An efficient, food contact accelerator for stereocomplexation of high-molecular-weight poly( -lactide)/ poly( -lactide) blend under nonisothermal crystallization

It is an effective strategy to improve the heat resistance of polylactide (PLA) via forming stereocomplex crystals (SCs) in poly( l -lactide) (PLLA)/poly( d -lactide) (PDLA) blend. In this work, pentearythritol (PENTA), which is an environment-friendly polyhydroxy compound for food packaging, is selected to facilitate the SC crystallization and suppress the HC crystallization for HMW PLLA/PDLA blend. Impressively, only 3 wt% PENTA is added, the exclusive SCs with high content (Xc,SC = 50%) can be obtained, which exhibits a high promotion efficiency of crystallization of SCs. Interestingly, with PENTA content ascending, the crystallinity of SCs increases drastically first and then in a relatively slow manner. Furthermore, Miscibility with high content of PENTA leads to a relatively looser packing of SC lamella in the blend confirmed by scanning electron microscope (SEM) due to intercalation of PENTA between crystal lamella. The mechanism of how PENTA facilitates the formation of SCs at molecular level is also proposed in this work.