Long-term corrosion protection of styrene acrylic coatings enhanced by fluorine and nitrogen co-doped graphene oxide

Graphene materials are widely used as a physical barrier when applying anticorrosion polymer coatings due to their large surface area and layered structure. However, the electrical conductivity of intrinsic graphene can accelerate galvanic corrosion and shorten the protection period. In this work, fluorine and nitrogen co-doped graphene oxide (FNGO) was synthesized by a hydrothermal process and acted as an anticorrosion filler in waterborne styrene acrylic coatings. Styrene acrylic coatings with 0.4 wt% FNGO showed a corrosion current density that was two orders of magnitude lower than the other samples in the potential polarization test and the largest impedance modulus in the electrochemical impedance spectroscopy (EIS) results. The outstanding corrosion protection was attributed to the graphene acting as a physical barrier and the synergistic effect of the doped fluorine and nitrogen. In addition to the “labyrinth effect” of the graphene matrix, the nitrogen atoms inserted in the graphene plane and fluorine atoms grafted on the graphene simultaneously adjusted the electrical properties of graphene, prohibiting electron transport between it and the styrene acrylic resin matrix. This result indicates that doped graphene oxide has great potential to increase the corrosion resistance of waterborne coatings.

Degradation of Sol-Gel Acrylic Coatings Based on Si and Zr Investigated Using Electrochemical Impedance, Infrared and X-Ray Photoelectron Spectroscopies

This study aimed to synthesise and characterise two types of sol-gel acrylic coatings: one based on Si and the other based on Si and Zr. These coatings, which served as a barrier for corrosion protection of aluminium, were synthesised by sol-gel methodology using silicon precursors tetraethyl orthosilicate and organically modified silicon precursor 3-methacryloxypropyltrimethoxysilane, without and with the addition of zirconium(IV) n-propoxide chelated with methacrylic acid. The synthesis process was followed using real-time Fourier transform infrared spectroscopy, which confirmed the condensation reactions of Si–O–Si and Si–O–Zr networks, depending on the sol type. This was reflected in the composition of the coating as well, as shown by X-ray photoelectron spectroscopy. The coating topography, thickness and morphology were analysed using focused ion beam scanning electron microscopy. X-ray photoelectron spectroscopy was employed to follow the degradation of acrylic coatings upon immersion in sodium chloride solution. Corrosion properties, evaluated using electrochemical impedance spectroscopy in 0.1 M NaCl, confirmed high barrier protection of coated aluminium with acrylic coatings based on Si and even better for coating based on Si with Zr. The more durable corrosion protection of the latter was also confirmed by salt spray testing.

The Influence of Battery Acid on the Destruction of Acrylic Coatings of Car Bodies

Renovation coatings of car bodies undergo destruction under the influence of operational factors. Like ultraviolet radiation, erosion, and aggressive media (among others, battery acid). This article concerns the evaluation of the influence of battery acid on the destruction of acrylic coatings previously non-aged, as well as aged climatically for 2 years. Ageing of the coatings with battery acid contributed to a degradation increase of their chemical structure. It was supported by a considerable increase in the polar component of surface free energy (SFE) of the coatings. In the case of prior climate ageing, the increase in the polar component was even higher. Moreover, the coating’s ability to absorb battery acid increased, which induced blistering. The DSC method revealed that the action of battery acid caused more intense oxidation of coating material, and as a result, the brittleness increased, leading to chipping of the coating surface layers. This led to the increase in surface roughness, measured using an interferometric method. The coatings previously climatically aged for 2 years presented higher values of surface roughness parameters than the non-aged ones. The increase in the surface roughness contributed to a substantial decrease in the gloss of coatings. A sharp difference in colour escalating with the lengthening of the ageing period was also observed using the spectrophotometric method.

Research of the Influence of Silicate Fillers on Water Absorption and Microstructure of Styrene-Acrylic Dispersion Coatings

Permeability is important to ensure the protective properties of coatings based on styrene-acrylic dispersions. This indicator characterizes the complex of insulating properties of coatings, their ability to prevent the penetration of liquids, vapors and gases from the environment to the surface to be protected. It was studied the effect of aluminosilicate microspheres, which are characterized by the hydrophilic nature of the surface and highly dispersed silicate filler aerosil with a hydrophobised surface on the water absorption of styrene-acrylic coatings. Decreased of water absorption of styrene-acrylic coatings filled with aluminosilicate microspheres with the introduction of hydrophobised aerosil is linked to the fact that the fine aerosil with a high specific surface area provides the formation of a more densely packed structure. Thus, partially filling the interspherical space, which is formed by particles of microspheres with a diameter of 10-100 μm and reduces the surface defect of the styrene-acrylic coating. Localization on the surface of defective structures of particles of hydrophobised aerosil leads to a decrease in wetting of defective structures with water. Resulting deteriorating wetting the surface of the styrene-acrylic coating. Micrographs were taken to assess the nature of the distribution of aerosil on the surface of the styrene-acrylic coating. The analysis of the obtained micrographs confirms that the introduction of microspheres form large agglomerates, between which there are vacancies, which will negatively affect the technological and operational properties of the developed coatings. At the same time, the introduction of aerosil allows to obtain a more orderly structure, which allows to obtain a coating with lower internal stresses, increased aggregate stability and, as a consequence, with improved technological and operational properties.

