Investigation of the mechanical, thermal, and anticorrosion properties of epoxy nanocomposite coatings: Effect of synthetic hardener and nanoporous graphene

Abstract

In the present study, epoxy samples containing nanoporous graphene (NPG) were synthesized and analyzed in terms of mechanical, morphological, thermal, adhesion, and anticorrosion properties. To this end, the employed curing agents (hardeners) were synthesized and NPG content was varied from 0 to 1 wt %. By using a hardener with aliphatic side chains, the toughness of the nanocomposite was improved without a decrease in the modulus. Adding 1 wt % NPG increased the modulus of the nanocomposite by about 30%. The dynamic mechanical results showed an increment in the glass transition of the samples containing 1 wt % NPG. Field emission scanning electron microscopy images were used to observe the fracture surface of the nanocomposites. The thermogravimetric analysis analysis also confirmed that using synthetic hardener and NPG as the nanofiller enhanced the thermal resistance of the samples. The images of the protected metal panel surfaces and their coatings were used to study adhesion and anticorrosion properties. These results indicated that the hardener synthesized in this work along with NPG improved the mechanical, thermal, adhesion, and anticorrosion properties of the epoxy nanocomposites effectively. The specific characteristic of the synthetic hardener was its chemical structure including both aliphatic and cyclic polyamines as the side groups. V C 2018 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018, 135, 46201.

Reinforcing effect of amine‐functionalized and carboxylated porous graphene on toughness, thermal stability, and electrical conductivity of epoxy‐based nanocomposites

“…In an effort to profoundly investigate the influence of the modified NPGs on the mechanical properties of the epoxy nanocomposites, impact analysis was accomplished. Figure demonstrates that introducing NPG decreases the impact strength with a gentle slope, and, as aforementioned, the addition of NPG causes further brittleness and stiffness in the structure of polymer, thereby reducing the impact strength . On the contrary, functionalized NPGs offered a completely inverse trend.…”

“…As shown in Figure , the addition of low amounts of NPG led to noticeable increments in modulus and tensile strength of the nanocomposites. This is attributed to the restricted segmental mobility of polymer chains in the presence of nanoparticles, resulting in the stiffness enhancement of the epoxy network . However, the calculation of area under the curves confirms a reduction in toughness leading to a more brittle behavior compared to the neat resin.…”

“…Figure represents the tan delta (tanδ) plot over a wide temperature range for the purpose of excessively investigating the effect of functionalization on the crosslinking network of the polymer together with a better understanding of toughness improvement sources. Employing nanomaterials into the epoxy nanocomposites enhances the T g , determined by the peaks of tan delta curves, mainly because of the mobility limitations induced to the polymer molecules . By comparing the peaks of tan delta curves, a scarce drop in T g could be observed when shifting from the NPG‐reinforced nanocomposites to the functionalized‐NPG loaded ones at a content of 2.0 wt %.…”

“…Carbon‐based nanomaterials, including carbon nanotubes (CNTs), carbon nanohorns, and carbon nanocones/disks; and graphene and its derivations, such as graphene nanoplatelets (GNPs), porous graphene (NPG's), and graphene oxide (GO), are highly consumed as a means to modify the mechanical properties and toughness of epoxy‐based nanocomposites . Among nanocarbon materials, graphene, an atomic‐scale material with two‐dimensional (2D) honeycomb lattice and high‐specific surface area, has gained greater heed due to its magnificent properties.…”

“…Furthermore, it is worth mentioning that graphene is capable of fostering thermal and electrical properties of epoxy resin nanocomposites without hampering its stiffness (limiting its mechanical properties) . In our previous study, a synthetized porous graphene was added to epoxy matrices cured with four various hardeners in varying contents from 0 to 1 wt %. It was concluded that all the epoxy nanocomposites experienced a slight increment in modulus and glass‐transition temperature ( T g ), while the impact strength of the all specimens dropped, indicating a reduction in toughness as a result of adding NPG into epoxy resins.…”