Curing Behavior Of Epoxy Resin Research Articles

Diatomite‐filled epoxy resin composites: Curing behavior, dielectric, and thermal properties

AbstractIn this study, a kind of novel curing agent composed of acrylic acid and 4,4′‐(hexafluoroisopropylidene)bis(p‐phenyleneoxy)dianiline was mixed, with different contents of diatomite (CP) particles, into the epoxy resin (E51) to obtain bio‐composites that can be rapidly molded and cured at room temperature. Fourier Transform Infrared Spectroscopy and Differential Scanning Calorimetry were used to study the curing behavior of epoxy resin and bio‐composites. The influence of CP particle dosages on the mechanical, including tensile, flexural and impact properties, and thermal properties of the prepared composites were discussed. Thermogravimetric analysis result showed that the thermal stability increased with increasing of CP fillers content. Dielectric property tests confirmed that the dielectric constant of composites decreased attributed to the incorporating of novel curing agent and CP fillers with porous structure into epoxy resin. Finally, Scanning Electron Microscope revealed the excellent adhesion between the cured resin and the fillers.

Preparation and characterization of waterborne epoxy modified bitumen emulsion as a potential high-performance cold binder

This study aims to explore the feasibility of using waterborne epoxy modified bitumen emulsion (WEB) as a high-performance cold binder through chemical analysis and performance characterization. To achieve this objective, waterborne curing agent was first synthesized and characterized by Fourier transform-infrared spectroscopy (FT-IR) and Zetasizer. Then, FT-IR analysis was conducted to monitor the curing behaviour of epoxy resin in bitumen emulsion. Following the moisture susceptibility tests of bitumen emulsion mixture through the boiling tests, the rheological properties of WEB residues were characterized through the dynamic shear rheometer (DSR) tests. Finally, linear amplitude sweep (LAS) analysis was conducted to evaluate the fatigue resistance of the bitumen emulsion residues. The results indicated that the incorporation of waterborne epoxy resin into bitumen emulsion significantly improved its adhesion performance, mechanical strength, and fatigue life, making WEB a potential high-performance cold binder for various application purposes, such as cold recycling and cold-mix asphalt paving.

Isotropical conductive adhesives with very-long silver nanowires as conductive fillers

Isotropical conductive adhesives (ICAs) have garnered great attention from the researchers in electronic industry as a potential substitute to lead-bearing solders for novel microsystem. In this paper, silver nanowires with a diameter of approximately 390 nm and a length of over 100 μm were synthesized by a polyol process. The ICAs composed of an epoxy-based binder containing silver nanowire were prepared and the curing behaviors, electrical properties, hygroscopicity, and the tensile shear strength of ICAs were investigated. Silver nanowires affect the curing behavior of epoxy resin and reduce the cross-linking density. The resistivity of the ICAs filled with 10, 35 and 45 wt% silver nanowire cured at 150 °C is 8.9 × 10−3, 1.69 × 10−5 and 4.9 × 10−6 Ω cm respectively. The resistivity of the ICAs filled with silver nanowire cured at 150 °C is little change after aged under 85 °C/85 % for 264 h. With the increase of the loading of silver nanowire the tensile shear strength of the ICAs increase. The reasons for the effects of silver nanowires on the curing behavior and the electrical property and hygroscopicity and the tensile shear strength were discussed in terms of the morphology, distribution, and higher activity of silver nanowires.

Anticorrosive performance of epoxy/clay nanocomposites pretreated by hexafluorozirconic acid based conversion coating on St12

In this research, epoxy composites were prepared using different loadings (0.5, 0.8, 1, 2 and 3 wt-%) of clay nanoparticles. Fourier transform infrared spectroscopy was utilised to investigate the curing behaviour of epoxy resin. The quality of dispersion and the distribution structure of nanoclays in coating were studied by visual observations and X-ray diffraction in detail. Corrosion resistance behaviour of epoxy coating containing various clay percentages was investigated on steel by electrochemical impedance spectroscopy. Moreover, the modification of substrate was accomplished using conversion coating based on hexafluorozirconic acid. The electrochemical results revealed that the pretreated coating with 3 wt-% nanoclays possesses the best anticorrosive performance (2.5×108 Ω cm2) after 2 weeks immersion in 3.5 wt-%NaCl solution. The morphological properties of conversion coating were observed by a field emission scanning electron microscope. In addition, pull-off technique was employed to measure the adhesion strength of coatings to metallic substrate. Experimental results exhibited that optimum clay loadings and conversion coating impressively increased the corrosion resistance and coating adhesion as well.

