Next Article in Journal
Substituted Caffeic and Ferulic Acid Phenethyl Esters: Synthesis, Leukotrienes Biosynthesis Inhibition, and Cytotoxic Activity
Next Article in Special Issue
Solvent Supercritical Fluid Technologies to Extract Bioactive Compounds from Natural Sources: A Review
Previous Article in Journal
Protective Effect of Quercetin against Oxidative Stress-Induced Cytotoxicity in Rat Pheochromocytoma (PC-12) Cells
Previous Article in Special Issue
Pattern Evolution during Double Liquid-Vapor Phase Transitions under Weightlessness
Article Menu
Issue 7 (July) cover image

Export Article

Open AccessArticle
Molecules 2017, 22(7), 1125;

Measuring the Transition Rates of Coalescence Events during Double Phase Separation in Microgravity

Department of Physics and Astronomy, College of Charleston, Charleston, SC 29424, USA
CNRS, Institut de Chimie de la Matière Condensée de Bordeaux, ESEME, Université de Bordeaux, UPR 9048, F-33600 Pessac, France
Physique et Mécanique des Milieux Hétérogènes, UMR 7636 CNRS-ESPCI-Université Pierre et Marie Curie - Université Paris Diderot, 10 rue Vauquelin, 75005 Paris, France
Author to whom correspondence should be addressed.
Received: 15 June 2017 / Accepted: 30 June 2017 / Published: 6 July 2017
(This article belongs to the Special Issue Sub- and Supercritical Fluids and Green Chemistry)
Full-Text   |   PDF [4290 KB, uploaded 6 July 2017]   |  


Phase transition is a ubiquitous phenomenon in nature, science and technology. In general, the phase separation from a homogeneous phase depends on the depth of the temperature quench into the two-phase region. Earth’s gravity masks the details of phase separation phenomena, which is why experiments were performed under weightlessness. Under such conditions, the pure fluid sulphur hexafluoride (SF 6 ) near its critical point also benefits from the universality of phase separation behavior and critical slowing down of dynamics. Initially, the fluid was slightly below its critical temperature with the liquid matrix separated from the vapor phase. A 0.2 mK temperature quench further cooled down the fluid and produced a double phase separation with liquid droplets inside the vapor phase and vapor bubbles inside the liquid matrix, respectively. The liquid droplets and the vapor bubbles respective distributions were well fitted by a lognormal function. The evolution of discrete bins of different radii allowed the derivation of the transition rates for coalescence processes. Based on the largest transition rates, two main coalescence mechanisms were identified: (1) asymmetric coalescences between one small droplet of about 20 μ m and a wide range of larger droplets; and (2) symmetric coalescences between droplets of large and similar radii. Both mechanisms lead to a continuous decline of the fraction of small radii droplets and an increase in the fraction of the large radii droplets. Similar coalescence mechanisms were observed for vapor bubbles. However, the mean radii of liquid droplets exhibits a t 1 / 3 evolution, whereas the mean radii of the vapor bubbles exhibit a t 1 / 2 evolution. View Full-Text
Keywords: phase separation; microgravity; binary coalescence phase separation; microgravity; binary coalescence

Figure 1

This is an open access article distributed under the Creative Commons Attribution License which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited (CC BY 4.0).

Share & Cite This Article

MDPI and ACS Style

Oprisan, A.; Garrabos, Y.; Lecoutre, C.; Beysens, D. Measuring the Transition Rates of Coalescence Events during Double Phase Separation in Microgravity. Molecules 2017, 22, 1125.

Show more citation formats Show less citations formats

Note that from the first issue of 2016, MDPI journals use article numbers instead of page numbers. See further details here.

Related Articles

Article Metrics

Article Access Statistics



[Return to top]
Molecules EISSN 1420-3049 Published by MDPI AG, Basel, Switzerland RSS E-Mail Table of Contents Alert
Back to Top