Paper-IV-Polymer Engineering and Science (original) (raw)
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Understanding the thermal, mechanical and electrical properties of epoxy nanocomposites
Materials Science and Engineering A-structural Materials Properties Microstructure and Processing, 2007
In the present work, the electrical, mechanical and thermal properties of epoxy nanocomposite materials were studied. The electrical insulation characteristics were analyzed through short time breakdown voltage test, accelerated electrical ageing test, and by tracking test. The breakdown voltage increases with increase in nano-clay content up to 5 wt%, under AC and DC voltages. The volume resistivity, permittivity and tan(δ) of the epoxy nanocomposites were measured. The Weibull studies indicate that addition of nanoclay upto 5 wt% enhances the characteristic life of epoxy nanocomposite insulation material. The tracking test results indicate that the tracking time is high with epoxy nanocomposites as compared to pure epoxy. Ageing studies were carried out to understand the surface characteristic variation through contact angle measurement. The hydrophobicity of the insulating material was analysed through contact angle measurement. The diffusion coefficients of the material with different percentage of clay in epoxy nanocomposites were calculated. The exfoliation characteristics in epoxy nanocomposites were analyzed through wide angle X-ray diffraction (WAXD) studies. The thermal behaviour of the epoxy nanocomposites was analyzed by carrying out thermo gravimetric-differential thermal analysis (TG-DTA) studies. Heat deflection temperature of the material was measured to understand the stability of the material for intermittent temperature variation. The dynamic mechanical analysis (DMA) results indicated that storage modulus of the material increases with small amount of clay in epoxy resin. The activation energy of the material was calculated from the DMA results.
Properties of Epoxy Systems with Clay Nanocomposites
Mechanics of Composite Materials, 2003
Different types of montmorillonite clays are often used for the modification of thermoplastic polymers. In the case of epoxy systems, the presence of the clays can complicate the cure process. Therefore, the influence of montmorillonite concentration and the temperature regime on the cure rate and mechanical properties of the composite material obtained is investigated in this paper.
Journal of University of Anbar for Pure Science
In the previous few decades, nanocomposites including epoxy risen-clay nanoparticles systems were proven possibility to have developed properties over original matrices. The environmental conditions, which surround the nanocomposite systems, have a scientific effect on their properties during using them for a long time. Therefore, studying the effect of environmental conditions associated with adding clay nanoparticles on the properties of nanocomposites is important to achieve the requirement of the applications. Nanocomposites are utilized in substructure applications and experience mechanical loads and thermal effects when they are exposed to environmental surrounding conditions which are included electromagnetic ultraviolet (UV) energy, humidity or wetness, water absorbance, and some alkaline solutions. These materials are showed their ability to barrier the environmental surrounding effects. Diffuse the liquids in nanocomposite systems has been established by different approaches (models). The review study involves the research effort performed on nanocomposite (epoxy-clay nanoparticles) under some environmental issues such as moisture or water properties and their diffusion into nanocomposite, exposure to various environments: radiation in the range of UV, temperature, and humidity. The current developments are additionally discussed.
Polymer Engineering and Science, 2011
The effect of the dispersion and intercalation/exfoliation of organoclay on the mechanical properties of epoxy nanocomposites was studied. The epoxy resin was EPON828 and the hardener was Jeffamine D-230, an amine-terminated polyoxypropylene diol. The organoclay Cloisite 30B (montmorillonite treated with a quaternary ammonium intercalant) was used. Nanocomposites were prepared by different mixing devices that can generate different shear forces, such as a mechanical stirrer, a microfluidizer, and a homogenizer. The tensile and compressive properties of the epoxy resin and its epoxy nanocomposites (ENCs) were determined. The effects of nanoclay on the mechanical properties of the EPON828-D230 system were also investigated by dynamic mechanic analysis (DMA). The results indicate that the modulus increases almost linearly with the clay loading and also is improved with the quality of micro-dispersion, although the latter plays a less important role. On the other hand only good dispersion can improve the strength, while poor dispersion results in loss of strength. The strength levels off above 4 wt% organoclay loading. It can be concluded that finer and more uniform dispersion increases the clay surface area available for interaction with the matrix and reduces stress concentration in the large aggregates that initiate the failure under stress. It is also observed that the presence of nanoclay C30B does not significantly affect the T g of the epoxy systems regardless of the level of clay dispersion and clay loading. DMA results also show the positive effect of dispersion and intercalation/exfoliation on the storage modulus of ENCs.
