Cationic Epoxy Resin Research Articles

Experimental study of repairing rust-cracked reinforced concrete by electrophoresis deposition method

The rusting and cracking of reinforced concrete structures cost billions of dollars around the world every year, and there is a lack of targeted repair methods. In this study, we first put forward an electrophoretic deposition repair method using a high-performance colloid solution containing water-based cationic epoxy resin. The effect of electrophoretic deposition on rust-cracked reinforced concrete was studied. Then, the mesoscopic and microscopic morphologies of the repaired concrete surface, cracks, and defects at the interface of reinforced concrete were examined. Finally, the mechanism of electrodeposition was discussed, and the related reactions were summarized (ionization, electrolysis, electrophoresis, electrodeposition, electroosmosis, and curing reaction). The results show that electrophoretic deposition successfully increased the internal compactness, unconfined compressive strength, and split tensile strength of reinforced concrete, while greatly reducing the water absorption and the accelerated carbonation depth.

Effect of amination rate and neutralization degree of cationic epoxy resin on the repair effect of electrophoretic deposition

Cationic epoxy resin is an important basic material for electrophoretic deposition matching repair solution. This paper mainly studied the effects of amination rate and neutralization degree of cationic epoxy resin on electrophoretic deposition repairing effect of rust-cracked specimens, and analyzed the corresponding mechanism. The results show that the higher the amination rate and neutralization degree are, the faster the electrophoretic rate of molecules in the solution is, and the higher the deposition amount of epoxy resin on the specimen surface is. However, the higher the two parameters are, the waterproof performance of the repaired specimen will be worse.

Experimental Study on Repairing Corroded Cracks by Electrophoretic Deposition

The corrosion of reinforced concrete could reduce its mechanical properties and cause concrete cracking. Electrophoretic deposition is a new method for repairing rust-cracked reinforced concrete. In this study, we observed the crack surface morphology, mass growth, epoxy resin film thickness, ultrasonic rate, and epoxy resin filling depth of rust-cracked reinforced mortar specimens during the repair process and investigated internal microstructure and phase composition of the repaired mortar, and clarified the principle behind the electrophoretic deposition of cationic epoxy resin and curing agent molecules in the repair solution. The result of research shows that longer repair times decreased the carbonization depth and water absorption of the specimens. After repair, the porosity of the surface mortar decreased, owing to the filling of epoxy resin, and the newly generated epoxy resin film had a dense structure. Thus, the carbonization resistance and waterproof performance of the repaired specimens improved. The repair process of electrophoretic deposition can be divided into the immersion, repair, and curing stages, and the physical and chemical principles of each stage were explained.

Influence of cationic epoxy resin type on electrophoretic deposition effect on repair of rust-cracked reinforced concrete

This study proposed an electrophoretic deposition repair method to effectively repair and improve the durability of rust-cracked reinforced concrete structures, exploring the influence of cationic epoxy resin types on the repair process. After electrophoretic deposition repair, the carbonation resistance and waterproofing performance of the specimens improved significantly; as the repair in the solution of cationic epoxy resin molecular weight increased, the specimen surface crack healing rate and deposition rate increased; the larger the molecular weight of the cationic epoxy resin in the repair solution, the poorer the compactness of the repaired specimen, and the smaller the filling depth of epoxy resin.

Effect of colloid solution concentration of epoxy resin on properties of rust-cracked reinforced concrete repaired by electrophoretic deposition

An electrophoretic deposition technique is proposed for repairing rust-cracked concrete. A water-based cationic epoxy resin was used as the main base material of a high-performance epoxy resin colloidal (HERC) solution, focusing on the resulting concentration of electrophoretic deposition and post-repair performance metrics. Water and carbonation resistance of repaired specimens improved significantly with increased HERC concentration. Compressive strength and splitting tensile strength also improved. A microscopic morphology analysis showed that water and carbonation resistance, and strength of repaired specimens improved because a dense resin film structure formed on the crack surface, and resin was deposited and consolidated in the cracks, respectively.

