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Imbibition and structure of silica nanoporous media characterized by neutron imaging.
Journal of Colloid and Interface Science ( IF 9.4 ) Pub Date : 2020-01-17 , DOI: 10.1016/j.jcis.2020.01.052
Marguerite Léang 1 , Frédéric Ott 2 , Frédérique Giorgiutti-Dauphiné 3 , Ludovic Pauchard 3 , Lay-Theng Lee 2
Affiliation  

HYPOTHESIS Colloidal silica dispersions dried under controlled conditions form solid gels that display mechanical properties similar to those observed in several practical processes. An understanding of their structural characteristics and liquid flow properties can therefore help establish these gels as an alternative family of model materials to study practical porous systems. EXPERIMENTS Neutron radiography is a non-destructive technique well-adapted to study hydrogen-rich domains in porous materials due to the high attenuation power of hydrogen. We apply this technique to study gels prepared from silica nanoparticles of radii 5-40 nm. FINDINGS The water content in the gels have been quantified and different types of porosities have been determined: total porosity, effective porosity that contributes to liquid flow, and residual porosity that contains bound residual water. This residual water increases with decrease in particle size and constitutes an important fraction of the gel. The dynamics of water imbibition follows a √t law, from which the effective pore size and permeability are evaluated. We highlight the role of particle size on water retention, on particle organization and its impact on mechanical resistance. Quantitative analysis of the propagating liquid front shows front broadening that suggests elongated pores with reduced correlated liquid menisci.

中文翻译:

以中子成像为特征的二氧化硅纳米多孔介质的吸收和结构。

假设在控制条件下干燥的胶态二氧化硅分散体会形成固体凝胶,其机械性能与几种实际工艺中观察到的相似。因此,了解它们的结构特征和液体流动特性可以帮助将这些凝胶确立为研究实际多孔系统的另一类模型材料。实验中子射线照相技术是一种非破坏性技术,非常适合研究多孔材料中的富氢畴,这是因为氢的衰减能力很高。我们应用这项技术来研究由半径为5-40 nm的二氧化硅纳米粒子制备的凝胶。结果凝胶中的水含量已经量化,并且确定了不同类型的孔隙率:总孔隙率,有助于液体流动的有效孔隙率,残留孔隙度包含结合的残留水。该残留水随着粒度的减小而增加,并且构成凝胶的重要部分。吸水动力学遵循√t律,从中可以评估有效孔径和渗透率。我们重点介绍了粒径对保水率,颗粒组织及其对机械阻力的影响。传播的液体前沿的定量分析表明,前沿增宽表明孔隙延长,相关的液体弯液面减少。我们重点介绍了粒径对保水率,颗粒组织及其对机械阻力的影响。传播的液体前沿的定量分析显示,前沿拓宽表明孔隙延长,相关的液体弯月面减少。我们重点介绍了粒径对保水率,颗粒组织及其对机械阻力的影响。传播的液体前沿的定量分析表明,前沿增宽表明孔隙延长,相关的液体弯液面减少。
更新日期:2020-01-17
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