The role of cold crystallization of homochiral crystallites in the superb heat resistant poly(lactic acid)

Abstract The superb heat resistance poly(lactic acid) (PLA) were prepared by blending PLA and poly( d ‐lactic acid) (PDLA) with various molecular weight ( M n ). Formation of the stereocomplex in the blends was confirmed by differential scanning calorimetry and wide‐angle X‐ray diffraction. The results of the heat resistance implied it is possible that elevating the Vicat penetration temperature of PLA up to 150°C by blending with PDLA. The cold crystallization of homochiral crystallites is proven to be the critical factor affecting the heat resistance of PLA. While the PLA or PLA/PDLA blends were heated to cold crystallization temperature of samples, both the crystal content and the rigid amorphous region content are increased due to the cold crystallization and tethering effect, and the stiffness and heat resistance of the sample are improved. The cold crystallization homochiral crystallites kinetics of PLA and PLA/PDLA blends was also studied. The results showed the activation energy (∆ E ) of cold crystallization increased from 120.30 kJ/mol to 144.66 kJ/mol with the increasing of PDLA content from 2% to 10%.