SOL-GEL / DIP COATING TECHNIQUE FOR CORROSION PROTECTION OF PETROLEUM PIPELINE STEEL

In the oil, gas and petrochemical industries the greatest costs are those associated with material failures due directly to corrosive-erosive degradation of surfaces and components of the pipelines. These results in the frequent repair and replacement of parts which accrues costs associated with loss in revenues in downtime and maintenance [1]. In the current study, a dip-coating method was exploited to provide a coating layer of epoxy resin on 316L and 304 stainless steel plate. Epoxy resin was converted to cationic tertiary type amine resin. This cationic epoxy resin, which contains ammonium group in the end of the polymer chain, was synthesized by ring-opening reaction of an epoxy resin with secondary amine in the presence of a proton donor. A layer of resin was successfully deposited on the stainless steel plates and physical properties of the layer were assessed. A detailed study aiming to obtain reliable information of coating properties was carried out. The electrochemical corrosion results showed that epoxy layer has a positive behavior on protections of stainless steels alloys at the early degradation time point. Scanning electron microscopy observation was also used to study the surface morphology before and after coating. Tafel extrapolation method and Tafel slope constants were used to calculate the polarization resistance.

Influence of Cationic Epoxy Resin Type on Electrophoretic Deposition Effect on Repair of Rust-Cracked Reinforced Concrete

Influence of Cationic Epoxy Resin Type on Electrophoretic Deposition Effect on Repair of Rust-Cracked Reinforced Concrete

Monitoring of photopolymerization kinetics and network formation by combined real-time near-infrared spectroscopy and ultrasonic reflectometry

For in situ monitoring of fast changes of shear modulus and chemical conversion during UV radiation curing an ultrasonic (US) reflection method was combined with real-time near infrared (NIR) spectroscopy. The combined setup has been applied to study photopolymerization of different resins as acrylates, epoxy acrylates, acrylated polyurethanes and cationic epoxy resins in order to achieve a deeper understanding of the interdependence of reaction kinetics and changes of mechanical/rheological properties. The simultaneously recorded conversion–time and modulus–time curves allow differentiating between mass and diffusion controlled polymerization regime. Light curing and dark curing phases are indicated by two distinct regions in the conversion–time curves. By rescaling the curing time by chemical conversion modulus–conversion curves were constructed, which are described by combining a viscoelastic relaxation model with the conversion dependence of relaxation times. The NIR-US setup was used to study the influence of chemical composition and curing conditions on the polymer network formation.

The Effect of Sizing Agent of Carbon Fibre on the Interface of Electron Beam Cured Composites

To understand the effect of interface on the properties of electron beam cured composites, the composition and its chemical structure of the sizing agent of carbon fibres were investigated. The results show that there are alkali groups in the sizing agent of T300 and T800 carbon fibres, and these alkali groups react with the strong proton acids that are generated by the initiator and hinder the EB curing of cationic epoxy resin matrices. The properties of the composites of T300 and T800 carbon fibres cured by EB were poor. In the composites of T700, M40 and M40J carbon fibres, the effects of the sizing agent of the carbon fibres on the EB curing and the composite properties are less than for T300 and T800. After the carbon fibres were extracted by acetone, the properties of their composites improved. In particular, the heat-resistance and mechanical properties of composites of T300 and T800 carbon fibre increased greatly.

ELECTRODEPOSITION COATING OF EPOXY RESIN ON PHOSPHATED STEEL: OPTIMIZATION OF KEY FACTORS

Organic coating using electrodeposition method has attracted substantial attention in the last few years. This method of coating provides many advantages, including surface smoothness, less environmental pollution, and good performance of protection against corrosion. In the current investigation, an electrodeposition method was used to coat a uniform layer of epoxy resin on phosphated stainless steel plate. Epoxy resin was converted to cationic tertiary type amine resin. This cationic epoxy resin, which contains ammonium group in the end of the polymer chain, was synthesized by ring-opening reaction of an epoxy resin with secondary amine in the presence of a proton donor. The so prepared cationic resin was dispersed in water, giving an emulsion containing charged polymer particles. A layer of resin was successfully electrodeposited on the phosphated stainless steel plate and physical properties of the layer were studied. A detailed study aiming to obtain reliable information of coating properties was carried out. The effect of a number of factors, including electrodeposition voltage, electrodeposition time, pH value of the emulsion, solvent content, resin Epoxy Equivalent Weight (E.E.W.) resin concentration, and bath temperature on deposition yield and coating adhesion was studied with a view to optimize these factors. Variables affecting the rupture voltage were also investigated.

