Papers by Keyword: Nano-SiO2

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Authors: Zhi Qin Zhao, Ren Juan Sun, Gong Feng Xin, Shan Shan Wei, Da Wei Huang
Abstract: In this paper, the current situation of nanomaterials used in concrete were introduced, mechanism of nanomaterilas was reviewed. Recent application of nanomaterilas in special concrete such as air purified concrete, eco-concrete, high tenacity concrete were present.
Authors: Zhuo Chen, Jun Guo, Hao Li Qin, Hui Xie, Ke Jia Liu, Wei Zhao, Ji Ping Liu
Abstract: Polyimide/nano-SiO2 (PI/SiO2) composites with different contents of SiO2 were prepared by in situ polymerization. The transmittance, solubility, thermal property, flame retardant properties and mechanics properties of PI/nano-SiO2 composites were investigated. The results showed that with the increased addition of SiO2 content, the transmittance of PI/SiO2 compositions reduced; tensile strength changed with the amount of nanometer powder, when the addition content was 10 wt%, it achieve the maximum value. Thermal resistance of the composite was improved obviously while with the amount of nanometer powder increased, volume resistivity coefficient of volume resistance would have decreased.
Authors: Jian Hua Du, Xiao Hui Zheng, Xiao Ying Zhu
Abstract: Copper based composite powders with nano-SiO2 were prepared by mechanical milling technology. The effects of milling time on morphology and component of the composite particles were characterized by scanning electron microscopy (SEM) and energy disperse X-ray spectroscopy (EDS), respectively. Results showed that dendrite composite particles change to the flaky, and then to spherical ones with the milling time increasing. The n-SiO2 particles disperse more homogeneously in the composite particles with the milling time increasing.
Authors: Xiang Gao, Qing Hua Li, Shi Lang Xu
Abstract: High performance nano-binder cementitious composites (HPNCC) are ultra-ductile fiber reinforced cementitious composites with special matrix. The compressive strength and flexural properties of HPNCC containing nano-SiO2 particles were investigated at age of 3d, 7d, 14d and 28d. According to the results, HPNCC exhibited excellent mechanical properties in the test. The compressive strength, flexural strength and first crack strain of HPNCC were all increased obviously at early age except the ultimate strain. In the flexural test, both crack extension width and the number of fine cracks decrease along with the curing age. However, the average crack spacing has no remarkable changes. Nano-SiO2 particles in HPNCC acted as ultra-fine fillers and catalyzers to strengthen the interfacial bond between the matrix and PVA fiber which improved the mechanical properties and would make HPNCC be widely used in the engineering.
Authors: Yan Sheng Yang, Wei Yu Fan, Zhe Wang, Qin Qin Zhang, Guo Zhi Nan
Abstract: The effects of nanoSiO2 content on the Engler viscosity and storage stability of asphalt emulsion as well as the performances of asphalt emulsion residue were investigated. The results indicate that the Engler viscosity increases and storage stability of the emulsion is improved as the nanoSiO2 dosage increases from 0 wt % to 1.2 wt %. With the nanoSiO2 content increasing, it represents a reduction in the ductility and penetration of the asphalt emulsions residue. However, compositions of saturate, aromatic, resin and asphaltene (SARA) of the asphalt emulsions residue change slightly. The viscosity of the asphalt emulsions residue increases as the nanoSiO2 content increases from 0 wt % to 1.2 wt % at temperatures from 70 °C to 120 °C and changes slightly when the temperature is higher than 120 °C.
Authors: Hai Jun Fan, Ming Liang Luo, Zi Long Jia, Hou Tai Sun
Abstract: The effects of nano-SiO2 on the rheology of viscoelastic solutions formed by the bio- degradable surfactant fatty acid methyl ester sulfonate (MES) were studied. The process of MES micelles transforming from sphere or rod to wormlike was investigated with the increase in NaCl concentration by rheological measurements. The increase in η0 on the introduction of SiO2 was explained by considering the increasingly entangled wormlike micelles that were formed due to the screening of the electrostatic interactions. The results of rheological measurements show that the system of MES /NaCl can transform into wormlike micelles. MES micelle solutions without SiO2 are linear viscoelastic fluids in accord with a Maxwell model having a single relaxation time. But there is a process with some distributions of the relaxation time for MES micelle solution with SiO2.
