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455 results on '"Wei, Jiangxiong"'

34. Preparation of Nano - SiO2 Modified Waterborne Polyurethane Coatings and Its Influence on the Anti - Permeability of Concrete

Author

LONG Qing, HUANG Jinzhen, WEI Jiangxiong, YU Qijun, HU Jie

Subjects
modified nano-sio2, silane coupling agent, waterborne polyurethane coating, concrete, permeability resistance, Materials of engineering and construction. Mechanics of materials, TA401-492, Technology
Abstract

For improving the anti-permeability of waterborne polyurethane coatings to concrete,the silane coupling agent was applied to modify the surface of nano-SiO2 to reduce the reunion degree of nanoparticles,and then the modified nano-SiO2 with better dispersibility was added into the waterborne polyurethane coatings.The modification effect of silane coupling agent on nano-SiO2 was analyzed by thermal analysis (TG),infrared spectroscopy (FT-IR) and dynamic light scattering (DLS),and the effect of nano-SiO2 on the morphology and composition of waterborne polyurethane coatings was also expounded.Furthermore,the influence of nano-SiO2 modified waterborne polyurethane coatings on the anti-permeability of concrete was analyzed.Results showed that the nano-SiO2 modified by silane coupling agent possessed less-OH on the surface and a lower reunion degree.Comparing with the concrete specimens painted with the polyurethane coatings containing no SiO2 or unmodified nano-SiO2,the concrete specimen painted with polyurethane coating containing modified nano-SiO2 had stronger adhesion between the coating and the concrete.The capillary water absorption per unit area of the specimen and the penetration depth of chloride ions were reduced,and the permeability resistance of the concrete was improved.

Published
2022
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43. Synthesis and characterization of double‐shell structure hollow SiO2 nanospheres.

Author

Li, Fangxian, Wang, Yasong, Ma, Liang, Li, Bin, Wei, Jiangxiong, Yu, Qijun, and Jiang, Jun

Subjects
THERMAL conductivity, POROSITY, ACRYLIC coatings, THERMAL properties, ETHYL silicate
Abstract

The objective of this study is to synthesize hollow SiO2 nanospheres (HSNs), and to investigate the effect of varying divinylbenzene (DVB) amounts during synthesis on their morphology and pore structure. Additionally, it seeks to characterize the thermal conductivity of the synthesized HSNs and evaluate the impact of their incorporation on the thermal insulation properties of acrylic coatings. Single‐shell HSNs were synthesized using the Stöber method, which involved hydrolysis‐polycondensation of tetraethyl orthosilicate. The double‐shell HSNs were prepared using a stepwise wrapping synthesis method, with single‐shell HSNs as the core matrix and an appropriate amount of crosslinking agent added. The addition of DVB resulted in different morphologies, shell spacings, and specific surface areas for the double‐shell HSNs. The thermal conductivity of the double‐shell HSNs decreased significantly to as low as 0.0252 W·m1·K−1 with an increase in shell spacing. The shell spacing of double‐shell HSNs had doubled, resulting in a reduction of its thermal conductivity by approximately 18%. When the double‐shell HSN content reached 8%, the thermal conductivity decreased by 85% compared to that of the original acrylate coating. These results indicate that double‐shell HSNs can substantially decrease the thermal conductivity of the matrix material for thermal insulation applications. [ABSTRACT FROM AUTHOR]

Published
2024
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