Phase behaviour in slits - When tight cracks stay wet
Phase behaviour in slits - When tight cracks stay wet
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DOI：
10.1016/s0927-7757(96)03781-8
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发表时间：
1997-05-15
影响因子：
5.2
通讯作者：
Christenson, HK
中科院分区：
文献类型：
--
作者：
Christenson, HK
用一种简化的表面力装置可以方便地研究局限于单缝孔隙中的流体的相行为。这样的研究是可能的，因为与背面镀银云母表面的多光束干涉测量允许中间介质的折射率被确定。可以测量（有效的）单个表面上的吸附等温线，并研究在小分离时两个表面之间发生的毛细冷凝转变作为相对蒸汽压的函数。结果表明，环己烷在云母上的吸附等温线形状与椭偏仪测定的等温线形状定性一致。发现叔丁醇中的毛细缩合转变可以很好地描述为在范德华力作用下吸附膜的聚并。对于较薄的吸附膜，对于叔丁醇和环己烷，过渡发生在大于预期狭缝宽度的地方。在低于体熔点的温度下，由于表面能的限制，毛细冷凝物保持液态。叔丁醇和新戊醇凝析液的最大尺寸与冰点以下温度成反比，该关系提供了固液界面能的信息。
The phase behaviour of fluids confined to a single-slit pore can be conveniently studied with a simplified surface force apparatus. Such investigations are possible because multiple-beam interferometry with back-silvered mica surfaces allows the refractive index of the intervening medium to be determined. Adsorption isotherms at (effectively) single surfaces can be measured, and the capillary condensation transition occurring between two surfaces at small separations studied as a function of the relative vapour pressure. The shape of the adsorption isotherm of cyclohexane on mica is shown to be in qualitative agreement with that determined by ellipsometry. The capillary condensation transition in tert-butanol is found to be well described by the coalescence of adsorbed films due to van der Waals forces for films thicker than about 4 nm. For thinner adsorbed films the transition occurs for larger than expected slit widths, for both tert-butanol and cyclohexane. At temperatures below the bulk melting point capillary condensates remain liquid because of surface energy constraints. The maximum size of liquid condensates of tert-butanol and neopentanol is inversely proportional to the temperature below the freezing point, and the relationship gives information on solid-liquid interfacial energies.