The Experts below are selected from a list of 9636 Experts worldwide ranked by ideXlab platform
R. Aleksic - One of the best experts on this subject based on the ideXlab platform.
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Nanosilica/PMMA composites obtained by the modification of silica nanoparticles in a supercritical carbon dioxide–ethanol mixture
Journal of Materials Science, 2009Co-Authors: D. Stojanovic, A. Orlovic, S. Markovic, V. Radmilovic, Petar S. Uskokovic, R. AleksicAbstract:Nanosilica/poly(methyl methacrylate) (PMMA) composites are used to improve the mechanical properties of neat PMMA polymer. In order to obtain superior mechanical properties, it is essential to achieve good bonding between the SiO_2 nanoparticles and the PMMA matrix, which is typically achieved by coating silica nanoparticles with silane coupling agents. In this study, conventional and supercritical coating methods were investigated together with their influence on the mechanical properties of the obtained Nanosilica/PMMA composites. The results indicate advantageous properties of Nanosilica modified in the supercritical phase of carbon dioxide and ethanol in terms of particle size distribution, amount of coated silane, and dispersion in the PMMA matrix. Careful dispersion of the starting silica nanoparticles in ethanol at low temperatures in order to obtain a Nanosilica sol plays an important role in deagglomeration, dispersion, and the coating process. The resulting Nanosilica/PMMA composite containing nanoparticles obtained by supercritical processing of the Nanosilica sol showed an increase in hardness by 44.6% and elastic modulus by 25.7% relative to neat PMMA, as determined using the nanoindentation technique. The dynamic mechanical analysis reveals that addition of nanoparticles as Nanosilica sol and Nanosilica gel enhances composite storage modulus by about 54.3 and 46.5% at 40 °C. At the same temperature, incorporation of modified silica nanoparticles with conventional method leads to an increase of 15.9% for the storage modulus, probably due to a large silica particle size and lower silane content in this sample.
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Nanosilica pmma composites obtained by the modification of silica nanoparticles in a supercritical carbon dioxide ethanol mixture
Journal of Materials Science, 2009Co-Authors: Dusica B Stojanovic, A. Orlovic, S. Markovic, V. Radmilovic, Petar S. Uskokovic, R. AleksicAbstract:Nanosilica/poly(methyl methacrylate) (PMMA) composites are used to improve the mechanical properties of neat PMMA polymer. In order to obtain superior mechanical properties, it is essential to achieve good bonding between the SiO2 nanoparticles and the PMMA matrix, which is typically achieved by coating silica nanoparticles with silane coupling agents. In this study, conventional and supercritical coating methods were investigated together with their influence on the mechanical properties of the obtained Nanosilica/PMMA composites. The results indicate advantageous properties of Nanosilica modified in the supercritical phase of carbon dioxide and ethanol in terms of particle size distribution, amount of coated silane, and dispersion in the PMMA matrix. Careful dispersion of the starting silica nanoparticles in ethanol at low temperatures in order to obtain a Nanosilica sol plays an important role in deagglomeration, dispersion, and the coating process. The resulting Nanosilica/PMMA composite containing nanoparticles obtained by supercritical processing of the Nanosilica sol showed an increase in hardness by 44.6% and elastic modulus by 25.7% relative to neat PMMA, as determined using the nanoindentation technique. The dynamic mechanical analysis reveals that addition of nanoparticles as Nanosilica sol and Nanosilica gel enhances composite storage modulus by about 54.3 and 46.5% at 40 °C. At the same temperature, incorporation of modified silica nanoparticles with conventional method leads to an increase of 15.9% for the storage modulus, probably due to a large silica particle size and lower silane content in this sample.
Pongsak Jittabut - One of the best experts on this subject based on the ideXlab platform.