Epoxy-acrylic microgels in electrodeposition coating films

Epoxy-acrylic microgels (EAM) have been prepared via an aqueous dispersion polymerization of a mixture of acrylic monomers in the presence of the cationic soap with the quaternary ammonium salt groups and 2,2′-azobis(2-methylpropionitrile) (AIBN) as an initiator. The prepared microgels have a bimodal particle size distribution of 10 and 52 nm, and consist of a cross-linked acrylic polymer and cationic epoxy resin. Rheological data from the pendulum type rheovibron show that the presence of the spherical microgels in electrodeposition paint perturbs the flow of the surrounding fluid in a low shear field. A scanning electron microscope (SEM) showed that edge protection (%) at a knife blade increased proportionally with the amount of the microgel in the coating formulation. The microgels also provided excellent corrosion resistance; the cured film containing more than 7% microgels was free of rust spots after 168 h of the salt fog spray test. These results lead to the conclusion that EAM has a remarkable ability to perturb the thermal flow during the curing process and can be used in electrodeposition coating formulations to provide edge protection.

Coemulsion and electrodeposition properties of mixtures of cationic epoxy resin and cationic acrylic resin containing blocked‐isocyanate groups

Abstract2‐Ethylhexanol–half‐blocked‐toluene diisocyanate (2EH‐half‐blocked TDI) was first reacted with 2‐hydroxyethyl methacrylate (HEMA) to prepare HEMA–TDI–2EH monomer containing blocked‐isocyanate groups. This monomer was reacted with butyl acrylate, styrene, and N,N‐dimethylaminoethyl methacrylate to prepare an acrylic copolymer III′ containing blocked‐isocyanate groups and tertiary amine groups. The acrylic copolymer III′ can be mixed with an epoxy–amine adduct IV′, acetic acid, and deionized (D.I.) water to from an electrodepositable coemulsion. The electrophoretic codeposition of the coemulsion and physical and chemical properties of the codeposited film were investigated. The resin composition of film deposited from coemulsion was determined by Fourier transform infrared (FTIR) quantitative analysis to study the coemulsion and electrophoretic codeposition behavior. The applicability of this two‐component coemulsion in primer–surface (pricer) electrodepositable paint was also discussed. The results indicate that the deposition yield of cationic acrylic copolymer III is greater than that of cationic epoxy resin IV, i.e., the deposition velocity of III is faster than that of IV. However, resins III and IV can be well codispersed in D.I. water to form stable coemulsion; thus, the resin composition of deposited is almost equal to the resin composition. Moreover, the throwing power of coemulsion is almost equal to that of IV emulsion but greater than that of III emulsion. The optimum resin compositions of coemulsions for obtaining better gel content of deposited films are between 0.65 and 0.8 (III/III+IV, by weight). © 1994 John Wiley & Sons, Inc.

Fabrication of 3-D Models by CO2 Laser and Thermosetting Resin.

In our previous work, a method of fabricating solid models was developed by using an ultravioletlaser. It is intended in this study to apply a CO2 laser for making solid models, so as toreduce the cost of the system and the fabricating time. A thin liquid layer of cationic epoxy resin (thermosetting resin) was irradiated with CW CO2 laser light (9.5W, 10.6 μm) to be solidified. It was proved that irradiation with high power laser light caused explosive chain thermopolymerization, and the operating ranges for controllable reaction could be enlarged by fillinginert plastic powder in the resin. A solid model of 20 mm square in bottom and 10 mm in hightwas constructed by repeating laser radiation on resin over the solidified layer 20 times.

Coemulsion and electrodeposition properties of mixtures of cationic epoxy resin and cationic acrylic resin containing butoxymethylamide groups

AbstractButyl acrylate, styrene, N,N‐dimethylaminoethylmethacrylate, and N‐(n‐butoxymethyl) acrylamide were copolymerized to prepare a cationic acrylic copolymer (I) containing butoxymethylamide groups. This copolymer can be mixed with an epoxy‐amine adduct (II), acetic acid, and deionized (D.I.) water to form a coemulsion containing two cationic resins. The electrophoretic codeposition of the coemulsion and physical and chemical properties of the deposited film were investigated. The resin composition of film deposited from coemulsion was determined by Fourier transform Infrared (FTIR) quantitative analysis to study the coemulsion and electrophoretic codeposition behavior. The applicability of this two‐component coemulsion in primer‐surfacer (pricer) electrodeposition paint was also discussed. The results indicate that at any coemulsion resin composition the resin composition of electrodeposited film is almost equal to the coemulsion resin composition. The throwing power of emulsion increases with increasing applied voltage, as expected. However, the throwing power of coemulsion is almost equal to that of the II emulsion but greater than that of the I emulsion. Furthermore, all cured films derived from mixtures of I/II show excellent adhesive strength, good hardness, and high levels of salt spray resistance. © 1993 John Wiley & Sons, Inc.

