School of Mechanical & Aerospace Engineering, Nanyang Technological University, 50 Nanyang Avenue, Singapore 639798, Singapore.
Small. 2010 Jan;6(1):132-7. doi: 10.1002/smll.200900954.
Vertically aligned carbon-nanotube arrays are synthesized by chemical vapor deposition. Carbon-nanotube fibers are directly spun from the obtained nanotube arrays and then tested mechanically. A strong correlation between the array morphologies and the mechanical properties of the fibers is observed: well-aligned arrays yield fibers with much higher performance, while wavy and entangled arrays give poor fiber properties. More importantly, such array morphologies could be controlled by introducing hydrogen or oxygen during the nanotube synthesis. By simply switching the growth condition from 150 ppm oxygen addition to 2% hydrogen addition, the nanotube array changes from the wavy morphology to the well-aligned morphology, and correspondingly the tensile strength of the resultant fibers could be increased by 4.5 times, from 0.29 GPa for the fibers spun from the oxygen-assistance-grown nanotube arrays to 1.3 GPa for the fibers spun from the hydrogen-assistance-grown nanotube arrays. The detailed effects of hydrogen and oxygen on the nanotube growth, especially on the growth rate and the array spinnability, are extensively studied. The formation mechanism of the different morphologies of the nanotube arrays and the failure mechanism of the nanotube fibers are also discussed in detail.
垂直排列的碳纳米管阵列是通过化学气相沉积合成的。碳纳米管纤维直接从得到的纳米管阵列中纺出，然后进行力学测试。观察到阵列形态和纤维力学性能之间存在很强的相关性：排列良好的阵列产生的纤维性能更高，而波浪形和缠结的阵列则产生较差的纤维性能。更重要的是，通过在纳米管合成过程中引入氢或氧，可以控制这种阵列形态。通过简单地将生长条件从添加 150ppm 氧气切换为添加 2%氢气，纳米管阵列从波浪形态变为排列良好的形态，相应地，从氧辅助生长的纳米管阵列纺出的纤维的拉伸强度可以增加 4.5 倍，从 0.29GPa 增加到 1.3GPa从氢辅助生长的纳米管阵列纺出的纤维。详细研究了氢和氧对纳米管生长的影响，特别是对生长速度和阵列可纺性的影响。还详细讨论了纳米管阵列不同形态的形成机制和纳米管纤维的失效机制。