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effect of Nanosilica on mechanical and thermal properties of cement composites for thermal energy storage materials
Advanced Materials Research, 2015Co-Authors: Pongsak JittabutAbstract:This research article presents the mechanical and thermal properties of cement-based composite for thermal energy storage materials. The effects of Nanosilica particle size and concentration determined by mixing Nanosilica particle size of 50 nm, using Nanosilica were of 1-5 wt%. Thermal properties coefficients were tested using a direct measuring instrument with surface probe (ISOMET2114). The influence of Nanosilica on the performance, such as compressive strength, bulk density, thermal conductivity, volume heat capacity and thermal diffusivity of hardened composite cement pastes were studied for future solar thermal energy materials with better performance. According to the development of thermal storage materials and their application environment requirement in solar thermal power, the specimens were subjected to heat at 350, and 900°C. It were observed that, before heating, the compressive strength is optimized at Nanosilica amount of 4wt% at the age of 28 days. Moreover, after heating at 350 oC and 900°C, the thermal conductivity and volume heat capacity of the cement paste enriched with Nanosilica were significantly lesser than that of the before heating one.
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effect of Nanosilica on mechanical and thermal properties of cement composites for thermal energy storage materials
Energy Procedia, 2015Co-Authors: Pongsak JittabutAbstract:Abstract This research was presented the mechanical and thermal properties of cement-based composite for thermal energy storage materials. The effects of Nanosilica particle size and concentration determined by mixing three Nanosilica particle sizes of 12, 50 and 150 nm, using Nanosilica were of 1-5 wt%. Thermal properties coefficients were tested using a direct measuring instrument with surface probe (ISOMET2114). The influence of Nanosilica on the performance, such as compressive strength, bulk density, thermal conductivity, volume heat capacity and thermal diffusivity of hardened composite cement pastes were studied for future solar thermal energy materials with better performance. According to the development of thermal storage materials and their application environment requirement in solar thermal power, the specimens were subjected to heat at 350 o C and 900 o C. There were observed that, before heating, the compressive strength is optimized at Nanosilica amount of 4wt% with Nanosilica particle size of 50 nm at the age of 28 days. Moreover, after heating at 350 o C and 900 o C, the thermal conductivity and volume heat capacity of the cement paste enriched with Nanosilica were significantly lesser than that of the before heating one.
K Friedrich - One of the best experts on this subject based on the ideXlab platform.
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effect of particle surface treatment on the tribological performance of epoxy based nanocomposites
Wear, 2002Co-Authors: Ming Qiu Zhang, Bernd Wetzel, Shu-li Yu, Min Zhi Rong, K FriedrichAbstract:To overcome the disadvantages generated by the loosened nanoparticle agglomerates dispersed in polymer composites, an irradiation grafting method was applied to modify Nanosilica by covalently bonding polyacrylamide (PAAM) onto the particles. When the grafted Nanosilica was added to epoxy, the curing kinetics of the matrix was accelerated. Moreover, the grafting PAAM can take part in the curing of epoxy so that chemical bonding was established between the nanometer fillers and the matrix. Sliding wear tests of the materials demonstrated that the frictional coefficient and the specific wear rate of Nanosilica/epoxy composites are lower than those of the unfilled epoxy. With a rise in nominal load, both frictional coefficient and wear rate of the composites decrease, suggesting a wear mechanism different from that involved in wearing of epoxy. Grafted Nanosilica reinforced composites have the lowest frictional property and the highest wear resistance of the examined composites. Compared with the cases of microsized silica and untreated Nanosilica, the employment of grafted Nanosilica provided the composites with much higher tribological performance enhancement efficiency.
