我們主要研究了多孔體系在乾燥過程中的兩個現象: 一是裂縫行為，二是污染相在孔隙間的擴散特點、機理以及收集污染相、解決污染問题的方法。 / 在本文的第一部分中，我們用共聚焦顯微鏡觀察到了膠體懸浮體系在溶劑揮發時產生裂縫。我們尋找到一個可令裂縫完全消除的辦法：加入乳液到膠體體系後，裂縫的數量減少；當乳液達到一定濃度時，裂縫完全被消除。同時我們也發現加入乳液帶給體系的另一效應：空氣進入體系的速度也發生改變，從而實現了乾燥速度可控。通過用流變儀研究樣品的基本力學性質，我們找出了裂縫數量減少的根本原因。我們的方法可同時有效地控制裂縫數量和體系乾燥速度，因而在許多涉及到多孔體系乾燥或裂縫的工業過程中有潛在的應用。 / 在本文的第二部分中，我們受到石油洩漏污染海灘的啟發，研究了污染相在多孔體系里的擴散特點及機理，並在此基礎上設計了有效的處理方案。我們搭建了一個小尺度的系統來模擬石油滲入沙灘的過程，記錄了隨著海水沖洗次數的增加污染相在多孔體系里的分佈變化。我們發現不論是親水還是疏水的多孔體系，在幾次海水沖刷週期后，污染相都有了明顯的擴散；但是對於不同的體系，污染相呈現出不同的分佈和擴散特點。通過分析小孔尺度上體系內部的壓強分佈，我們很好地解釋了造成這種不同的基本原因。最後我們尋找到兩種可令污染相集中的方法，這對解決實際污染問题有一定的幫助。 / We study two interesting phenomena occurred during the evaporation of solvent in porous medium: first, the cracking behavior; and second, the expanding mechanism and the collecting methods of the non-evaporative phase. / In the first part of this thesis, we visualize the cracking behavior of colloidal suspensions during drying by a confocal microscope. We develop an effective method which can completely eliminate cracking during drying: by adding emulsion droplets into colloidal suspensions, we can systematically decrease the amount of cracking, and eliminate it completely above a critical droplet concentration. We also find another effect that the emulsion droplets can bring: it varies the speed of air invasion and provides a powerful method to adjust drying rate. Besides, we investigate the samples’ fundamental mechanical properties with a rheometer and clarify the underlying physical mechanism for the decreasing of crack amounts. With the effective control over cracking and drying rate, our study may find important applications in many drying and cracking related industrial processes. / In the second part of the thesis, we conduct a study on the expanding mechanism and collecting methods of the non-evaporative phase in porous medium, which is inspired by a practical pollution problem that occurs when oil spills to the sandy beach. We build a system in a smaller scale to mimic the practical pollution and investigate the distribution change of the polluting phase as the flushing cycle increases. We find an obvious expansion of the polluting phase after several flushing cycles in both hydrophilic and hydrophobic porous media, but with different distributions and expanding behaviors. We explained this difference by analyzing the pressure distribution in the system at the pore level. Finally, we develop two methods to concentrate the polluting phase in some particular regions, which is beneficial to collect and solve the practical pollution problem. / Detailed summary in vernacular field only. / Detailed summary in vernacular field only. / Detailed summary in vernacular field only. / Jin, Qiu = Duo kong ti xi lie feng he you ru qin de yan jiu / Jin Qiu. / Thesis (Ph.D.) Chinese University of Hong Kong, 2014. / Includes bibliographical references (leaves 62-67). / Abstracts also in Chinese.
| Identifer | oai:union.ndltd.org:cuhk.edu.hk/oai:cuhk-dr:cuhk_1077719 |
| Date | January 2014 |
| Contributors | Jin, Qiu (author.), Ng, Hang Leung Dickon (thesis advisor.), Chinese University of Hong Kong Graduate School. Division of Materials Science and Engineering, (degree granting institution.) |
| Source Sets | The Chinese University of Hong Kong |
| Language | English, Chinese |
| Detected Language | English |
| Type | Text, bibliography, text |
| Format | electronic resource, electronic resource, remote, 1 online resource (xvii, 67 leaves) : illustrations (some color), computer, online resource |
| Rights | Use of this resource is governed by the terms and conditions of the Creative Commons “Attribution-NonCommercial-NoDerivatives 4.0 International” License (http://creativecommons.org/licenses/by-nc-nd/4.0/) |
Page generated in 0.0022 seconds