The Kinetics of Melting Crystallization of Poly-L-Lactide |
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| Authors: | Zhou Zhi-Hua Ruan Jian-Ming Zhou Zhong-Cheng Zou Jian-Peng |
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| Affiliation: | 1. State Key Laboratory for Powder Metallurgy , Central-South University , Changsha, China;2. College of Chemistry and Chemical Engineering, Hunan University of Science and Technology , Xiangtan, China zhou7381@sohu.com;4. State Key Laboratory for Powder Metallurgy , Central-South University , Changsha, China |
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| Abstract: | The influence of non-isothermal melt crystallization on thermal behavior and isothermal melt crystallization kinetics of poly-L-lactide (PLLA) were investigated by differential scanning calorimetry (DSC), polarizing micrograph (POM) and x-ray diffraction (XRD). Crystallization performed at lower cooling rates (2°C·min?1) is accompanied by a variation of the kinetics around 118°C. The glass transition temperature of PLLA decreases with increase of cooling rate, and the crystallinity at the end of crystallization increases with decreasing cooling rate. The size of PLLA spherulites increases with a decrease in the cooling rate, and PLLA becomes almost amorphous cooled at rapid rate (>10°C·min?1). PLLA exhibits an Avrami crystallization exponent n = 3.01±0.13 in isothermal crystallization in the range from 90°C to 140°C. According to Hoffman-Lauritzen theory, two crystallization regime are identified with a transition temperature occurring at 118°C, and the value of Kg(II)/Kg(III) is 2.17 [Kg(II) = 6.025 × 105K2, Kg(III) = 1.307 × 106 K2]. |
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| Keywords: | Crystallization behavior Isothermal crystallization Non-isothermal melt crystallization Poly-L-Lactide |
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