2010
A series of epoxy nanocomposites have been prepared with varying compositions viz., 0, 1, 3, and 5 wt % organically modified montmorillonite (MMT) clay. The effects of MMT nanoclay content on the physico-mechanical and thermal properties of epoxy nanocomposites have been studied. Differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA) have been employed to investigate the thermal characteristics and their mode of thermal degradation. The TGA thermograms of nanocomposites exhibits higher decomposition temperature behaviours compared to the pristine epoxy. It was found that the thermal degradation of all epoxy nanocomposites takes place in one step. All the nanocompsoites were stable upto 221 °C. The thermal degradation kinetic parameters of the composites have been calculated using two mathematical models namely, Coats-Redfern and Broido’s methods. The rheology of polymer was envisaged by DMA is affected on the polymer nanocomposite. Morphological behavioours of ...
Preparation and Properties of Clay-Reinforced Epoxy Nanocomposites
International Journal of Polymer Science, 2013
The clay-reinforced epoxy nanocomposite was prepared by the polymerization method. The effect of clay addition on the mechanical properties of epoxy/clay nanocomposites was studied through tensile, flexural, impact strength, and fracture toughness tests. The morphology and tribology behavior of epoxy/clay nanocomposites were determined by X-ray diffraction (XRD) and wear test, respectively. The wear test was performed to determine the specific abrasion of the nanocomposites. In addition, the water absorption characteristic of the nanocomposites was also investigated in this study. XRD analysis indicated that the exfoliation structure was observed in the epoxy nanocomposites with 3 wt% of clay, while the intercalated structure was shown at 6 wt% of clay. It was found that the addition of clay up to 3 wt% increased the tensile strength, flexural strength, impact strength, and the fracture toughness. On the contrary, the presence of above 3 wt% of clay produced a reverse effect. It cou...
New method for the synthesis of clay/epoxy nanocomposites
Journal of Applied Polymer Science, 2006
A new liquid-liquid method for the synthesis of epoxy nanocomposites was developed. This new method improved the dispersion and exfoliation of the organoclay in the polymer matrix, thus improving the end-use properties. The microstructure and physical properties of the clay/epoxy nanocomposite synthesized by the new method were studied. Rheological tests of the uncured epoxy-organoclay system demonstrated that this method resulted in a great increase in viscosity, much more than the most commonly used direct-mixing method. The Krieger-Dougherty model successfully described the dispersion of the clay layers in the uncured epoxy. In the 5 wt % organoclay nanocomposite, compressive tests on the cured samples showed that there was a 45% increase in the maximum strength, a 10% increase in the yield strength, and a 26% increase in the modulus over the pure epoxy-amine cured system.
Effect of Clay Reinforcement on the Properties of Epoxy based Polymer Matrix Nanocomposites
Organic/inorganic nano-scaled composites comprise one of the most important class of synthetic engineering materials. Their makeup is such that they can be transformed into new materials possessing advantages of both organic materials, such as light-weight, flexibility, and good mould ability, and inorganic materials, such as high strength, heat stability, and chemical resistance. This paper is concerned with the properties of epoxy/layered silicate nanocomposites. The nano-particles used in nanocomposites, due to their extremely high aspect ratios (about 100-15000), and high surface area (in excess of 750-800 m/g) promise to improve structural, mechanical, flame retardant, thermal and barrier properties without substantially increasing the density or reducing the light transmission properties of the base polymer. The main objective of the paper is to review the existing literature to study the effect of clay addition, different curing agents/hardeners and different degassing time periods on the structure and the mechanical properties of nanocomposites.
Polymer Engineering & Science, 2009
The effect of the dispersion and intercalation/exfoliation of organoclay on the mechanical properties of epoxy nanocomposites was studied. The epoxy resin was EPON™ 828 and the hardener was an amine-terminated polyoxypropylene diol, namely Jeffamine ® D-230. The organoclay Cloisite 30B (montmorillonite treated with a quaternary ammonium intercalant) was used. Nanocomposites were prepared by different mixing devices that can generate different shear forces, such as a mechanical stirrer, a microfluidizer, and a homogenizer. The epoxy resin and its nanocomposites were cured at 120°C for 2 hours, with subsequent post cure at 140°C for 2 hours. The tensile and compressive properties of the epoxy resin and its epoxy nanocomposites (ENCs) were determined. The effects of nanoclay on the mechanical properties of the EPON828-D230 system were also investigated by dynamic mechanic analysis (DMA). The results indicate that the modulus increases almost linearly with the clay loading and also is improved with the quality of micro-dispersion, although the latter plays a less important role. On the other hand the strength is very sensitive to the dispersion and only good dispersion can improve the strength, while poor dispersion results in loss of strength. Unlike the modulus, the strength levels off above 4 wt% organoclay loading. It can be concluded that finer and more uniform dispersion increases the clay surface area available for interaction with the matrix and reduces stress concentration in the large aggregates that initiate the failure under stress. It is also observed that the presence of nanoclay C30B does not significantly affect the T g of the epoxy systems regardless of the level of clay dispersion and clay loading. DMA results also show the positive effect of dispersion and intercalation/exfoliation on the storage modulus of ENCs.