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improvement of tribological performance of epoxy by the addition of irradiation grafted nano inorganic particles
Macromolecular Materials and Engineering, 2002Co-Authors: Ming Qiu Zhang, Bernd Wetzel, Shu-li Yu, Min Zhi Rong, K FriedrichAbstract:To develop wear resistant nanocomposite coating materials, the authors of the present work treated Nanosilica first by introducing a certain amount of grafting polymers onto the particles in terms of an irradiation technique. Throught irradiation grafting, the nanoparticle agglomerates turn into a nanocomposite microstructure (comprised of the nanoparticles and the grafted, homopolymerized secondary polymer), which in turn built up a strong interfacial interaction with the surrounding epoxy matrix through chain entanglement and chemical bonding during the subsequent mixing and consolidation. The experimental results indicated that the addition of the grafted Nanosilica into epoxy significantly reduced wear rate and frictional coefficient of the matrix at low filler loading. Compared with the cases of microsized silica and untreated nonosilica, the employment of grafted Nanosilica provided composites with much higher tribological performance enhancement efficiency. Unlike the approaches for manufacturing of other types of nanocomposites, the current method is characterized by many advantages, suchs as simple, low cost, easy to be controlled, and broader applicability.
A. Orlovic - One of the best experts on this subject based on the ideXlab platform.
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Nanosilica/PMMA composites obtained by the modification of silica nanoparticles in a supercritical carbon dioxide–ethanol mixture
Journal of Materials Science, 2009Co-Authors: D. Stojanovic, A. Orlovic, S. Markovic, V. Radmilovic, Petar S. Uskokovic, R. AleksicAbstract:Nanosilica/poly(methyl methacrylate) (PMMA) composites are used to improve the mechanical properties of neat PMMA polymer. In order to obtain superior mechanical properties, it is essential to achieve good bonding between the SiO_2 nanoparticles and the PMMA matrix, which is typically achieved by coating silica nanoparticles with silane coupling agents. In this study, conventional and supercritical coating methods were investigated together with their influence on the mechanical properties of the obtained Nanosilica/PMMA composites. The results indicate advantageous properties of Nanosilica modified in the supercritical phase of carbon dioxide and ethanol in terms of particle size distribution, amount of coated silane, and dispersion in the PMMA matrix. Careful dispersion of the starting silica nanoparticles in ethanol at low temperatures in order to obtain a Nanosilica sol plays an important role in deagglomeration, dispersion, and the coating process. The resulting Nanosilica/PMMA composite containing nanoparticles obtained by supercritical processing of the Nanosilica sol showed an increase in hardness by 44.6% and elastic modulus by 25.7% relative to neat PMMA, as determined using the nanoindentation technique. The dynamic mechanical analysis reveals that addition of nanoparticles as Nanosilica sol and Nanosilica gel enhances composite storage modulus by about 54.3 and 46.5% at 40 °C. At the same temperature, incorporation of modified silica nanoparticles with conventional method leads to an increase of 15.9% for the storage modulus, probably due to a large silica particle size and lower silane content in this sample.
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Nanosilica pmma composites obtained by the modification of silica nanoparticles in a supercritical carbon dioxide ethanol mixture
Journal of Materials Science, 2009Co-Authors: Dusica B Stojanovic, A. Orlovic, S. Markovic, V. Radmilovic, Petar S. Uskokovic, R. AleksicAbstract:Nanosilica/poly(methyl methacrylate) (PMMA) composites are used to improve the mechanical properties of neat PMMA polymer. In order to obtain superior mechanical properties, it is essential to achieve good bonding between the SiO2 nanoparticles and the PMMA matrix, which is typically achieved by coating silica nanoparticles with silane coupling agents. In this study, conventional and supercritical coating methods were investigated together with their influence on the mechanical properties of the obtained Nanosilica/PMMA composites. The results indicate advantageous properties of Nanosilica modified in the supercritical phase of carbon dioxide and ethanol in terms of particle size distribution, amount of coated silane, and dispersion in the PMMA matrix. Careful dispersion of the starting silica nanoparticles in ethanol at low temperatures in order to obtain a Nanosilica sol plays an important role in deagglomeration, dispersion, and the coating process. The resulting Nanosilica/PMMA composite containing nanoparticles obtained by supercritical processing of the Nanosilica sol showed an increase in hardness by 44.6% and elastic modulus by 25.7% relative to neat PMMA, as determined using the nanoindentation technique. The dynamic mechanical analysis reveals that addition of nanoparticles as Nanosilica sol and Nanosilica gel enhances composite storage modulus by about 54.3 and 46.5% at 40 °C. At the same temperature, incorporation of modified silica nanoparticles with conventional method leads to an increase of 15.9% for the storage modulus, probably due to a large silica particle size and lower silane content in this sample.
