Isothermal crystallization kinetics and melting behavior of multiwalled carbon nanotubes/polyamide-6 composites
Isothermal crystallization kinetics and melting behavior of multiwalled carbon nanotubes/polyamide-6 composites
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DOI：
10.1002/app.24606
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发表时间：
2007-09-15
影响因子：
3
通讯作者：
Uu, Fu
中科院分区：
文献类型：
--
作者：
Li, Juan;Fang, Zhengping;Uu, Fu
原始和功能化多壁碳纳米管（MWNT）用于通过熔融共混制造聚酰胺6（PA6）复合材料。通过将 1,6-六亚甲基二胺 (HMD) 接枝到原始 MWNT 上以提高其与 PA6 基质的相容性，获得功能化 MWNT。通过差示扫描量热法（DSC）和X射线衍射（XRD）研究了MWNT对PA6等温结晶和熔融行为的影响。 Avrami 和 Lauritzen-Hoffmann 方程用于描述等温结晶动力学。纯 PA6、原始 MWNT/PA6 和功能化 MWNT/PA6 复合材料样品的 Avrami 指数值分别约为 4.0、1.7 和 2.3。复合材料的活化能通过阿伦尼乌斯法测定，原始 MWNTs/PA6 的活化能为 -320.52 KJ/mol，功能化 MWNTs/PA6 的活化能为 -293.83 KJ/mol，低于纯 PA6 的活化能 (-284.71 KJ/mol)。以下熔化行为表明，所有等温结晶样品在较低结晶温度下表现出三重熔化吸热，在较高结晶温度下表现出双重熔化吸热。多次熔融吸热主要是由于PA6在加热过程中发生再结晶造成的。复合材料的平衡熔化温度低于纯 PA6。此外，还使用偏光显微镜（PLM）和小角度光扫描（SALS）来研究球晶形态。结果表明，MWNT 降低了 PA6 的球晶半径。对于原始 MWNT，这种减少更为显着。 (C) 2007 年 Wiley 期刊公司。
Pristine and functionalized multiwalled carbon nanotubes (MWNTs) were used to fabricate polyamide 6 (PA6) composites through melt blending. The functionalized MWNTs were obtained by grafting 1,6-hexamethylenediamine (HMD) onto the pristine MWNTs to improve their compatibility with PA6 matrix. The effect of MWNTs on the isothermal crystallization and melting behavior of PA6 was investigated by differential scanning calorimetry (DSC) and X-ray diffraction (XRD). The Avrami and Lauritzen-Hoffmann equations are used to describe the isothermal crystallization kinetics. The values of the Avrami exponent found for neat PA6, the pristine MWNTs/PA6 and functionalized MWNTs/PA6 composite samples are about 4.0, 1.7, and 2.3, respectively. The activation energies are determined by the Arrhenius method, which is lower for the composites, -320.52 KJ/mol for pristine MWNTs/PA6 and -293.83 KJ/ mol for functionalized MWNTs/PA6, than that for the neat PA6 (-284.71 KJ/mol). The following melting behavior reveals that all the isothermally crystallized samples exhibit triple melting endotherms at lower crystallization temperature and double melting endotherms at higher crystallization temperature. The multiple melting endotherms are mainly caused by the recrystallization of PA6 during heating. The resulting equilibrium melting temperature is lower for the composites than for neat PA6. In addition, polarizing microscopy (PLM) and small angle light scanning (SALS) were used to study the spherulite morphology. The results show that the MWNTs reduce the spherulite radius of PA6. This reduction is more significant for pristine MWNTs. (C) 2007 Wiley Periodicals, Inc.