Polylactic acid stereocomplex compositions and methods for making and using same

摘要

Thermoformed PLA stereocomplex parts are made using a PLA stereocomplex composition having a highest crystallization melting temperature from 200 to 215° C. The stereocomplex composition preferably has less than 5 J/g of lower melting (160 to 190° C.) crystallites. The stereocomplex can be pre-annealed in various ways to reduce thermoforming cycle times. The stereocomplex forms parts with low haze and good thermal resistance, at reasonable cycle times.

主权项

1. A process comprising
a) forming a mixture of starting PLA resins in which a high D PLA resin constitutes from 25 to 75% by weight of the weight of the PLA resins and a high L PLA resin constitutes from 75 to 25% by weight of the PLA resins, and heating the mixture to a temperature above its highest crystalline melting temperature for a period of from about 5 minutes to 3 hours in the presence of a transesterification catalyst, and then blending the resulting transesterified PLA resins with an additional quantity of a high L PLA resin or high D PLA resin to form a blend provided that the proportions of PLA resins, including the starting PLA resins and the additional PLA resin, are such that a high D PLA resin and a high L PLA resin each constitute at least 25% of the PLA resins; then b) extruding the mixture to form a thermoformable sheet, and c) thermoforming the sheet.