Crystallization behavior of biodegradable poly(L-lactic acid) (PLLA)/poly(butylene succinate) (PBS) blends based on in situ simultaneous wide-angle x-ray diffraction/small-angle x-ray scattering techniques and thermal analyses

Crystalline behavior of poly(L-lactic acid) (PLLA), polybutylene succinate (PBS) and their (PLLA/PBS) blends were investigated using differential scanning calorimetry, dynamic viscoelastic property, in situ simultaneous small-angle X-day scattering (SAXS)/wide-angle X-ray diffraction (WAXD) measurements, and scanning electron microscopic observation. The films of PLLA, PBS and (PLLA/PBS) blends with the various weight ratios were prepared by quenching from the molten phase, and then, various measurements were conducted during the crystallization process. Dynamic viscoelastic measurement revealed that the temperature, at which the crystallization of PLLA occurs, shifted to lower temperature side with an increase in the PBS ratio. Furthermore, in situ SAXS/WAXD measurements revealed that the crystallization rate of PLLA increased with blending PBS and crystallization of PBS was almost restricted by blending PLLA although homo PBS was partially crystallized even by quenching from the molten phase due to quite rapid crystallization rate of PBS. These phenomena are due mainly to the molecular dispersed state of PLLA and PBS components formed in the molten state. The results obtained in this study are quite useful to control mechanical properties as well as the crystalline state including crystallinity and melting temperature, and crystal lattice, for PLLA/PBS blend.