Synthesis and Characterization of Waterborne Epoxy Curing Agent Modified by Silane

A novel waterborne epoxy curing agent was prepared using 3-glycidoxypropyl trimethoxysilane （GPTMS） as a termination agent of adduct, which was synthesized by triethylene tetramine （TETA） and liquid epoxy resin （E-51）. The effects of the reaction temperature and time on the synthesis process were investigated experimentally. The particle size and the distribution of water dispersion of the curing agent were measured by dynamic light scattering（DLS）. The structure of the products was characterized by Fourier transform infrared spec-trometer （FTIR） and ^1H-nuclear magnetic resonance （^1H NMR）. The properties of the synthesized curing agent and the epoxy resin film cured by it were also measured. The results showed that the appropriate temperature for the synthesis of adduct was at 65-75℃ and the reaction time was 4-5h, and that the suitable reaction temperature of curing agent synthesis was 75-85℃ and the reaction time was 3-4h. When the mass ratios of GPTMS and acetic acid were 3%-5% and 5%-10% respectively, the hardness, water resistance and adhesion of the cured film were improved significantly.

Waterborne Epoxy Resin Modified by AMPS

A stable epoxy emulsion was prepared with epoxy resin （EP） as raw material, 2-acrylamido-2- methyl-l-propanesulfonic acid （AMPS） as modifier and benzoyl peroxide as initiator. By criterion of yield of the copolymer AMPS-EP, water-solubility, change of the acid value and intrinsic viscosity [η] along with reaction time, the copolymerization course was deduced. It is found that during the process, AMPS takes part in both the grafting copolymerization with epoxy principal chain and the ring-opening polyaddition with epoxy group. It is also discovered that the yield of AMPS-EP and water dispersing varies with reaction time. When it reaches 1.5 h, AMPS-EP can obtain good water-solubility; but the water-solubility will go bad gradually if it exceeds 3.5 h.. R spectrum analysis indicates that partial epoxy group partially remains and the others create sulfonic ester.

Effect of Nano Al Pigment on the Anticorrosive Performance of Waterborne Epoxy Coatings

This paper presents the results regarding the effect of nano aluminum powder pigment concentration on the protective properties of waterborne epoxy films in 3.5 wt pct NaCl solution. The anticorrosive performance of the coatings with 0.5, 1, and 3 wt pct pigments and none pigment were investigated using electrochemical impedance spectroscopy （EIS）, scanning electron microscopy （SEM） and Raman spectroscopy techniques. The results show that adding appropriate amount of nano-aluminium powder pigment can enhance the barrier properties of the epoxy coating, which is attributed to the surface effect of nanoparticles and the compatibility of the pigment with the waterborne epoxy coatings.

Mechanism Analysis of Stiffness Improvement by Waterborne Epoxy Resin Surface Sizing Agent

Low-basis-weight paper lacks normal strength and stiffness. Waterborne epoxy resin could be employed with oxidized starch to improve paper stiffness through surface sizing. In this study,the mechanism of enhancing stiffness by adding waterborne epoxy resin was fully investigated. The results indicated that through surface sizing with epoxy resin,the paper thickness was preserved,whereas the elastic modulus increased significantly and the epoxy resin had positive impact on single fiber strength. A rigid resin layer and interpenetrating polymer network formed on the surface and in the inner layer of the paper,respectively. The formed resin layer and interpenetrating polymer network strongly supported the paper,leading to the improvement of the elastic modulus and stiffness. The stiffness improvement through surface sizing was mainly due to the formation of a fibrous composite layer and penetration of the sizing agent into the inner layers of the paper. The better the combination between fiber and sizing agent,the higher were the elastic modulus and the stiffness of the whole paper.

