Investigating the evolution of the phase behavior of AOT-based w/o microemulsions in dodecane as a function of droplet volume fraction

2012 ◽  
Vol 372 (1) ◽  
pp. 45-51 ◽  
Author(s):  
R. Ganguly ◽  
N. Choudhury
Keyword(s):  
Phase Behavior ◽  
Volume Fraction ◽  
Droplet Volume

scholarly journals Effects of Polydispersity on the Phase Behavior of Additive Hard Spheres in Solution

Molecules ◽  
2021 ◽  
Vol 26 (6) ◽  
pp. 1543
Author(s):  
Luka Sturtewagen ◽  
Erik van der Linden
Keyword(s):  
Phase Behavior ◽  
Critical Point ◽  
Volume Fraction ◽  
Hard Spheres ◽  
Second Virial Coefficient ◽  
Two Phase ◽  
Different Types ◽  
Asymmetric Partitioning ◽  
Average Size ◽  
Liquid Liquid Phase Separation

The ability to separate enzymes, nucleic acids, cells, and viruses is an important asset in life sciences. This can be realised by using their spontaneous asymmetric partitioning over two macromolecular aqueous phases in equilibrium with one another. Such phases can already form while mixing two different types of macromolecules in water. We investigate the effect of polydispersity of the macromolecules on the two-phase formation. We study theoretically the phase behavior of a model polydisperse system: an asymmetric binary mixture of hard spheres, of which the smaller component is monodisperse and the larger component is polydisperse. The interactions are modelled in terms of the second virial coefficient and are assumed to be additive hard sphere interactions. The polydisperse component is subdivided into sub-components and has an average size ten times the size of the monodisperse component. We calculate the theoretical liquid–liquid phase separation boundary (the binodal), the critical point, and the spinodal. We vary the distribution of the polydisperse component in terms of skewness, modality, polydispersity, and number of sub-components. We compare the phase behavior of the polydisperse mixtures with their concomittant monodisperse mixtures. We find that the largest species in the larger (polydisperse) component causes the largest shift in the position of the phase boundary, critical point, and spinodal compared to the binary monodisperse binary mixtures. The polydisperse component also shows fractionation. The smaller species of the polydisperse component favor the phase enriched in the smaller component. This phase also has a higher-volume fraction compared to the monodisperse mixture.

Alignment of Nanoplates in Lamellar Diblock Copolymer Domains and the Effect of Particle Volume Fraction on Phase Behavior

2018 ◽  
Vol 7 (12) ◽  
pp. 1400-1407 ◽  
Author(s):  
Nadia M. Krook ◽  
Jamie Ford ◽  
Manuel Maréchal ◽  
Patrice Rannou ◽  
Jeffrey S. Meth ◽  
...  
Keyword(s):  
Phase Behavior ◽  
Diblock Copolymer ◽  
Volume Fraction ◽  
Particle Volume Fraction ◽  
Particle Volume

scholarly journals Phase Behavior of Melts of Diblock-Copolymers with One Charged Block

Polymers ◽  
2019 ◽  
Vol 11 (6) ◽  
pp. 1027 ◽  
Author(s):  
Alexey A. Gavrilov ◽  
Alexander V. Chertovich ◽  
Igor I. Potemkin
Keyword(s):  
Phase Diagram ◽  
Phase Behavior ◽  
Electrostatic Interactions ◽  
Diblock Copolymers ◽  
Volume Fraction ◽  
Microphase Separation ◽  
Dissipative Particle Dynamics ◽  
Homogeneous Structure ◽  
Electrostatic Energy ◽  
Ordered Structures