Authors: D. Stojanović, P. S. Uskoković, I. Balać, V.J. Radojević, R. Aleksić
Abstract: Composites with nano-SiO2 particles and high density polyethylene (HDPE) matrix were produced by hot pressing with various particle contents and particle surface treatment using commercially available silane coupling agents: γ-methacryloxypropyltrimethoxy silane and γ- glycidyloxypropyltrimethoxysilane. The influence of the particle treatment on the mechanical properties of composites was determined by compression and indentation tests. Additionally, numerical analysis was performed in order to calculate Young’s modulus and stress concentrations for various particle contents in order to provide reference data by simulating micro- and macro particle composites with perfect bonding to the matrix.
Authors: Ji Yan Liu, Shi Ning Ma, Ji Qiu, Xiang Bo Suo
Abstract: Good dispersing stability is required for nano-SiO2 which, however, tends easily to conglomerate, to be widely applied as an important functional material of high toughness, high resistance to corrosion and good high-temperature performance. Through ultrasonic treatment, the suspension of SiO2 nano-powder in water was prepared utilizing sodium dodecylbenzenesulfonate (SDBS) as the dispersant. The effect of SDBS content and ultrasonic treatment time on the suspension stability was investigated by way of testing the particle size of SiO2 nano-powder, the Zeta potential and transmittance of the suspension. The results show that with increasing SDBS content, the particle size of SiO2 nano- powder decreases and then increases, which is similar to the case of increasing the ultrasonic treatment time. With optimum SDBS content, the suspension of SiO2 nano-powder possesses a good dispersing stability due to the existence of electrostatic and steric effects resulting from the particular structure of SDBS. The optimum dispersing condition is SDBS of 1.6 wt% with the ultrasonic time of 18 min.
Authors: Breno D. Queiroz, Vitor L.P. Janzantti, José Donato Ambrósio
Abstract: Nanocomposites of polyamide-6 with nanoSiO2 surface modified by 3-aminopropyltrimethoxysilane (3-APTMS) were prepared by melt blending in torque rheometer. Chemical modification of nanoparticles surface with 3-APTMS were observed by FTIR. Prior to nanocomposites processing, neat polyamide-6 (PA-6) was processed in a torque rheometer with varying processing parameters: polymer residence time in the chamber, rollers rotational speed, and polymer filling volume in the chamber. Two levels for each parameter were fixed. The influence of these parameters on degradation of PA-6 was determined by dilute solution viscosity and capillary rheometry. Results indicate that the best condition was achieved with the higher polymer residence time in the chamber, the higher rollers rotational speed, and the higher polymer filling volume in the chamber. With this information, PA-6 pellets were mixed with nanosilica particles unmodified and surface-capped by 3-APTMS via melt blending in torque rheometer, obtaining PA-6 composites with 1 wt.% of nanofillers. Mechanical and thermal properties of nanocomposites were evaluated by means of tensile test and differential scanning calorimetry (DSC).
Authors: Bing Tao Wang, Ping Zhang, Yan Zhang, Zheng Ping Fang
Abstract: Biodegradable aliphatic-aromatic copolyesters nanocomposites were designed and prepared via direct melt polycondensation of terephthalic acid (TPA), 1,4-butanediol (BDO), poly(L-lactic acid) oligomer (OLLA) and nano-SiO2 or nanostructured cage POSS reagent (POSS). The morphologies and dispersions of two nanofillers and their comparative effects on the mechanical properties of the nanocomposites were investigated. TEM characterizations confirmed that both nano-SiO2 and POSS took good dispersions in the copolyesters matrix. Due to the presence of flexible PEG tails and inorganic-organic nanocaged hybrid structures, POSS showed rather better dispersions and formed more strong interactions with the matrix than nano-SiO2. The experimental results indicated that incorporation of nano-SiO2 or POSS-PEG was a simple and rather effective way to greatly enhance the mechanical and thermal properties of the nanocomposites. Comparative studies of the effects between nano-SiO2 and POSS demonstrated that the introduction of POSS-PEG not only remarkably improved the tensile strength from 6.4 MPa to 11.2 MPa and Young’s modulus from 9.6 MPa to 70.7 MPa, but also dramatically increased the elongation at break from 190 % to 350%.
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