Epoxy-amine Coatings Research Articles

Comparative Studies of Wear and Corrosion Behaviors of Conventional and Nano Filler Based Solvent Free Tarfree Epoxy-amine Coatings

Tar-free epoxy coatings aid in protecting intact of Mild Steel (MS) substrate immersion condition of atmosphere. From lot of study revised and assorted that tar free (light colour) epoxy amine coating developed which give better performance for protection in long term. By ASTM method, wear behaviors as well as mechanical properties of quartz (micro silica) and organosiliane (nano silica) based tar-fee epoxy coatings were studied. DETA cured epoxy composites coatings were characterized by FTIR spectroscopic technique, powder X-Ray Diffraction (XRD), SEM and FESEM analysis. Transmission Electron Microscope (TEM) confirmed the size of nano particles. The data of wear index of nano fillers based epoxy coating was observed 8.3mg/1000cycles which indicate such an improvement of of abrasion behavior. Corrosion behaviors of the coated MSspecimens were evaluated by Cathodic Disbondment (CD) test immersion in 3.5% NaCl solution. Water absorption and chemical resistance also studied of composite coatings. All over tar-free epoxy-amine nano composite coating shows good result.

Cure Kinetics of Commercial Epoxy-Amine Products with Iso-Conversional Methods

The dependence of the apparent activation energy for the epoxy-amine reaction on the degree of conversion can be obtained by applying iso-conversional methods to the non-isothermal cure data obtained by using differential scanning calorimetry (DSC). The application of three iso-conversional methods has been utilized for the analysis of non-isothermal DSC cure data for three commercial high solids epoxy-amine coatings. The average apparent activation energy for cure of the fully formulated commercial product(s) is very similar to that previously reported for the epoxy-amine clear coats, indicating that the presence of additives does not influence the epoxy-amine apparent activation energy. Among the methods tested, Friedman’s method performed the best in fitting the experimental DSC data. In addition, all three methods underpredict the experimental isothermal cure data for three commercial products at two different cure conditions (i.e., 23 °C/50% RH and 40 °C/70% RH), showing that the non-isothermal DSC experiments cannot capture the catalytic effect of water on the curing reaction of epoxy-amine coatings. Furthermore, for high-solids epoxy-amine products, at least 60% conversion is required to achieve the time when the applied coating will not show any tackiness (i.e., the T2 time measured using the Beck Koller method).

The location of adsorbed water in pigmented epoxy-amine coatings

Pigmentation can exacerbate problematic water uptake into protective paints, leading to detrimental effects such delamination, swelling and plasticization. Potential underlying mechanisms include poor adhesion between the pigment and binder, the formation of hygroscopic interphase regions close to the pigment particles, and internal stress. Here, we demonstrate the use of nanoscale chemical mapping using AFM-IR and nanothermal analysis to investigate the contribution of these mechanisms directly for model coatings based on diglycidyl ether of bisphenol-A (DGEBA) cross-linked with triethylenetetramine (TETA). Whilst moisture uptake increases in the presence of a microscale silica matting agent, no chemical interphase could be detected close to the wax-coated particles. Instead, nanothermal analysis reveals attenuated thermal expansion of the polymeric binder and raised Tg values, supporting favourable polymer-pigment interaction and an increase in internal stress in the polymeric network. This is confirmed by mapping water distributions directly using AFM-IR, where no accumulation at the intact pigment-polymer interface/interphase is detected. Finally, further evidence is provided by bulk thermal analysis, where increased plasticization and desorption enthalpies demonstrate that water sorption into the bulk polymer binder increases as a function of added pigment volume concentrations.

Unravelling the chemisorption mechanism of epoxy-amine coatings on Zr-based converted galvanized steel by combined static XPS/ToF-SIMS approach

This work aims at the elucidation of the interfacial interactions established between an epoxy-amine coating and hot-dip galvanized (HDG) steel. The influence of the Zr-based conversion treatment of the substrate and the use of the Cu(II) additive on interfacial bonding is studied. To this purpose, an amine-functionalized molecule – diethylenetriamine (DETA) – is adsorbed. The complex multi-metal oxide surface of the Cu-modified Zr-based converted substrate is decomposed in derivative (simpler) systems. The resulting DETA-adsorbed model and multi-metal surfaces are investigated by X-ray photo-electron spectroscopy (XPS), and by examination of the N 1s peak, the interfacial bond density is determined. Time-of-flight secondary ion mass spectrometry (ToF-SIMS) is performed to discriminate between the different metal oxide contributions present on the substrate surface. Preferential adsorption of the DETA molecule on the zinc atoms is found on converted substrates. The interfacial bonding with the Cu cationic sites introduced by the copper additive is proven.