Coemulsion and electrodeposition properties of mixtures of polyoxypropylene‐modified cationic epoxy resin and nonionic trimethylolpropane–toluene diisocyanate–2‐ethylhexanol crosslinker

AbstractThe emulsification and electrodeposition properties of mixtures of polyoxypropylene‐(POP) modified cationic epoxy resin (III) and nonionic trimethylolpropane–toluene diisocyanate–2‐ethylhexanol (TMP–TDI–2EH, V) were investigated and the compositions of their electrodeposited films were obtained by Fourier Transform Infrared (FTIR) quantitative analysis to study the effects of “soft segment” (oxypropylene groups) contained in resin III on the coemulsion and electrophoretic behavior. The results indicate that the deposition yield and throwing power of emulsion of resin III are highly dependent on its average molecular weight (Mw). Resin III with higher Mw has higher deposition yield but lower throwing power. Moreover, the deposition yield of V/III coemulsion also increases with increasing the Mw of III. On the other hand, the throwing power of V/III coemulsion is not related to the Mw of III but is influenced by the amount of soft segments in III. Increasing soft segment content in III increases the throwing power of the coemulsion. Furthermore, at the conditions providing stable coemulsion, the composition of the electrodeposited film is almost equal to the resin composition of the coemulsion. © 1993 John Wiley & Sons, Inc.

Coemulsion and electrodeposition properties of mixtures of a poly(oxypropylene)‐modified cationic epoxy resin and nonionic crosslinker system

AbstractThe emulsification and electrodeposition properties of mixtures of a poly(oxypropylene) (POP)‐modified cationic epoxy resin (III) and nonionic pentaerythritol/toluene diisocyanate/2‐ethylhexanol (PETOL‐TDI‐2EH, V) were investigated and the compositions of their electrodeposited films were obtained by Fourier Transform Infrared (FTIR) quantitative analysis to study the effects of soft segments (oxypropylene groups) contained in resins III on the coemulsion and electrophoretic behavior.The results indicate that the deposition yield and throwing power of an emulsion of individual III are deeply affected by its average molecular weight (AMW). Resin III with higher AMW has higher deposition yield but lower throwing power. Moreover, the deposition yield of V/III coemulsion also increases with increasing the AMW of III. On the other hand, the throwing power of V/III coemulsion is not related to the AMW of III but affected by the amount of soft segments in III. Increasing “Soft segment” Content in III increases the throwing power of coemulsion. Furthermore, at the conditions providing stable coemulsion, the composition of electrodeposited film is almost equal to the resin composition of coemulsion.

Synthesis and properties of cationic amine‐epoxy adducts and their use in electrodeposition, II. Diethanolamine/diketimine terminated cationic epoxy resins with pendent 2‐ethylhexanol‐blocked TDI groups

AbstractA diglycidylether of bisphenol A epoxy resin (DGEBA) was first reacted with 2,4‐toluene diisocyanate partially blocked with 2‐ethylhexanol (2‐EH P. B. TDI) to form modified epoxy resins, and subsequently reacted with different molar ratios of diethanolamine and bis(2‐methylisobutylketiminoethyl)amine (DKI) (used as ring opening agents) to give diethanolamine/diketimine terminated resins. These resins were hydrolyzed and neutralized with acetic acid to give cationic resins containing various contents of primary amine groups in the terminal polymeric chain. These cationic resins can be dissolved in a suitable solvent and mixed with deionized water to obtain emulsions. The electrodeposition properties and characteristics of the resulting cationic resins were investigated in detail. The effects of hydrophobic solvents, such as hexyl cellosolve (HCS) and toluene, on the deposition properties of the emulsions are discussed.