S. Markovic - One of the best experts on this subject based on the ideXlab platform.
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Nanosilica/PMMA composites obtained by the modification of silica nanoparticles in a supercritical carbon dioxide–ethanol mixture
Journal of Materials Science, 2009Co-Authors: D. Stojanovic, A. Orlovic, S. Markovic, V. Radmilovic, Petar S. Uskokovic, R. AleksicAbstract:Nanosilica/poly(methyl methacrylate) (PMMA) composites are used to improve the mechanical properties of neat PMMA polymer. In order to obtain superior mechanical properties, it is essential to achieve good bonding between the SiO_2 nanoparticles and the PMMA matrix, which is typically achieved by coating silica nanoparticles with silane coupling agents. In this study, conventional and supercritical coating methods were investigated together with their influence on the mechanical properties of the obtained Nanosilica/PMMA composites. The results indicate advantageous properties of Nanosilica modified in the supercritical phase of carbon dioxide and ethanol in terms of particle size distribution, amount of coated silane, and dispersion in the PMMA matrix. Careful dispersion of the starting silica nanoparticles in ethanol at low temperatures in order to obtain a Nanosilica sol plays an important role in deagglomeration, dispersion, and the coating process. The resulting Nanosilica/PMMA composite containing nanoparticles obtained by supercritical processing of the Nanosilica sol showed an increase in hardness by 44.6% and elastic modulus by 25.7% relative to neat PMMA, as determined using the nanoindentation technique. The dynamic mechanical analysis reveals that addition of nanoparticles as Nanosilica sol and Nanosilica gel enhances composite storage modulus by about 54.3 and 46.5% at 40 °C. At the same temperature, incorporation of modified silica nanoparticles with conventional method leads to an increase of 15.9% for the storage modulus, probably due to a large silica particle size and lower silane content in this sample.
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Nanosilica pmma composites obtained by the modification of silica nanoparticles in a supercritical carbon dioxide ethanol mixture
Journal of Materials Science, 2009Co-Authors: Dusica B Stojanovic, A. Orlovic, S. Markovic, V. Radmilovic, Petar S. Uskokovic, R. AleksicAbstract:Nanosilica/poly(methyl methacrylate) (PMMA) composites are used to improve the mechanical properties of neat PMMA polymer. In order to obtain superior mechanical properties, it is essential to achieve good bonding between the SiO2 nanoparticles and the PMMA matrix, which is typically achieved by coating silica nanoparticles with silane coupling agents. In this study, conventional and supercritical coating methods were investigated together with their influence on the mechanical properties of the obtained Nanosilica/PMMA composites. The results indicate advantageous properties of Nanosilica modified in the supercritical phase of carbon dioxide and ethanol in terms of particle size distribution, amount of coated silane, and dispersion in the PMMA matrix. Careful dispersion of the starting silica nanoparticles in ethanol at low temperatures in order to obtain a Nanosilica sol plays an important role in deagglomeration, dispersion, and the coating process. The resulting Nanosilica/PMMA composite containing nanoparticles obtained by supercritical processing of the Nanosilica sol showed an increase in hardness by 44.6% and elastic modulus by 25.7% relative to neat PMMA, as determined using the nanoindentation technique. The dynamic mechanical analysis reveals that addition of nanoparticles as Nanosilica sol and Nanosilica gel enhances composite storage modulus by about 54.3 and 46.5% at 40 °C. At the same temperature, incorporation of modified silica nanoparticles with conventional method leads to an increase of 15.9% for the storage modulus, probably due to a large silica particle size and lower silane content in this sample.