Comparison of new bio-based epoxide-amine coatings with their nanocomposite coating derivatives (graphene, CNT, and fullerene) as replacements for BPA

As replacements for BPA, new bio-based epoxy-amine coatings and their nanocomposite coating derivatives including graphenes, carbon nanotubes (CNTs) and fullerenes were prepared for the first time, and their thermal and mechanical properties have been compared.A Diels Alder reaction was employed to prepare epoxy-functionalized tung oil (ETO). As a curing process, a primary diamine hardener (Jeffamine D2000) was used at four different temperatures ranging from 25 °C to 150 °C. Epoxide-amine nanocomposites were prepared with a 1:1 epoxy: amine molar ratio and additive of carbon nanoparticles (graphenes, carbon nanotubes (CNTs) and fullerenes).The cured coatings were analyzed by IR, DSC, TGA, and gel-content tests. Thermal stability of new coatings is observed up to 430 °C according to TGA analysis and these cured films displayed two glass transition points (Tgs) by DSC. While, of the three nano-composite incorporated systems, the graphene systems gave the maximum Tg in both phases, and the CNT-system exhibited a higher Ts and lowest weight loss with residues ranging up to 60% at 800 °C.The determination of the mechanical properties of the cured coatings was accomplished by pendulum hardness, pencil hardness, pull-off adhesion, cross-hatch adhesion, impact and reverse impact resistance tests. All the cured coatings have good mechanical properties in terms of hardness, cross-hatch adhesion and impact resistance. Generally, epoxide-amine nanocomposite coatings displayed better thermal and mechanical properties in comparison to epoxide-amine coatings.

Reversible hetero-Diels–Alder amine hardener as drop-in replacement for healable epoxy coatings

Replacing commercial hardeners with bio-sourced fatty acids linked by hetero Diels–Alder (HDA) motifs enabled epoxy-amine coatings with intrinsic self-healing properties. The HDA-based coatings demonstrate scratch healing at 95 °C within 15 min.

Protective primers with reduced zinc powder content caused by the addition of core-shell micro talc/polyaniline pigment

This study aims to verify the possibility of replacing a portion of zinc (up to 30 wt.%) with a newly designed micro talc/polyaniline (PANI) core-shell pigment that can be used in the protective primer compositions for metals. Measurements of the electrode potential of painted steel and the electrical capacity of the steel/coating/electrolyte system showed that synthesized pigment bears two functions. Firstly, its presence in the epoxy-amine coatings provides a cathodic protection mechanism for steel with the lower zinc content. Secondly, it allows long-term preservation of the sacrificial metal activity and passive state of the substrate due to the autocatalytic redox cycle based on the reversible conversion of PANI from its emeraldine to leucoemeraldine form. The corresponding mechanism that allows the retaining of sacrificial metal activity and the passive state of the substrate is proposed.

Investigation of adhesive-strength characteristics of fire-retardant epoxy polymers modified with metal-containing additives

Composite materials based on epoxy oligomers due to their unique properties are widely used in various fields of construction and mechanical engineering, including fire retardant coatings. The introduction of flame retardants and dispersed inert fillers as a rule, affects the structure of epoxy polymers. When addressing issues related to the creation of flame-retardant, composite materials, there is insufficient data on the impact of dispersed mineral fillers on their performance properties. Attention is mainly paid to the indicators of flammability, toxicity of combustion products and thermophysical properties of the coating. Therefore, the aim of this work is to conduct experimental studies of changes in the adhesive and strength characteristics of fire-retardant epoxy polymer from the content of metal-containing additives. As a result of experimental studies, it was found of that changing the component composition of the composition can vary widely the adhesive strength characteristics of fire-retardant epoxy polymers. The obtained data must be taken into account when developing epoxyamine coatings for fire protection of building structures and technological communications.

The Effect of Extender Particle Size on the Glass Transition Temperature of Model Epoxy Coatings.

