Low Pressure Hysteresis in Materials with Narrow Slit Pores
Low Pressure Hysteresis in Materials with Narrow Slit Pores
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DOI：
10.3390/colloids2040062
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发表时间：
2018-11
影响因子：
2.4
通讯作者：
P. Schiller;M. Wahab;T. Bier;H. Mögel
中科院分区：
文献类型：
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作者：
P. Schiller;M. Wahab;T. Bier;H. Mögel
即使在较低的相对蒸汽压下，依赖湿度的缝隙孔的关闭和重新打开也会在吸附图中产生滞后环。缝隙壁面的粘附力支撑着孔洞的闭合。在狭缝中吸附滞后的宏观模型中，当接触缝隙壁彼此分离时，粘着能跳跃有限的值。我们考虑了一种更真实的粘附力模型，通过引入一种平滑变化的粘附力，该粘附力取决于缝隙壁之间的距离。在较低的蒸气压下，缝隙壁之间的引力范围对磁滞回线的形状有显著的影响。大的相互作用范围避免了孔道闭合所需的极小的相对蒸汽压，这是低压滞后的前提条件。我们的扩展模型允许我们描述不连续，它可以出现在硬化水泥浆体的膨胀/收缩图的解吸分支中。
Humidity-dependent closing and reopening slit pores can produce hysteresis loops in sorption diagrams even at low relative vapor pressure. Pore closing is supported by adhesion of the slit wall surfaces. In a macroscopic model for sorption hysteresis in narrow slits, the adhesion energy jumps by a finite value when touching slit walls are separated from each other. We consider a more realistic adhesion model by introducing a smoothly-varying adhesion force, which depends on the distance between the slit walls. The range of the attraction between the slit walls is found to have a pronounced influence on the shape of hysteresis loops at low vapor pressure. A large interaction range avoids an extraordinarily small relative vapor pressure necessary for pore closing, which is a precondition for low pressure hysteresis. Our extended model allows us to describe a discontinuity, which can appear in the desorption branch of swelling/shrinkage diagrams for hardened cement paste.