Carbon nanotube-reinforced epoxy composites in seawater: effect of amino-functionalization and post-curing process

Due to their extraordinary properties, functionalized carbon nanotubes (CNTs) have been added to epoxy matrices. In the marine industry, CNT/epoxy composite is applied in current turbines to obtain energy. For this, it is fundamental to understand the nanocomposites’ seawater absorption process. Therefore, this work aims to study how amino-functionalized CNTs and epoxy’s post-cure reaction influences the nanocomposites’ seawater absorption. The nanocomposites were prepared with ethylenediamine functionalized CNTs (0.25 wt%). Part of the samples was exposed to a post-cure treatment and artificial seawater for 504 days, accompanied by mass measurement. Then, the percentage of water absorbed throughout the period was obtained, and the post-cured samples absorbed the highest water amount, as well as showed the highest values of the glass transition temperature. The action of water as a plasticizer or pseudo-curing agent was observed by luminescence spectroscopy. Additionally, the three-point bending test showed that the highest modulus of elasticity was presented by the post-cured nanocomposites exposed to water, which also presented fracture with little plastic deformation, while the equivalent sample without the presence of CNT showed significant plastic deformation. Thus, since the marine industry requires materials with high bending forces, the amino-CNT/epoxy nanocomposites are suitable for this application.