Abstract
Helical carbon nanotubes (HCNTs) were functionalized to fabricate HCNT/epoxy composites. Acid oxidation and a silane coupling agent, glycidoxypropyltrimethoxysilane (KH560), were used to modify the HCNTs. Remarkably, the flexural strength and the flexural strain were enhanced by 72.0% and 325.0%, respectively, compared to pure epoxy after adding a small amount of the KH560 modified HCNTs (K-HCNTs). Simultaneously, the tensile strength and Young’s modulus of K-HCNTs/epoxy composites were 51.3% and 270.9% higher than those of pure epoxy. It is found that the presence of silane molecules improved the dispersion of HCNTs in epoxy and the interfacial interaction. Moreover, it has been found that the mechanically interlocking effect from the helical shape of HCNTs also contributes to the improved mechanical properties of epoxy composites, compared to their straight multi-walled carbon nanotube (MWCNT) counterparts. This work provides a low-cost and efficient approach to strengthen and toughen epoxy composites.
Highlights
Epoxy resins have attracted great attention for wide applications in the aerospace and automobile industry, owing to their excellent mechanical properties, strong bonding strength and good thermal stabilities [1,2]
It has been found that the flexural strength and the flexural modulus of epoxy composites are increased by the addition of Triton-treated carbon nanotube (CNT), owing to the fact that the surfactant serves as an interfacial coupling agent and a dispersant [20]
These works suggested the incorporation of pristine Helical carbon nanotubes (HCNTs) into epoxy can endow the epoxy composites with better mechanical properties than compared with their straight counterparts
Summary
Epoxy resins have attracted great attention for wide applications in the aerospace and automobile industry, owing to their excellent mechanical properties, strong bonding strength and good thermal stabilities [1,2]. In addition to the chemical grafting modification, the nonionic surfactants are very effective to modify the CNTs for composites without deteriorating sp bonding of CNTs. It has been found that the flexural strength and the flexural modulus of epoxy composites are increased by the addition of Triton-treated CNTs, owing to the fact that the surfactant serves as an interfacial coupling agent and a dispersant [20]. The hardness, elastic modulus and tensile strength of HCNT/epoxy composites were significantly enhanced due to the good dispersion of HCNTs and the interlocking between the HCNTs and epoxy These works suggested the incorporation of pristine HCNTs into epoxy can endow the epoxy composites with better mechanical properties than compared with their straight counterparts. The contributions of straight CNTs and HCNTs on the mechanical properties of epoxy composites were compared to further reveal the strengthening and toughening mechanisms of HCNTs in epoxy
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