Compatibility evaluation between waterborne epoxy resin and SBR latex modified asphalt emulsion

Good compatibility between waterborne epoxy resin(WER)modifier and styrene-butadiene rubber(SBR)latex modified asphalt emulsion(SBRE)is an essential premise for good pavement performance of WER and SBR latex compositely modified asphalt emulsion(WSAE).This study aims to explore the compatibility between WER modifier and SBRE.To achieve the goal,several WER modifiers produced by two methods were first selected to modify SBRE,thus the WSAEs were prepared.Next,storage stability and workability of the WSAEs themselves,and high-temperature performance,rheological behavior and temperature sensitivity of their evaporated residues were compared and evaluated via performing a series of experiments,respectively,thus the WER modifier possessing an optimal modification effect was recommended.Results show that the storage stability of WSAEs is sensitive to the amount of WERs.The incorporation of 1%WERs by the mass of SBRE improves the storage stability of SBRE,while WERs that exceed 1%weaken its storage stability.When the WERs reach 3%and 4%,the 5 d storage stability of prepared WSAEs will be beyond the limitation of specification.Incorporating WERs into SBRE negatively affects the workability of SBRE,and the workability of WSAEs is adversely influenced by the WERs content and the storage time.To ensure the construction,the WSAEs with 3%and 4%WERs should not be stored for more than 36 h and 48 h,respectively.The WERs effectively improve the high-temperature performance of SBRE residue,especially the 3%WERs.Besides,the WERs notably enhance the rheological property and thermal stability of SBRE residue.In contrast,the WER modifier produced by chemically modified method has a smaller adverse impact on the storage stability and workability of WSAE,and a larger enhancement on the high-temperature performance,rheological property and thermal stability of SBRE residue,which is thus recommended to modify SBRE.

Amino-functionalized Ti_(3)C_(2)T_(x) with anti-corrosive/wear function for waterborne epoxy coating

Two-dimensional Ti_(3)C_(2)T_(x) flakes have great application potential in various areas due to their optical,electronic,electrochemical and mechanical properties,but their anti-corrosion and wear-resistance performance were not well understood.The difficulties in achieving good dispersity and interface interaction of inorganic additives in organic coatings hinder the incorporation of Ti_(3)C_(2)T_(x) into the epoxy coating.Here,few-layered Ti_(3)C_(2)T_(x) sheets with amino-functionalization were prepared,and as reinforced-additives were added into the waterborne epoxy coating.Anti-corrosion and tribological properties of as-prepared composite coatings were investigated in detail.The results reveal that the composite coating with 0.5 wt.%amino-functionalized Ti_(3)C_(2)T_(x) sheets shows excellent corrosion protection(the lowest frequency impedance was 3.12×10^(9) cm^(2))and wear resistance(wear rate was reduced by 72.74%).The greatly improving performance of composite coatings mainly depends on:(a)good dispersity and compatibility of amino-functionalized Ti_(3)C_(2)T_(x) in organic matrix,(b)high adhesion strength between coating and metal substrate and(c)the intrinsic properties of Ti3C2Tx sheets.The work provides a good path for applications of MXene as multifunctional additives.

Graphene-induced enhanced anticorrosion performance of waterborne epoxy resin coating

In this work,waterborne epoxy resin E44 and graphene were employed as the matrix and nanofiller,respectively,to construct composite coatings with enhanced anticorrosion performance.XRD pattern and TEM observation indicated that the obtained graphene had a stacked structure of few-layer graphitic sheets with numbers of wrinkles.SEM observations revealed that no defects or microcracks existed on the surface of graphene/epoxy coatings and the internal micropores and microcracks were filled by graphene.FTIR spectra displayed that all the characteristic absorption peaks were attributed to the epoxy resin cured with polyamide.The Tafel polarization curves showed that,as the graphene addition amount increased,the corrosive potential increased and the corrosive current decreased.ESI results proved that the addition of graphene into epoxy coatings could not only increase the impedance arc in Nyquist plots,but also increase the impedance modulus at low frequency.Finally,the enhanced anticorrosion mechanism was proposed and discussed.

