Abstract
Horizontally aligned multi-walled carbon nanotube (CNT) sheets were produced from vertically aligned CNT arrays using drawing and winding techniques. Composites based on epoxy resin and an aligned 100-ply CNT sheet have been developed using hot-melt prepreg processing. However, wavy and poor-packed CNTs in the sheets have limited reinforcement efficiency of the CNTs in the composites. In this study, a new simple stretch-drawing method was used to modify the structures of the aligned CNT sheets for improving the composite properties. The stretch-drawing of the CNT sheets enhanced the composite properties considerably. The improved properties of the composites originated from straightening of the wavy CNTs and increasing the CNT dense packing in the composites. With a 3% stretch ratio, the aligned CNT/epoxy composites achieved their best mechanical properties in this study. The 3% stretched composites exhibit increased tensile strength by 113% and enhanced elastic modulus by 34% compared to non-stretched ones. Results show that the simple stretch-drawing is effective to produce highly aligned CNT sheets for the development of high-performance CNT composites. Compared to our previous stretching method, the stretch-drawing method in this study is more effective in improving the mechanical properties of aligned CNT/epoxy composites.
Highlights
Carbon nanotubes (CNTs) have been regarded as the reinforcing agents for polymer composites because of their high aspect ratio, high surface area available for stress transfer, and excellent mechanical properties [1]
The G-band intensity ratio of the 3% stretched composite exhibited the highest value among all the composites, thereby achieving the best mechanical properties of the aligned CNT/epoxy composites in this study
Raman spectra measurements showed a higher alignment of CNTs in the sheets and their composites after the stretch-drawing
Summary
Carbon nanotubes (CNTs) have been regarded as the reinforcing agents for polymer composites because of their high aspect ratio, high surface area available for stress transfer, and excellent mechanical properties [1]. Most CNT-reinforced polymer composites have been composed by unorganized CNTs dispersed in polymer matrices [2]. Those composites could not fully take advantage of the excellent properties of CNTs because of low volume fraction and easy agglomeration in the dispersion of CNTs. recent studies have focused on developing vertically aligned CNT arrays [3] and horizontally aligned CNT sheets [4]. The handling of the CNT sheets without resin for the stretching is generally difficult because of static electricity [5] To overcome this difficulty, a simple stretch-drawing method was proposed in this study to straighten the wavy CNTs and to reduce the poor-packed CNTs for improving their composite properties. Effect of the stretchdrawing on the mechanical properties of aligned CNT/epoxy composites was examined
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