The Kinetics of Melting Crystallization of Poly-L-Lactide
The Kinetics of Melting Crystallization of Poly-L-Lactide
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DOI：
10.1080/03602550701279994
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发表时间：
2007-08
影响因子：
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通讯作者：
Zhou Zhi-hua;Ruan Jian-ming;Z. Zhong-cheng;Zou Jian-peng
中科院分区：
文献类型：
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作者：
Zhou Zhi-hua;Ruan Jian-ming;Z. Zhong-cheng;Zou Jian-peng
采用差示扫描量热法（DSC）、偏光显微镜（POM）和X射线衍射（XRD）研究了非等温熔融结晶对聚L-乳酸（PLLA）热行为和等温熔融结晶动力学的影响。在较低的冷却速率（2°C·min-1）下进行的结晶伴随着118°C附近的动力学变化。PLLA的玻璃化转变温度随降温速率的增加而降低，结晶终了时的结晶度随降温速率的降低而增加。PLLA球晶的尺寸随着冷却速率的降低而增加，并且PLLA在快速冷却（>10°C·min-1）时几乎变成无定形。PLLA在90°C至140°C的等温结晶中表现出Avrami结晶指数n = 3.01±0.13。根据Hoffman-Lauritzen理论，确定了两个结晶区域，转变温度为118°C，Kg（II）/Kg（III）值为2.17 [Kg（II）= 6.025 × 105 K ~ 2，Kg（III）= 1.307 × 106 K ~ 2]。
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].