Corrosion Resistance of Graphene-Reinforced Waterborne Epoxy Coatings

Graphene （G） was dispersed uniformly in water and used as an inhibitor in waterborne epoxy coatings. The effect of dispersed G on anticorrosion performance of epoxy coatings was evaluated. The composite coatings displayed outstanding barrier properties against H20 molecule compared to the neat epoxy coating. Open circuit potential （OCP）, Tafel and electrochemical impedance spectroscopy （EIS） analysis confirmed that the corrosion rate exhibited by composite coatings with 0.5 wt% G was an order of magnitude lower than that of neat epoxy coating. Salt spray test results revealed superior corrosion resistance offered by the composite coating.

A facile approach to fabricating graphene/waterborne epoxy coatings with dual functionalities of barrier and corrosion inhibitor

A facile and environmentally-friendly method is developed to prepare graphene/waterborne epoxy(WEP)composite coatings.The graphene nanosheets are produced with electrochemical-exfoliation in the solution containing surfactants,cetyl trimethyl ammonium bromide(CTAB)and sodium dodecyl sulfate(SDS).The nanosheets containing solution thus formed are subjected to a quick dialysis and then directly used as a diluent for WEP without any further treatment.This preparation method overcomes the commonly identified problems of aggregations and‘corrosion promotion’effect associated with graphene,and increases the impedance of the composite coatings by more than two orders of magnitude.The analysis of anticorrosion performance suggested that the presence of surfactants not only improves the dispersibility of graphene nanosheets but also endows the composite coatings with both barrier and corrosion inhibition capabilities.The strategy reported herein may pave the path to the large-scale production of graphene anticorrosion coatings.

Effect of Waterborne Epoxy on Performances of Cement Asphalt Mortar

The waterborne epoxy modified cement asphalt mortars were prepared with varying content waterborne epoxy and a constant fluidity. The effects of waterborne epoxy emulsion on water/cement ratio,compressive and flexural strength,tensile bond strength,freezing and thawing damage,corrosion resistance of cement asphalt mortar cured for 7 and 28 d have been investigated. The results show that waterborne epoxy is very beneficial to the improvement of mechianical properties and durability of cement asphalt mortar. Waterborne epoxy can improve the flowing ability of cement asphalt mortar. With the increasing of waterborne epoxy content,compressive strength,flexural strength and bond strength all have increased obviously. The modified mortar shows higher resistance to corrosion and the freezing and thawing compared with control mortar.

RHEOLOGICAL BEHAVIOR OF EPOXY RESIN WATERBORNE DISPERSIONS

The waterborne dispersions of epoxy resin were prepared by the phase inversion emulsification technique. Rheological behavior and its relationship with the structural change of the systems were studied. It was shown that the concentrated dispersions were highly viscoelastic and pseudoplastic, which was attributed to the formation of a physical network among the waterborne particles via hydrogen bond. The dilute dispersions were Newtonian fluids. The discrete clusters composed of small waterborne particles were found in diluted dispersions. With increasing solid content, there existed a structural transition via percolation through a cluster-cluster aggregation mode to form the physical network, which was qualitatively evidenced by the TEM morphologies.

Facile recycling of anhydride-cured epoxy thermoset under mild conditions with multifunctional hydrazine hydrate

Environmental economics is accelerating the urgency to develop recycling technologies for the ever-growing quantity of discarded thermoset polymers.Herein,we developed a mild and energy-saving pro-cess for high-eficiency degradation and reuse of anhydride-cured epoxy thermoset with the aid of hy-drazine hydrate.The degradation degree of the epoxy resin reached 99.6%at 120℃ within a short time of 60min.During the reaction,the ester bonds in the cross-linked network were selectively cleaved by the amination of hydrazine hydrate,and the epoxy resin was fully converted to new monomers that con-tained hydrazide and hydroxyl groups,respectively.Moreover,the degradation mechanism of the epoxy resin in hydrazine hydrate was studied and a nucleation model was utilized to predict the actual degra-dation behavior of the system.Finally,the degradation products can be directly mixed with epoxy precur-sor to prepare a new waterborne epoxy coating with good comprehensive properties.This work not only demonstrates a new way to realize the efficient degradation of epoxy resins,but also provides a facile and efficient recycling protocol for thermosets.