Rheological behavior of multiwalled carbon nanotube/polycarbonate composites
Rheological behavior of multiwalled carbon nanotube/polycarbonate composites
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DOI：
10.1016/s0032-3861(02)00612-2
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发表时间：
2002-05-01
期刊：
影响因子：
4.6
通讯作者：
Paul, DR
中科院分区：
文献类型：
--
作者：
Pötschke, P;Fornes, TD;Paul, DR
用振荡流变仪在260°c下研究了含有0.5 ~ 15wt %碳纳米管的聚碳酸酯压缩成型混合物的流变行为。纳米管的直径在10到15纳米之间，长度在1到10微米之间。复合材料是用双螺杆挤出机稀释含有15wt %纳米管的母粒得到的。与添加纳米管相关的粘度增加远远高于具有较大直径的碳纳米纤维和炭黑复合材料的粘度变化，这可以通过纳米管的高长宽比来解释。黏度的增加伴随着弹性熔体性能的增加，以储存模量G′表示，其远高于损失模量G′′的增加。高于2 wt%纳米管的黏度曲线比含有较低纳米管负载的样品表现出更大的频率下降。含有超过2 wt%纳米管的复合材料在较低频率下表现出非牛顿行为。在低频率下，观察到纳米管的粘度-组成曲线在约2 wt%时阶跃增加。这一步骤的变化可被视为神学的门槛。最终，流变性阈值与电导率渗透阈值一致，该阈值在1 ~ 2 wt%之间。(C) 2002 Elsevier Science Ltd.版权所有。
The theological behavior of compression molded mixtures of polycarbonate containing between 0.5 and 15 wt% carbon nanotubes was investigated using oscillatory rheometry at 260 degreesC. The nanotubes have diameters between 10 and 15 nm and lengths ranging from I to 10 mum. The composites were obtained by diluting a masterbatch containing 15 wt% nanotubes using a twin-screw extruder. The increase in viscosity associated with the addition of nanotubes is much higher than viscosity changes reported for carbon nanofibers having larger diameters and for carbon black composites this can be explained by the higher aspect ratio of the nanotubes. The viscosity increase is accompanied by an increase in the elastic melt properties, represented by the storage modulus G', which is much higher than the increase in the loss modulus G". The viscosity curves above 2 wt% nanotubes exhibit a larger decrease with frequency than samples containing lower nanotube loadings. Composites containing more than 2 wt% nanotubes exhibit non-Newtonian behavior at lower frequencies. A step increase at approximately 2 wt% nanotubes was observed in the viscosity-composition curves at low frequencies. This step change may be regarded as a theological threshold. Ultimately, the rheological threshold coincides with the electrical conductivity percolation threshold which was found to be between I and 2 wt%, nanotubes. (C) 2002 Elsevier Science Ltd. All rights reserved.