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首页> 外文期刊>Journal of Applied Polymer Science >Crystallization kinetics of poly (L-lactic acid)/montmorillonite nanocomposites under isothermal crystallization condition
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Crystallization kinetics of poly (L-lactic acid)/montmorillonite nanocomposites under isothermal crystallization condition

机译：等温结晶条件下聚（L-乳酸）/蒙脱土纳米复合材料的结晶动力学

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摘要

Poly(L-lactic acid)/o-MMT nanocomposites, incorporating various amounts of organically modified montmorillonite (o-MMT; 0-10 wt %), were prepared by solution intercalation. The montmorillonite (MMT) was organically modified with dilauryl dimethyl ammonium bromide (DDAB) by ion exchange. Transmission electron microscopy (TEM) and X-ray diffraction (XRD) reveal that the o-MMT was exfoliated in a poly(L-lactic acid), (PLLA) matrix. A series of the test specimens were prepared and subjected to isothermal crystallization at various temperatures (T _1-T _5). The DSC plots revealed that the PLLA/o-MMT nanocomposites that were prepared under nonisothermal conditions exhibited an obvious crystallization peak and recrystallization, but neat PLLA exhibited neither. The PLLA/o-MMT nanocomposites (2-10 wt %) yielded two endothermic peaks only under isothermal conditions at low temperature (T _1), and the intensity of Tm _2 (the higher melting point) was proportional to the o-MMT content (at around 171°C). The melting point of the test samples increased with the isothermal crystallization temperature. In the Avrami equation, the constant of the crystallization rate (k) was inversely proportional to the isothermal crystallization temperature and increased with the o-MMT content, especially at low temperature (T _1). The Avrami exponent (n) of the PLLA/o-MMT nanocomposites (4-10 wt %) was 2.61-3.56 higher than that of neat PLLA, 2.10-2.56, revealing that crystallization occurred in three dimensions.
机译：通过溶液插层制备掺入了各种量的有机改性蒙脱石（o-MMT; 0-10wt％）的聚（L-乳酸）/ o-MMT纳米复合材料。蒙脱石（MMT）通过二月桂基二甲基溴化铵（DDAB）通过离子交换有机改性。透射电子显微镜（TEM）和X射线衍射（XRD）显示，o-MMT在聚（L-乳酸）（PLLA）基质中脱落。制备了一系列试样，并在不同温度（T _1 -T _5）下进行了等温结晶。 DSC图显示，在非等温条件下制备的PLLA / o-MMT纳米复合材料表现出明显的结晶峰和重结晶，而纯PLLA则没有。 PLLA / o-MMT纳米复合材料（2-10 wt％）仅在低温（T _1）等温条件下产生两个吸热峰，并且Tm _2的强度（较高的熔点）与o-MMT含量成比例（在171°C左右）。测试样品的熔点随着等温结晶温度的升高而增加。在Avrami方程中，结晶速率的常数（k）与等温结晶温度成反比，并且随o-MMT含量的增加而增加，特别是在低温（T _1）时。 PLLA / o-MMT纳米复合材料（4-10 wt％）的Avrami指数（n）比纯PLLA的2.10-2.56高2.61-3.56，这表明结晶发生在三个维度上。

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