Differences Between Stereocomplex Spherulites Obtained in Equimolar and Non-Equimolar Poly(L-lactide)/Poly(D-lactide) Blends

✍ Scribed by Xiaohong Wang; Robert E. Prud'homme

• Publisher: John Wiley and Sons
• Year: 2011
• Tongue: English
• Weight: 1019 KB
• Volume: 212
• Category: Article
• ISSN: 1022-1352
• DOI: 10.1002/macp.201000704

✦ Synopsis

Abstract

PLLA/PDLA blends were crystallized between 120 and 195 °C. The stereocomplex spherulites acquired in equimolar and non‐equimolar blends were compared using POM, WAXD, DSC, and AFM. For equimolar blends, stereocomplex crystals show spherulites with positive birefringence, which is ascribed to the existence of domains made up of tangentially oriented lamellae. For PLLA‐rich (or PDLA‐rich) blends, the signs of the birefringence changed from a positive spherulite to a mixed spherulite and then to a negative spherulite. In negative spherulites, most lamellae orient radially. Radial and tangential cracks were observed in equimolar blends when crystallization took place above 175 °C whereas no cracks formed for non‐equimolar blends.
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