΔHm) greater than 0.6 as determined by DSC;
• and, immediately after the heating,
• forming the heated sheet to provide a shaped article by means of a mold, wherein the mold has a temperature of from 70° C. to 85° C.

A method for producing a shaped article, comprising:

• -heating a sheet of crystallizable polylactic acid (PLA)-based resin having a ratio of cold crystallization over total melting enthalpy (ΔHcc/ΔHm) greater than 0.7 as determined by differential scanning calorimetry (DSC), wherein the heating comprises a preheating step prior to a heating step, wherein
• in the preheating step, the sheet is subjected to heating to a temperature from at least 40° C. to at most 80° C.,
• in the heating step, the sheet is heated from a surface temperature of at most 80° C. to a surface temperature of at least 115° C. to at most 150° C. at a heating rate of 5° C. to 25° C. per second, to provide a heated sheet having a ratio of cold crystallization over total melting enthalpy (ΔHcc/ΔHm) greater than 0.6 as determined by DSC;
• and, immediately after the heating,
• forming the heated sheet to provide a shaped article by means of a mold, wherein the mold has a temperature of at least 70° C. and at most 120° C.