Synthesis of epoxy composites with high carbon nanotube loading and effects of tubular and wavy morphology on composite strength and modulus

Single-walled carbon nanotube (SWCNT)/epoxy composites with a high nanotube loading up to ∼39.1 wt% are fabricated by combining the mixed-curing-agent assisted layer-by-layer method and the hot press process. This combined method is an efficient and effective approach for making composite sheets in practical applications since the hot press process makes it possible and easy to readily prepare thick and large composites. The tensile and dynamic properties are greatly improved by the incorporation of SWCNTs. At ∼39.1 wt% SWCNTs, compared with those of the neat epoxy, the tensile strength and Young’s modulus are increased by 183% and 408%, respectively. The storage modulus is also significantly increased by 406% at room temperature due to this high loading of SWCNTs. Moreover, the loss factor in the temperature range −100–200 °C shows dramatic improvements by the introduction of high loading SWCNTs. Finally, analytical modeling is proposed to predict the strength and modulus of the CNT/epoxy composites by considering the effects of the tubular and wavy morphology of the CNTs. Both composite strength and composite modulus are found to decrease substantially with increasing waviness ratio. The predicted results show reasonable agreement with experimental data.