Synthesis of vertically aligned Carbon nano tube and its application for Polymer matrix composite

碳纳米管具有高导电性、高杨氏模量和高抗拉强度等优良性能，是聚合物基复合材料的填料。目前，碳纳米管填料多采用气相沉积法制备，质量普遍不佳。因此，本研究的目的是阐明碳纳米管质量对聚合物基碳纳米管复合材料性能的影响，并开发具有优异性能的聚合物基碳纳米管复合材料。首先，制备了约600 μm长的碳纳米管作为复合材料的填料。然后将碳纳米管分别在1500、1800和2000℃退火，以提高碳纳米管的质量。其次，用未接收和退火的CNTs形成CNT/聚碳酸酯复合材料。然后对复合材料进行了电阻率和抗拉强度测试。结果表明，含有高质量碳纳米管的复合材料的电阻率较低，仅为含有相同碳纳米管的复合材料的十分之一。表面电阻率范围为102 ~ 103 Ω/sq，电阻率为抗静电材料的可行水平。与此同时，高质量碳纳米管的复合材料的杨氏模量和抗拉强度低于普通碳纳米管的复合材料。这是因为高质量碳纳米管的表面是惰性的，与聚合物的附着力较弱。我发现在退火碳纳米管试样的断口中拔出了许多碳纳米管。高质量的碳纳米管并不总是有利于聚合物基碳纳米管复合材料的性能。应用表面改性技术改善聚合物基碳纳米管复合材料的力学性能具有重要意义。

CNT has excellent properties such as high electric conductivity and high Young’s modulus and high tensile strength, hence they are used as filler for polymer matrix composite. Now, CNT as filler are made by CVD method and the quality of them are generally not good. So the purpose in this study is to clarify the effect of CNT quality on the properties of polymer based CNT composite and to develop polymer matrix CNT composite which have excellent properties.First, about 600 μm long CNT were prepared as filler for composites. Then the CNT were annealed at 1500, 1800 and 2000 degrees C to improve the quality. Second, CNT/Polycarbonate composite were formed with as received and annealed CNTs. Then resistivity and tensile strength test of the composite were measured. As a result, the composite with higher quality CNTs showed lower resistivity and one tenth resistivity of the composite with as received CNT. The range of surface resistivity is from 102 to 103 Ω/sq and the resistivity is workable level as antistatic materials. Meanwhile, the composite with high quality CNT showed lower Young’s modulus and tensile strength than the composite with as received CNT. That’s reason is the surface of high quality CNT is inert and attaches to polymer weakly. I found many CNTs pulled out in the fracture of the specimen with annealed CNT. High quality CNT is not always good for the properties of polymer matrix CNT composite. It is important to apply surface modification technique to improve the mechanical properties of polymer matrix CNT composites.