A MODIFYING GO AND DOPING IT IN WATERBORNE ACRYLIC COATINGS TO ENHANCE THEIR MECHANICAL PERFORMANCE AND CORROSION PROTECTION

With the development of science and technology and the ever-increasing focus of the environmental protection, waterborne acrylic resin based coating has been commonly used in a wide range of applications due to its high flexibility and good UV resistance. Continuous attempts have been extensively carried out to improve its corrosion resistance and mechanical properties through doping of different nanomaterials. In this study, Functionalized Graphene Oxide (FGO) nanosheets covalently bonded to hydroxylated acrylic resin was introduced into the Hydroxyacrylic Acid Dispersion (HAD) matrix to enhance the performance. To study the effect of grafted hydroxylated acrylic resin on morphology and properties of GO nanosheets, the GO and FGO nanosheets have been systematically characterized with various testing methods, such as FTIR, field emission-scanning electron microscopy (FE-SEM), transmission electron microscope (TEM), Raman spectroscopy, X-ray diffraction (XRD) analysis, UV–vis analysis, and thermogravimetric analysis (TGA). The morphology, physical–mechanical, and anti-corrosion properties of the HAD coatings doped with GO and FGO nanosheets have been compared. The results confirmed that FGO’s dispersion behavior in the HAD matrix has been improved after modifification with the hydroxylated acrylic resin, and the interfacial bonds between the HAD-FGO nanosheets have been significantly enhanced.

Water-Borne ZnO/Acrylic Nanocoating: Fabrication, Characterization, and Properties

This work aims to explore how ZnO nanoparticles enhance the mechanical, photoaging, and self cleaning properties of water borne acrylic coating. Micro/nano ZnO particles (at 2 wt.% of total solid resin) were dispersed into the acrylic polymer matrices using ultrasonication to understand the effect of the size of the coating properties. The effect of ZnO particles on the properties of composite coatings (25 µm of thick) have been evaluated through various tests, such as abrasion measurement, ultraviolet/condensation (UV/CON) weathering aging, and methylene blue self cleaning. Experimental data indicated that the incorporation of ZnO particles enhanced both abrasion resistance and methylene blue removal efficiency of the water borne acrylic coatings, with nano ZnO particles being the best. However, the weathering degradation of nanocomposite coatings was more severe as compared to the coating with micro ZnO (at the same ZnO content).

Size effect of R-TiO\(_{2}\) (Micro- and Nano-) Particles on the Mechanical Property, Weathering Durability of Water-based Acrylic Coating

This work aims to clarify the difference between the influence of TiO\(_{2}\) particles at micrometer and nanometer sizes on the mechanical properties and weathering durability of water-based acrylic coatings. To prepare coatings, micro-R-TiO\(_{2}\) and nano R-TiO\(_{2}\) particles with 2 wt.% content were dispersed in the emulsion acrylic polymer by ultrasonic vibration. The coatings without TiO\(_{2}\) particles, with 2 wt.% micro R-TiO\(_{2}\) and with 2 wt.% nano R-TiO\(_{2}\) were tested for abrasion resistance, weathering aging in UV/CON accelerated weathering chamber. Weathering aging was assessed by IR quantitative analysis, the weight loss of the coating. The obtained results showed that the micro R-TiO\(_{2}\) with the 2 wt.% content enhanced simultaneously the abrasion resistance and weathering durability of water-based acrylic coatings but not as effectively as nano R-TiO\(_{2}\). Incorporation of 2 wt.% micro-R-TiO\(_{2}\) increased slightly the abrasion resistance of coating from 78.4 to 98.9 lite/mil (26% increase) while with addition of nano-R-TiO\(_{2}\) at the same content, the abrasion resistance was significantly improved from 78.4 to 129.3 lite/mil (65% increase). After 48 aging cycles, the alkane CH groups and weight of the coatings without R-TiO\(_{2}\) particles, containing 2 wt.% micro-R-TiO\(_{2}\), containing nano-R-TiO\(_{2}\) lost 34.2% and 17.4%; 23.8% and 13%; 13.7% and 13%, respectively.