Curing Behavior of Epoxy Resin by Phosphate Salts as Thermal Latent Hardener

<b>Curing Behavior of Epoxy Resin by Phosphate Salts as </b><b>Thermal Latent Hardener </b>

Curing Behavior of Epoxy Resins with Cyclic Amidine Derivatives

<b>Curing Behavior of Epoxy Resins with Cyclic Amidine Derivatives </b>

Effect of Carboxyl Functionalized MWCNTs on the Cure Behavior of Epoxy Resin

Effects of carboxyl functionalized MWCNTs on the cure behavior of epoxy resin (EPIKOTETM resin 862 and EPICURETM curing agent W) were investigated by using differential scanning calorimeter in dynamic scan mode. Results indicated that nanotubes could initiate cure reaction at lower temperature while only 0.1 wt% samples were able to suppress the peak temperature (Tp) consistently regardless of different heating rate due to their higher reaction rate, other two batches (0.2 wt% and 0.3 wt% CNT) showed hardly any change in Tp compared to neat samples. Furthermore, addition of small amount (0.1 wt%) of CNTs significantly reduced the activation energy of the system but further addition elevated that due to their retarding effect. Also, a correlation was established between the dispersion state of CNTs in epoxy and total heat of reaction (ΔH) where lower ΔH was considered as an indication of better interfacial interaction of CNTs with matrix and hence, better dispersion. The difference in curing behavior of three different CNT percentages was discussed in terms of their steric hindrance and state of dispersion in the matrix.

Shelf stability of reactive adhesive formulations: A case study for dicyandiamide-cured epoxy systems

Positron annihilation lifetime spectroscopy was used to study the curing behavior of epoxy resins of DGEBA with a hardener of dicyandiamide, from the initial viscous state of the formulation to the cured polymer. Isothermal measurements were done in the range from 50 to 80 °C. Gelation resulted in an increase of the intensity of ortho-positronium ( o-Ps) and a sharp decrease in the lifetime. Change of o-Ps lifetime was used as a measure for the degree of curing. Applying the Johnson–Mehl–Avrami–Kolmogorov approach, these changes could be characterized and growth exponent ‘ n’ and reaction constant ‘ k’ were determined. Hence, we are able to project the shelf life of this one-component epoxy at room temperature by extrapolation.

Curing behavior and kinetic analysis of epoxy resin/multi-walled carbon nanotubes composites

The effect of multi-walled carbon nanotubes (MWNTs), both amino-functionalized (f-MWNTs) and unfunctionalized (p-MWNTs) on the curing behavior of epoxy resin (EP) cured with triethanolamine (TEA), was investigated using differential scanning calorimetry (DSC). Because the triethylenetetramine (TETA) grafted on the f-MWNTs could act as curing agent and the produced tertiary amine as negative ionic catalysts of curing reaction of EP, so the activation energy of the EP/TEA system was decreased by the addition of f-MWNTs. Viscosity played a key role in the curing behavior of the EP/TEA/MWNTs system, for high viscosity of the EP/TEA/MWNTs system could hinder the motion of the functional groups. The curing heat in EP/TEA/f-MWNTs (weight ratio 1/0.1/0.01) system was higher than the neat EP/TEA (weight ratio 1/0.1) system, while the curing heat in EP/TEA/p-MWNTs (weight ratio 1/0.1/0.01) was lower than the neat system. When the content of f-MWNTs was increased to 2 phr (weight ratio of 1/0.1/0.02), the curing heat became lower than that of the neat EP/TEA system, which was the result of the higher viscosity of the EP/f-MWNTs/TEA system. Since the curing heat indicated the curing degree of the system generally, the addition of the f-MWNTs was thought to increase the curing degree of the epoxy matrix at a relatively low content.

Cure behavior of epoxy resin containing castor oil and cashew nut shell liquid and its derivative

AbstractThe cure behavior of epoxy resin with a conventional amide‐type hardener (HD) was investigated in the presence of castor oil (CO), cashew nut shell liquid (CNSL), and cashew nut shell liquid–formaldehyde resin (CFR) with dynamic differential scanning calorimetry (DSC). The activation energy of the curing reaction was also calculated on the basis of nonisothermal DSC thermograms at various heating rates. A one‐stage curing was noted in the case of epoxy resin filled with CO, whereas the epoxy resin with CNSL and CFR showed a two‐stage curing process. A competitive cure reaction was noted for the epoxy resin/CNSL(or CFR)/HD blends. In the absence of HD, CFR showed lower values of curing enthalpy than that of CNSL. The activation energy of epoxy resin curing increased with increasing CNSL and CFR loading. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 2007