Inorganic extenders are important constituents of 2K thermosetting epoxy-amine coatings and their physical properties play an important role in the final properties of the organic coatings. The effects of extender particle size and loading (i.e., the amount of extender in component A or in the total formulation) on the glass transition temperature (Tg) of model epoxy-amine coatings were studied in this work with differential scanning calorimetry (DSC) and dynamic mechanical analysis (DMA). The obtained results show that the particle size and loading of feldspar particles (from 25 wt% to 70 wt%) do not influence the glass transition temperature of the model epoxy-amine coating significantly. In general, the smaller the particle size the lower the glass transition temperature of the coating but this depression in Tg seems negligible when seen relative to the change in extender particle size. Similar observations are reported for two model coatings having the same lamda (Λ) value but with silica of very different particle sizes (i.e., nanosilica and micron sized silica).

Exploring Whether a Buried Nanoscale Interphase Exists within Epoxy–Amine Coatings: Implications for Adhesion, Fracture Toughness, and Corrosion Resistance

Epoxy resins remain some of the most widely used industrial materials, comprising the matrix component of many paints, adhesives, and structural composites. Extensive interphase structures within e...

Anticorrosive Performance of New Epoxy-Amine Coatings Based on Zinc Phosphate Tetrahydrate as a Nontoxic Pigment for Carbon Steel in NaCl Medium

Epoxy resin is known to react with a hardener such as polyamine to form a thermoset 3D polymer net with an outstanding physical and mechanical properties. They are widely used in coating and adhesives. In this study, we present a new epoxy resin material useful for making an anticorrosive formulation for carbon steel. The epoxy resin presented in this study is diglycidyl ether 4, $$4^{\prime }$$ -dihydroxy diphenyl sulfone (DGEDDS). It was prepared in a two-step process that involves reacting epichlorohydrin with 4, $$4^{\prime }$$ dihydroxy diphenyl sulfone then with sodium hydroxide. The structural elucidation of DGEDDS was carried out with Fourier transform infrared. The anticorrosive formulation DGEDDS–MDA–ZPH was prepared from DGEDDS and the hardener 4, $$4^{\prime }$$ -methylene dianiline (MDA) in the presence of the anticorrosion pigment zinc phosphate tetrahydrate (ZPH). Another standard formulation (DGEDDS–MDA) was prepared without ZPH. The physicochemical and anticorrosive performance of the coated carbon steel was evaluated using electrochemical impedance spectroscopy (EIS). The coated surface was subjected to morphological characterization by SEM before and after immersion in the corrosive medium and exposing it to the UV radiation. The value of the polarization resistance ( $$R_{\mathrm{p}}$$ ) obtained by the EIS method for the standard coating DGEDDS–MDA and epoxy composite coating DGEDDS–MDA–ZPH was 31898 and 72611 $$\Omega \,\hbox {cm}^{2}$$ during the 1 h of immersion in 3 wt% NaCl, respectively. After aging by exposing the coatings for a 2000 h to UV radiation the values were dropped to 2596 and 5189 $$\Omega \,\hbox {cm}^{2}$$ , respectively. The values show the high stability and resistance of the epoxy resin coating to electrolytes and UV radiation. The coating even showed higher stability in the presence of ZPH pigment. As shown in the results, the tricomponent composite showed an outstanding stability in protecting carbon steel form corrosion in an aggressive marine environment where UV is very intense and the humidity and salts are very high.

Superior relaxation of stresses and self-healing behavior of epoxy-amine coatings

Introducing hydrogen bonds via amide motif incorporation in cross-linked epoxy coatings enhances local network mobility and ensures ability to relax mechanical stresses, possibly leading failure, preemptively without changes in modulus and adhesion.

Extreme wet adhesion of a novel epoxy-amine coating on aluminum alloy 2024-T3

Amine-epoxy polymer systems are widely used, for example as matrix materials for structural composites employed in aerospace industry and in industrial coatings on metal substrates for corrosion protection. This work focuses on the investigation of different epoxy-amine coatings on the adhesion performance on aluminum AA-2024 substrates. Two different epoxies (Epikote 828 (aromatic) and Eponex 1510 (aliphatic)) and four different amines (1,8-diaminooctane, Dytek A, Jeffamine EDR148 and Jeffamine D230) as curing agent were used in different stoichiometric ratios. These different epoxy-amine coatings were characterized using differential scanning calorimetry (DSC), dynamic mechanical analysis (DMA), tensile tests (pull-off) and water-uptake measurements. Pull-off tests in dry conditions showed comparable adhesion of the coatings. Surprisingly, pull-off results showed after water soaking a higher wet adhesion of the coatings prepared with Eponex 1510 as compared to coatings prepared with Epikote 828. Moreover, the combination of Eponex 1510-Jeffamine EDR148 coatings resulted in high adhesion values (∼7MPa) with pull-off tests and these values did not change after immersion for two weeks in water. This combination shows extreme good wet adhesion performance as compared to any other epoxy-amine coating. Complete recovery was demonstrated of the adhesion of Eponex 1510-Jeffamine D230 coating after being immersed for two weeks in water and dried for two weeks. Furthermore, in contrast with Epikote 828 water uptake measurements showed almost nil water uptake for all coatings prepared with Eponex 1510. Optical microscopy investigations on the residues of the coatings after pull-off tests revealed adhesive failure in wet condition for Epikote 828, while coatings prepared with Eponex 1510 showed cohesive failure.

