Coalescence and Phase Separation During Spinodal Decomposition of Solvent Mixtures Far From Critical Point

远离临界点的溶剂混合物旋节线分解过程中的聚结和相分离

• 批准号: 0123445
• 负责人: Reuel Shinnar
• 金额: --
• 依托单位: CUNY City College
• 依托单位国家: 美国
• 项目类别: Continuing grant
• 财政年份: 2001
• 资助国家: 美国
• 起止时间: 2001-12-15 至 2005-05-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=0123445&HistoricalAwards=false
• 关键词: Coalescence; Phase; Separation; During; Spinodal

AbstractCTS-0123445Shinnar, ReuelCUNY City CollegeThe PI's main achievement so far has been to show, both experimentally and theoretically, that phase separation of low-viscosity liquid mixture is driven by the convection induced by a non-equilibrium force due to gradients of chemical potential and that this force can act over distances of a few centimeters. While the investigation has produced novel and unexpected results, much work is required to achieve the ultimate goal and model the flow of liquid mixtures during phase transition in the presence of surface-active compounds. As has been stressed, the results so far have opened a new and till now unknown area of research which they do not expect to exhaust within the time frame of the proposed investigation. What the PI's would like to do, instead, is to focus on the most needed areas, to enhance the understanding of the dynamics of phase separation and increase the applicability of its unique properties to the solution of practical problems. In fact, they expect that coalescence can be eventually retarded increasing the amount of surfactants and of thickeners, thereby increasing the viscosity of the mixtures, or when quenching the mixture into its metastable region. Therefore, they intend to determine the thresholds of the surfactant concentration and of the mixture viscosity and composition beyond which surfactants start to slow down significantly the separation process, just as they do in the absence of phase transition. In addition, the PI's want to study how mixing, which is necessary to rapidly cool the system, can counteract the effect of phase transition, causing the formation of stable emulsions.As in the past, the experimental work will be accompanied by modeling and simulation, in such a way that these two activities will interact and compliment with each other. The results should not only lead to a better understanding of spinodal decomposition and nucleation, but will also be of great value to any industrial applications of this approach to phase separation. In particular, the PI's want to focus on the following areas of research, to be addressed both experimentally and numerically.

到目前为止，PI的主要成就是从实验和理论上证明了低粘度液体混合物的相分离是由化学势梯度引起的非平衡力引起的对流驱动的，这种力可以作用在几厘米的距离内。虽然这项研究取得了新的和意想不到的结果，但要实现最终目标并模拟存在表面活性化合物的相变过程中的液体混合物的流动，还需要做大量的工作。正如所强调的那样，到目前为止，调查结果开启了一个新的、迄今未知的研究领域，他们预计不会在拟议调查的时间范围内耗尽这一领域。相反，PI想要做的是专注于最需要的领域，加强对相分离动力学的理解，并增加其独特性质在解决实际问题中的适用性。事实上，他们预计，增加表面活性剂和增稠剂的数量，从而增加混合物的粘度，或者在混合物淬火到其亚稳态区域时，最终可以延缓聚结。因此，他们打算确定表面活性剂浓度以及混合物粘度和组成的阈值，超过这些阈值，表面活性剂开始显著减缓分离过程，就像它们在没有相变的情况下所做的那样。此外，PI希望研究快速冷却系统所必需的混合如何抵消相变的影响，从而形成稳定的乳状液。与过去一样，实验工作将伴随着建模和模拟，以使这两种活动相互作用和互补。研究结果不仅有助于更好地理解调幅分解和成核过程，而且对于这种相分离方法的工业应用也具有重要的价值。特别是，PI希望专注于以下领域的研究，将从实验和数字两个方面加以解决。