Improving mechanical properties of high volume fraction aligned multi-walled carbon nanotube/epoxy composites by stretching and pressing

Aligned multi-walled carbon nanotube (CNT) sheets produced from aligned CNT arrays were used to develop high volume fraction CNT/epoxy composites. Stretching and pressing techniques were applied during CNT sheet processing to straighten the wavy CNTs and to enhance the dense packing of CNTs in the sheets. Raman spectra measurements showed better CNT alignment in the CNT sheets and the composites after stretching and pressing. Aligned CNT/epoxy composites with CNT volume fraction up to 63.4% were developed using hot-melt prepreg processing with a vacuum-assisted system. Stretching and pressing of the CNT sheets enhanced the mechanical properties of high volume fraction CNT/epoxy composites considerably. Stretching and pressing increased tensile strength of the composites by 32% and elastic modulus of the composites by 27%. Applying stretching and pressing is effective for production of superior CNT sheets with high alignment and dense packing of CNTs, thereby supporting the development of high-performance CNT composites.