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首页> 外文会议>ASME(American Society of Mechanical Engineers)/JSME Pressure Vessels and Piping Conference: Computational Technologies for Fluid/Thermal/Structural/Chemical Systems with Industrial Applications v.1; 20040725-20040729; San Diego,CA; US >INVESTIGATION OF THE WATER FLOW INTO A MESOPOROUS MATRIX FROM HYDROPHOBIZED SILICA GEL
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INVESTIGATION OF THE WATER FLOW INTO A MESOPOROUS MATRIX FROM HYDROPHOBIZED SILICA GEL

机译：研究水从硅化凝胶中渗入到中孔基质中

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In this work a generalized hydrodynamic theory for the water flow into a mesoporous matrix from hydrophobized silica gel is suggested. Although we examine a fluid dynamics problem, i.e., the motion of the water-gas-solid contact line, motivation for such research derives from the investigation of a novel principle of mechanical energy dissipation, called colloidal damper. Similar to hydraulic damper, this absorber has a cylinder-piston structure, but oil is replaced by a colloid consisted of a mesoporous matrix and a lyophobic liquid. Here, the mesoporous matrix is from silica gel modified by linear chains of alkyldimethylchlorosilanes and water is the associated lyophobic liquid. Mainly, the colloidal damper energy loss can be explained by the dynamic contact angle hysteresis in advancing (liquid displaces gas) and receding (gas displaces liquid); such hysteresis occurs due to the geometrical and chemical heterogeneities of the solid surface. Measuring technique of the hysteresis loop is described. From experimental data one calculates the dissipated energy, damper efficiency and the damping coefficient versus the length of the grafted molecule on the silica gel surface. Experimental results are justified by the flow analysis. Generalized hydrodynamic theory means here that the basic structure of Navier-Stokes equations is kept, but in order to include the relation between macroscopic flow and molecular interactions, slip is allowed on the solid wall. Nano-pillar architecture of the silica gel hydrophobic coating is described. During adsorption, water penetrates the pore space by maintaining contact with the top of the coating molecules (region of -CH_3 groups); after that, water is forced into and partially or totally fills the space between molecules (region of -CH_2 groups); in such circumstances, at the release of the external pressure, desorption occurs. Mechanism of energy dissipation is discussed. Results obtained are useful for the appropriate design of the hydrophobic coating of a mesoporous matrix which is destined to colloidal damper use.
机译：在这项工作中，提出了一种通用的水动力理论，即水从疏水化硅胶流入中孔基质的过程。尽管我们研究了流体动力学问题，即水-气-固接触线的运动，但这种研究的动机来自对机械能耗散的一种新型原理-胶体阻尼器-的研究。类似于液压阻尼器，该吸收器具有圆柱活塞结构，但是油被由介孔基质和疏液性液体组成的胶体代替。在此，中孔基质是由烷基二甲基氯硅烷的线性链改性的硅胶，水是相关的疏液液体。胶体阻尼器的能量损失可以用前进（液体置换气体）和后退（气体置换液体）时的动态接触角滞后来解释。这种滞后是由于固体表面的几何和化学异质性而发生的。描述了磁滞回线的测量技术。根据实验数据，可以计算出耗散的能量，阻尼效率和阻尼系数与硅胶表面接枝分子长度的关系。流动分析证明了实验结果的合理性。广义流体力学理论在这里意味着保留了Navier-Stokes方程的基本结构，但是为了包括宏观流动和分子相互作用之间的关系，在固体壁上允许滑动。描述了硅胶疏水涂层的纳米柱结构。在吸附过程中，水通过保持与涂层分子顶部（-CH_3基团的区域）接触而渗透到孔隙空间中。之后，水被迫进入并部分或全部填充分子之间的空间（-CH_2基团区域）；在这种情况下，在释放外部压力时，发生解吸。讨论了能量耗散的机理。获得的结果对于介孔基质的疏水涂层的适当设计是有用的，该介孔基质预定用于胶体阻尼器。

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