Silicon-containing amine curing agents and their application to protective epoxide compositions

Novel silicon-containing amine curing agents for epoxy oligomers were synthesized by the interaction of diols of variable structure with aminopropyltriethoxysilane. The development of these curing agents yields a significant reduction in the polymer glass point, an increase in the degree of conversion of epoxide groups in the course of curing, and a significant improvement in the chemical stability and hydrophobicity of epoxy amine coatings, as well as their physicomechanical properties.

Adding value to coatings by using unique organofunctional silicone hybrids

The modification or replacement of polyurethane binders with unique amino and epoxy functional silicone hybrid coatings improves significantly the UV light and chemical resistance of industrial, shipbuilding and architectural coatings. In particular the upgrading of standard epoxy-amine coatings with new silicone hybrids improves the performance to that of urethane technologies. The replacement of Si-O-C bond with Si-C-C bond in silicone hybrids increases the weather resistance and the coatings ability to withstand exposure to harsh chemicals such as sulfuric acid, phosphoric acid, hydrochloric acid and ammonium hydroxide. In addition, the unique structure of organofunctional silicone hybrids increases the coatings resistance to graffiti, dirt pick-up and biological growth.

Properties of epoxy-amine coatings modified with petroleum polymeric resins

We study the composition of the gel fraction, water absorption, and impedance characteristics of epoxy coatings modified with petroleum polymeric resin treated with maleic anhydride. It is shown that modified epoxy coatings are characterized by higher water resistance and better protective properties in acid media. We determine the optimal amount of the petroleum polymeric modifier and demonstrate the possibility of improvement of the corrosion resistance of modified epoxy coatings by subsequent thermal treatment.

Laser Raman method for the study of the homogeneity of epoxy-amine coatings

On utilise une microsonde a laser Raman pour etudier l'homogeneite de films de melanges de resines epoxydes et aminees deposes sur de l'acier

The application of x-ray photo-electron spectroscopy to a study of interfacial composition in corrosion-induced paint de-adhesion

Interfacial surfaces generated by corrosion-induced de-adhesion of organic coatings on bare steel have been analyzed by X-ray photo-electron spectroscopy (XPS). XPS elemental analyses have been used to provide an initial overview of changes in composition relative to untested surfaces; high resolution XPS spectra have been used to provide more detailed, sometimes semi-quantitative, analyses of molecular functional group composition. The high resolution spectra of specimen surfaces have been compared with each other and with reference compounds qualitatively and, in more detail, by calculating difference spectra and binding energy differences. Curve resolution methods have been employed to estimate functional group compositions. Corrosion-induced de-adhesion is associated principally with cathodic corrosion reactions and reaction products, including hydroxide. Epoxy ester-based coating interfacial surfaces have been demonstrated to bear (in addition to undegraded resin) carboxylate moieties indicative of ester saponification. For model epoxy-urethane and epoxy-amine coatings, a substantial carbonate residue is deduced. This residue is attributed to degradation of urethane and urea moieties. In addition, the presence of polymer residues on the interfacial substrate surfaces is demonstrated. It is concluded that de-adhesion involves substantial cohesive failure of the coating resin in the interfacial region.

Laboratory Tests Show Resistance Properties of Urethane Coatings

Abstract Describes the basic differences in major types of urethane surface coatings commercially available. Illustrates considerable variation in chemical resistance of commercial formulas in two-package or catalyzed urethane group. Describes superior resistance of catalyzed urethanes to softening by high-solvency organics as compared to commercial epoxyamine coatings. Illustrates urethane retention of flexibility and impact resistance after weathering exposures as compared to commercial catalyzed epoxies. Describes briefly several types of urethane coatings that are being developed.5.4.5