Studying the Structure and Properties of Epoxy Composites Modified by Original and Functionalized with Hexamethylenediamine by Electrochemically Synthesized Graphene Oxide.

In this study, we used multilayer graphene oxide (GO) obtained by anodic oxidation of graphite powder in 83% sulfuric acid. The modification of GO was carried out by its interaction with hexamethylenediamine (HMDA) according to the mechanism of nucleophilic substitution between the amino group of HMDA (HMDA) and the epoxy groups of GO, accompanied by partial reduction of multilayer GO and an increase in the deformation of the carbon layers. The structure and properties of modified HMDA-GO were characterized using research methods such as scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FTIR), X-ray diffraction spectroscopy and Raman spectroscopy. The conducted studies show the effectiveness of using HMDA-OG for modifying epoxy composites. Functionalizing treatment of GO particles helps reduce the free surface energy at the polymer-nanofiller interface and increase adhesion, which leads to the improvement in physical and mechanical characteristics of the composite material. The results demonstrate an increase in the strength and elastic modulus in bending by 48% and 102%, respectively, an increase in the impact strength by 122%, and an increase in the strength and elastic modulus in tension by 82% and 47%, respectively, as compared to the pristine epoxy composite which did not contain GO-HMDA. It has been found that the addition of GO-HMDA into the epoxy composition initiates the polymerization process due to the participation of reactive amino groups in the polymerization reaction, and also provides an increase in the thermal stability of epoxy nanocomposites.

Electrodeposition and Properties of Composite Ni Coatings Modified with Multilayer Graphene Oxide.

Within the framework of this study, Ni-based composite electrochemical coatings (CECs) modified with multilayer graphene oxide (GO) processed using microwave radiation have been deposited. The process of these coatings' electrodeposition in the potentiodynamic mode has been studied. The structure of Ni-GO and Ni-GO (MW) CECs has been studied using X-ray phase analysis (XPA) and scanning electron microscopy (SEM).It has been shown that the addition of GO into a nickel deposit contributes to the formation of uniform fine-grained coatings. As a result, the microhardness of the Ni-GO (MW) CECs increases by 1.40 times compared to Ni without GO. The corrosion-electrochemical behavior of nickel CECs in 0.5 M H2SO4 solution was researched. It was established that the corrosion rate of the nickel-GO (MW) CEC in 3.5% NaCl decreases by about 1.70 times in contrast to unmodified nickel coatings. This effect is due to the absence of agglomeration of the graphene oxide in the volume of the nickel matrix and the impermeability of GO particles to the corrosive environment.

Electrodeposition and Corrosion Properties of Nickel-Graphene Oxide Composite Coatings.

Nickel-based composite electrochemical coatings (CEC) modified with multilayer graphene oxide (GO) were obtained from a sulfate-chloride electrolyte in the reverse electrolysis mode. The microstructure of these CECs was investigated by X-ray phase analysis and scanning electron microscopy. The corrosion-electrochemical behavior of nickel-GO composite coatings in a 0.5 M solution of H2SO4was studied. Tests in a 3.5% NaCl solution showed that the inclusion of GO particles into the composition of electrolytic nickel deposits makes their corrosion rate 1.40-1.50 times less.

Epoxy Nanocomposites Reinforced with Functionalized Carbon Nanotubes.

In this article, amino functionalized multiwalled carbon nanotubes (MWCNTs) were prepared by chemical modification of the surface of a MWCNTs using γ-aminopropyltriethoxysilane (APTES) and dispersed into the epoxy composition. The modifying agent (APTES) was directly deposited on the MWCNTs surfaces. For the functionalization of MWCNTs, was used not the APTES concentrate, as it had been described in previous works, but its freshly prepared aqueous solution. Properties of APTES-treated MWCNTs were characterized by transmission electron microscope (TEM), Raman spectroscopy and FT-IR. The results showed that the functionalization and chemical compatibility of APTES-treated MWCNTs with epoxy composition provides their best dispersion in the epoxy composition, had important influence on curing behavior, structure and physicochemical properties of the epoxy composites plasticized with trichloroethyl phosphate. The results showed that the functionalization and chemical compatibility of APTES-treated MWCNTs with epoxy composition provides increased of physicomechanical properties of epoxy composites: bending stress increases by 194% and bending modulus increases by 137%, the tensile strength increases by 108% and the tensile elastic modulus increases by 52%, impact strength increases by 300%, in comparison with plasticized epoxy composite that does not contain MWCNTs.