Vertical water distribution during the drying of polymer films cast from aqueous emulsions
Vertical water distribution during the drying of polymer films cast from aqueous emulsions
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由水乳液浇铸的聚合物薄膜干燥过程中的垂直水分布
DOI：
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发表时间：
2002
期刊：
影响因子：
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通讯作者：
J. Keddie
中科院分区：
文献类型：
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作者：
J. Gorce;D. Bovey;P. J. McDonald;P. Palasz;D. Taylor;J. Keddie
翻译后摘要：我们提出了一个系统的研究水分布的垂直均匀性在干燥过程中的水性胶体膜，测试的预测Peclet数Pe定义为这个系统。Pe表示水蒸发和布朗扩散在确定垂直方向（即垂直于基底）的浓度分布方面的相对贡献。当Pe < 1时，通过磁共振分布发现由醇酸乳液浇铸的膜中的水浓度随深度均匀，这与预期一致。当Pe > 1时，水浓度的梯度发展，在与空气的界面附近具有较少的水。水分布揭示醇酸树脂颗粒在紧密堆积接触时不会立即聚结。在稍后的时间，形成浓缩的表面层，但是颗粒在该层中没有聚结以形成连续的“表皮”，而是结构可能是双液泡沫的结构。
Abstract:We present a systematic study of the vertical uniformity of water distribution during the drying of waterborne colloidal films, testing the predictions of a Peclet number Pe defined for this system. Pe indicates the relative contributions of water evaporation and Brownian diffusion in determining the concentration profile in the vertical direction (i.e. normal to the substrate). When Pe < 1, the water concentration in films cast from an alkyd emulsion is found via magnetic-resonance profiling to be uniform with depth, which is consistent with expectations. When Pe > 1, a gradient in the water concentration develops, with less water near the interface with air. The water profiles reveal that the alkyd particles do not coalesce immediately upon contact in close-packing. At later times, a concentrated surface layer develops, but particles are not coalesced in this layer to form a continuous “skin”, but rather the structure is likely to be that of a biliquid foam.