Abstract
Stereocomplex-polylactic acid (SC-PLA) is obtained in poly(d-lactic) acid/poly(l-lactic) acid (PDLA/PLLA) blends under adjusting processing conditions. It is found that the degree of crystallinity of overall SC-PLA is up to 43.7% in PDLA/PLLA blends of 1:1 mass ratio. Formation of stereocomplex (SC) crystals forces molecular chains in the blends to be more closely arranged and further enhances interaction between molecular chains, thus forming a physical cross-linking network in the SC crystals, resulting in the blends having a special microstructure. The mechanism of formation of the SC crystal physical cross-linking network is elucidated by dielectric spectroscopy, and the relationships between homocomplex (HC) crystals, SC crystals, and amorphous regions in the blends are also analyzed. Interestingly, mechanical properties of the blends are significantly improved due to formation of an SC crystal cross-linking network.
Highlights
In recent years, increasing consumption of petroleum-based materials and production of plastic waste has resulted in severe environmental pollution, and addressing this issue is critical
Compared with poly(l-lactic) acid (PLLA) and/or poly(d-lactic) acid (PDLA), stereocomplex-polylactic acid (SC-Polylactic acid (PLA)) has a higher melting point of 210–230 ◦ C, and its mechanical properties, e.g., thermal stability, are significantly improved. This is because the two isomers (PDLA and PLLA) are in the form of complementary helical structures in SC-PLA, and the unique hydrogen bond (C=O . . . H3 C) and dipole–dipole interaction between the two isomers optimizes the properties of SC-PLA [6]
Extruded PDLA/PLLA blends were cooled to room temperature (20 ◦ C) and a sample was cut into particles using an electrically controlled granulator (JD1A-90, LvDao Ltd., Suzhou, China)
Summary
In recent years, increasing consumption of petroleum-based materials and production of plastic waste has resulted in severe environmental pollution, and addressing this issue is critical. Compared with PLLA and/or PDLA, SC-PLA has a higher melting point of 210–230 ◦ C, and its mechanical properties, e.g., thermal stability, are significantly improved. This is because the two isomers (PDLA and PLLA) are in the form of complementary helical structures in SC-PLA, and the unique hydrogen bond Study of internal structures and crystallization behaviors of the materials by broadband dielectric spectroscopy, a popular characterization method, has been extensively reported in recent years. The microstructure, crystallization behavior, and dielectric and mechanical properties of the PDLA/PLLA blends were investigated and the mechanism of the formation of SC crystals was educed
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
