Relationship Between Pore Structure and Sorption-Induced Deformation in Hierarchical Silica-Based Monoliths
Relationship Between Pore Structure and Sorption-Induced Deformation in Hierarchical Silica-Based Monoliths
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DOI：
10.1515/zpch-2014-0542
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发表时间：
2015-08
期刊：
影响因子：
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通讯作者：
C. Balzer;Roland Morak;M. Erko;Christos Triantafillidis;N. Hüsing;G. Reichenauer;O. Paris
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文献类型：
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作者：
C. Balzer;Roland Morak;M. Erko;Christos Triantafillidis;N. Hüsing;G. Reichenauer;O. Paris
摘要采用原位X射线衍射和原位小角X射线散射（SAXS）技术，研究了正戊烷脱附过程中吸附诱导的变形。所研究的样品是具有分级孔结构的基于二氧化硅的整料，其包含支柱的大孔网络，每个支柱含有在2D六边形晶格上有序的明确限定的圆柱形中孔。原位应变测量和原位SAXS测量显示了类似形状的应变等温线，这与最近的理论预测定性吻合。从液体填充的中孔的相对压力范围确定1.5GPa的孔负载模量。然而，单层和多层地层的相对压力区域揭示了两种独立方法之间的差异。特别是，在饱和压力下的净应变是相当大的原位电阻率测量。我们将这一观察归因于两种方法对分层固体框架中各向异性变形的不同敏感性。虽然原位SAXS测量中孔晶格应变，因此仅对支柱的径向变形敏感，但应变测量法测量各向同性宏观样品的线性变形，对整个网络的体积应变敏感。
Abstract Experimental results on sorption-induced deformation during n-pentane desorption were obtained by in-situ dilatometry and in-situ small angle X-ray scattering (SAXS). The sample investigated was a silica-based monolith with hierarchical pore structure comprising a macroporous network of struts, each strut containing well-defined cylindrical mesopores ordered on a 2D hexagonal lattice. In-situ dilatometry and in-situ SAXS measurements revealed strain isotherms of similar shape, which are qualitatively in good agreement with recent theoretical predictions. From the relative pressure range of the liquid filled mesopores a pore load modulus of 1.5 GPa is determined. The relative pressure region of mono- and multilayer formation, however, reveals differences between the two independent methods. In particular, the net strain at saturation pressure is considerably larger for in-situ dilatometry. We attribute this observation to the different sensitivity of the two methods to anisotropic deformation in the hierarchical solid framework. While in-situ SAXS measures the mesopore lattice strain and is therefore exclusively sensitive to radial deformation of the struts, dilatometry measures the linear deformation of the isotropic macroscopic sample, being sensitive to the volumetric strain of the whole network.