Effect of thermal annealing on crystal evolution and multiple melting behaviors of molded poly(L-lactic acid) and poly(butylene succinate) blends upon heating investigated by TMDSC

The influence of post-process annealing treatment on the structural and thermal behaviors of poly(L-lactic acid)/poly(butylene succinate) (PLLA/PBS) blend was investigated by temperature modulated differential scanning calorimetry (TMDSC) and wide-angle X-ray diffractometry. It is shown that the low-order alpha '-structure of PLLA was formed in the as-molded samples and the molded products annealed at the temperatures below the melting of PBS, whereas the high-order alpha-crystal was developed when the high temperature of annealing (152 degrees C) was applied. With the addition of poly(ethylene glycol) plasticizer to the blends, the formation of high-order alpha-structure was prohibited. During the DSC heating scan, the alpha '- to alpha-crystalline phase transformation did not occur. The evidence of multiple melting behaviors observed by TMDSC was ascribed to the simultaneous melting, recrystallization, and remelting of the PLLA and PBS crystals in the blends.

Automated summary

The influence of post-process annealing treatment on the structural and thermal behaviors of poly(L-lactic acid)/poly(butylene succinate) (PLLA/PBS) blend was investigated. It was found that the temperature and addition of plasticizer can significantly affect the crystalline structure and melting behavior of the samples. Multiple melting behaviors observed were attributed to simultaneous melting, recrystallization, and remelting of PLLA and PBS crystals in the blends.