Polymorphism of nylon‐6 in multiwalled carbon nanotubes/nylon‐6 composites
Polymorphism of nylon‐6 in multiwalled carbon nanotubes/nylon‐6 composites
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DOI：
10.1002/polb.20808
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发表时间：
2006-05
期刊：
影响因子：
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通讯作者：
Juan Li;Zhengping Fang;L. Tong;A. Gu;Fu Liu
中科院分区：
文献类型：
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作者：
Juan Li;Zhengping Fang;L. Tong;A. Gu;Fu Liu
采用差示扫描量热法和X射线衍射法研究了氨基功能化多壁碳纳米管（MWNTs）对尼龙6结晶行为的影响。结果表明，在尼龙-6及其复合材料中存在多晶型，这取决于MWNTs的浓度和冷却速率。更多的MWNTs和从熔体缓慢冷却有利于α晶型的形成。随着冷却速率的增加，纯尼龙6的结晶度降低，复合材料的结晶度先降低后升高。此外，在高冷却速率下，复合材料的结晶度高于纯尼龙-6，与在低冷却速率下观察到的相反。多壁碳纳米管诱导的异相成核和聚合物链的受限流动性被认为是主要因素。此外，MWNTs的加入增加了α晶型的结晶速率，但MWNTs的氨基官能化削弱了这种作用。讨论了热处理对MWNTs/尼龙6复合材料结晶结构的影响。与尼龙6相比，MWNTs/尼龙6复合材料在较低的温度下发生了γ-α相变。复合材料在160 °C退火时的退火峰高于纯尼龙6，其中氨基官能化MWNTs/尼龙6复合材料的退火峰最高。这一现象与不同碳纳米管在受限空间中不同的成核和再结晶行为密切相关。© 2006 Wiley Periodicals，Inc.聚合物科学杂志B部分：聚合物物理44：1499-1512，2006
The effects of pristine and amino-functionalized multiwalled carbon nanotubes (MWNTs) on the crystallization behaviors of nylon-6 were investigated by differential scanning calorimetry and X-ray diffraction. The results indicate the presence of polymorphism in nylon-6 and its composites, which is dependent on the MWNTs concentration and the cooling rate. More MWNTs and slow cooling from the melt favors the formation of α crystalline form. With the increase in cooling rates, the crystallinity of neat nylon-6 decreases, and that of the composites decreases initially but increases afterward. Moreover, the degree of crystallinity of the composites is higher than neat nylon-6 under high cooling rates, counter to what is observed under low cooling rates. The heterogeneous nucleation induced by MWNTs and the restricted mobility of polymer chains are considered as the main factors. Furthermore, addition of MWNTs increases the crystallization rate of α crystalline form but amino-functionalization of MWNTs weakens this effect. The influence of thermal treatment on the crystalline structure of MWNTs/nylon-6 composites is also discussed. A γ–α phase transition takes place at lower temperature for MWNTs/nylon-6 composites than for nylon-6. The annealing peaks of the composites annealed at 160 °C are higher than that of neat nylon-6, and the highest annealing peak is obtained for amino-functionalized MWNTs/nylon-6 composites. This phenomenon is closely related to the different nucleation and recrystallization behaviors produced by various MWNTs in confined space. © 2006 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 44: 1499–1512, 2006