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Solid-state microstructures, thermal properties, and crystallization of biodegradable poly(butylene succinate) (PBS)
Z Gan1, H Abe, H Kurokawa
1Polymer Chemistry Laboratory, RIKEN Institute, Hirosawa 2-1, Wako-shi, Saitama 351-0198, Japan.
Biomacromolecules
|December 26, 2001
Summary
This study investigates biodegradable poly(butylene succinate) (PBS) copolyesters, revealing that comonomers influence amorphous thickness but not crystal structure. The Gibbs-Thomson equation proves more reliable for determining melting temperatures in these complex materials.
Area of Science:
- Materials Science
- Polymer Chemistry
- Crystallography
Background:
- Biodegradable aliphatic poly(butylene succinate) (PBS) and its random copolyesters are crucial for sustainable materials.
- Understanding their solid-state structures, melting behavior, and crystallization kinetics is essential for material design.
- The influence of comonomer incorporation on PBS properties requires detailed investigation.
Purpose of the Study:
- To analyze the solid-state structures, melting behavior, and crystal growth kinetics of PBS and its random copolyesters with ethylene succinate (ES) and hexamethylene succinate (HS) units.
- To elucidate the role of ES and HS comonomers in the crystalline and amorphous phases of PBS.
- To determine and compare the equilibrium melting temperatures and analyze crystal growth kinetics using established thermodynamic and kinetic models.
Main Methods:
- Wide-angle X-ray diffraction (WAXD) to determine crystal structures.
- Small-angle X-ray scattering (SAXS) to analyze crystalline and amorphous phase structures and sizes.
- Gibbs-Thomson and Hoffman-Weeks equations for equilibrium melting temperature (T(m)(0)) determination.
- Secondary nucleation theory to analyze crystal growth kinetics.
Main Results:
- Crystallographic analysis showed ES and HS units are excluded from the crystalline core, residing in the amorphous phase.
- SAXS revealed that comonomers increase amorphous layer thickness, but their influence on lamellar structure and size is complex.
- The Gibbs-Thomson equation indicated P(BS-co-15 mol %HS) has a similar T(m)(0) to PBS, while P(BS-co-14 mol %ES) has a lower T(m)(0), suggesting its greater impact on crystalline phase structure.
Conclusions:
- Comonomer incorporation in PBS primarily affects the amorphous phase, with minimal impact on the crystalline structure.
- The Gibbs-Thomson equation is deemed more reliable for determining the equilibrium melting temperature of these copolyesters.
- Crystal growth kinetics analysis revealed interrelations between regime transition temperature and melting behavior, influenced by comonomer type and concentration.