New Techniques Stretch Carbon Nanotubes, Make Stronger Composites

来自北卡罗来纳州立大学的研究人员开发了用于拉伸碳纳米管（CNT）的新技术，并使用它们来创建碳复合材料，这些碳复合材料可以用作从飞机到自行车的所有物质中更强大，更轻的材料。

通过将CNT材料纳入用于成品的复合材料之前，将其拉伸，研究人员将CNT拉直材料中的CNT，从而显着提高了其拉伸强度 - 并增强了复合材料的刚度及其电导和导热率。

目前，最先进的碳纤维复合材料用于制造飞机和其他产品，这些产品是可取的，强大，轻巧的材料。例如，较轻的飞机更加燃油效率。但是，研究人员长期以来一直认为，如果可以用CNT制成这些复合材料，则可能同样强，但要轻10倍。或者它们的重量可能相同，但强大10倍。

创建强大的CNT复合需要四个功能。首先，它需要长的CNT，在承载负载方面更有效。其次，CNT需要在行中对齐。第三，材料中的CNT由聚合物或树脂组合在一起，并且您需要在成品复合材料中具有高比例的CNT与聚合物。第四，您需要CNT尽可能笔直，以使材料的重量均匀。

For decades, researchers have been unable to achieve these goals. But now a research team, led by Dr. Yuntian Zhu, a professor of materials science and engineering at NC State, has developed a solution.

朱说：“新技术始于CNT阵列，这看起来像是从平坦的基材上长大的CNT森林。”由于这些CNT的长宽比很高，因此它们又长又瘦 - 不刚性。这意味着CNT在阵列中相互倾斜。朱说：“通过在数组的一端抓住CNT，我们可以将它们拉到它们的侧面 - 以及阵列中的所有其他CNT沿同一方向倾倒。”这导致CNT具有良好的对准。

然后，这些对齐的CNT被缠绕在旋转的线轴上，并用聚合物溶液喷洒以将CNT结合在一起。这会产生带有丝带的复合材料，该材料具有很高的CNT量，该材料又可以用来制造CNT复合结构，以用于飞机和自行车等成品。但这并不能解决拉直CNT的必要性。

To straighten the CNTs, Zhu and his team stretched the CNTs as the nanotubes are being pulled onto the rotating spool. This process improves the tensile strength of the CNT composite “ribbon” by approximately 90 percent (to an average of 3.5 gigapascals) and stiffness by more than 100 percent. By straightening the CNTs, the researchers were also able to almost triple the CNT composite’s thermal conductivity, to 40 watts per meter per kelvin. Electrical conductivity was increased by 50 percent to 1,230 siemens per meter.

伸展CNT以拉直它们的论文：“超级薄膜的Ultrastrong，僵硬和多功能膜，由超级对齐的碳纳米管组装，”在线发表在《期刊》上材料研究信. The research was supported, in part, by the Air Force Office of Scientific Research and the North Carolina Space Grant.

Researchers involved with the work came from NC State, Suzhou Institute of Nano-Tech and Nano-Bionics, Donghua University, Marshall Space Flight Center, Oak Ridge National Laboratory, and Los Alamos National Laboratory.

- 船员 -

给编辑的注释：研究摘要如下。

“超级僵硬且多功能膜，由超级对齐的碳纳米管组装”

作者：Xin Wang，Philip D. Bradford，Fuh-Gwo Yuan和Yuntian Zhu，北卡罗来纳州立大学；Zhenzhong Yong，Qingwen li，苏州纳米技术学院和纳米生物学学院；刘刘，东杜大学；丹尼斯·塔克（Dennis S. Tucker），马歇尔太空飞行中心；Wei Cai，Hsin Wang，Oak Ridge国家实验室

出版：在线，2012年10月11日，材料研究信

抽象的：开发一种新型路线ultrastro做准备ng, stiff and thermally and electrically conductive carbon nanotube (CNT) composite films. The free-standing unidirectional films, with controlled thicknesses, are prepared by incorporating superaligned CNTs into polymer matrix via stretch-winding. The obtained CNT composite films exhibit unprecedented multifunctionalities of any known engineering composites, including highest values for tensile strength (3.8 GPa), Young’s modulus (293 GPa), electrical conductivity (1200 S cm-1) and thermal conductivity (40 W m-1 K-1). Such CNT/polymer film can also withstand severe bending and maintain the high electrical conductivity after being bent for 1000 cycles. These superior properties are primarily derived from the long CNT length, high volume fraction, good CNT alignment and reduced waviness of the CNTs. The combination of high strength and excellent thermal and electrical conductivities makes it promising to improve and enable new aerospace technologies and adventures.