In this work, we investigated the phase behavior of melts of block-copolymers with one charged block by means of dissipative particle dynamics with explicit electrostatic interactions. We assumed that all the Flory–Huggins χ parameters were equal to 0. We showed that the charge- correlation attraction solely can cause microphase separation with a long-range order; a phase diagram was constructed by varying the volume fraction of the uncharged block and the electrostatic interaction parameter λ (dimensionless Bjerrum length). The obtained phase diagram was compared to the phase diagram of “equivalent” neutral diblock-copolymers with the non-zero χ-parameter between the beads of different blocks. The neutral copolymers were constructed by grafting the counterions to the corresponding co-ions of the charged block with further switching off the electrostatic interactions. Surprisingly, the differences between these phase diagrams are rather subtle; the same phases in the same order are observed, and the positions of the order-disorder transition ODT points are similar if the λ-parameter is considered as an “effective” χ-parameter. Next, we studied the position of the ODT for lamellar structure depending on the chain length N. It turned out that while for the uncharged diblock copolymer the product χcrN was almost independent of N, for the diblock copolymers with one charged block we observed a significant increase in λcrN upon increasing N. This can be attributed to the fact that the counterion entropy prevents the formation of ordered structures, and its influence is more pronounced for longer chains since they undergo the transition to ordered structures at smaller values of λ, when the electrostatic energy becomes comparable to kbT. This was supported by studying the ODT in diblock-copolymers with charged blocks and counterions cross-linked to the charged monomer units. The ODT for such systems was observed at significantly lower values of λ, with the difference being more pronounced at longer chain lengths N. The fact that the microphase separation is observed even at zero Flory–Huggins parameter can be used for the creation of “high-χ” copolymers: The incorporation of charged groups (for example, ionic liquids) can significantly increase the segregation strength. The diffusion of counterions in the obtained ordered structures was studied and compared to the case of a system with the same number of charged groups but a homogeneous structure; the diffusion coefficient along the lamellar plane was found to be higher than in any direction in the homogeneous structure.

The study of droplet deformation and droplet volume fraction in an aero-engine bearing chamber

2018 ◽  
Vol 233 (6) ◽  
pp. 2264-2277
Author(s):  
Long Fang ◽  
Guoding Chen
Keyword(s):  
Volume Fraction ◽  
Theoretical Calculations ◽  
Research Work ◽  
Droplet Volume ◽  
Droplet Deformation ◽  
Two Phase ◽  
Aero Engine ◽  
Model Equations ◽  
Breakup Model ◽  
Engine Bearing

Inside an aero-engine bearing chamber, the shape, velocity, and temperature of each droplet shed from roller elements keep changing under the actions of the rotating airflow. Research on droplet deformation, droplet motion, and droplet volume fraction is fundamental to the understanding of the complex two-phase flow in an aero-engine bearing chamber. In this paper, the modified Taylor analogy breakup model, equations of temperature and motion are established to obtain the size, temperature, and velocity of a deformed droplet. Subsequently, a method is presented to solve for the droplet volume fraction in a bearing chamber based on the size and motion parameters of deformed droplets. In the end, a simplified bearing chamber experimental setup has been constructed. Comparisons between the experimental results and theoretical calculations show a good match based upon the research analogy used. The research work in this paper can provide theoretical foundations for the analyses of heat exchange and lubrication in bearing chambers. This also has great significance in realizing the rigorous design required for the lubrication system of an aero-engine.

Phase Behavior and Shrinking Kinetics of Thermo-Reversible Poly(N-Isopropylacrylamide-2-Hydroxyethyl Methacrylate)

2009 ◽  
Vol 1190 ◽  
Author(s):  
Christine M Leon ◽  
Francisco J Solis ◽  
Brent L Vernon
Keyword(s):  
Phase Separation ◽  
Phase Behavior ◽  
Volume Fraction ◽  
Hydroxyethyl Methacrylate ◽  
Dilute Solution ◽  
Complex Phase ◽  
Second Stage ◽  
Double Exponential ◽  
Liquid Solutions ◽  
Kinetics Of

AbstractWe study the thermodynamic properties of solutions of the physically gelling poly(N-isopropylacrylamide-2-hydroxyethyl methacrylate) [poly(NIPPAm-HEMA)]. We construct its phase diagram and characterize its kinetics of phase separation. This material belongs to a class of thermosensitive, “smart” polymers, that exhibit complex phase behavior. The copolymer studied is liquid at low temperatures and undergoes phase separation near 28°C, with negligible dependence on concentration. Above the transition temperature we observe coexistence between a polymer-dilute solution and a gel. We show that, upon quick heating, liquid solutions form a homogeneous gel that phase separates (shrinks) from a dilute polymer solution. We find that the evolution of the gel volume fraction is well described by a double exponential decay, indicating the presence of two shrinking regimes in a close parallel to the behavior of chemically cross-linked gels. The first stage is characterized by quick water ejection. In the second stage, slower shrinking is observed associated with internal reorganization of the polymers that allows the creation of gel-forming contacts.

Characterization of the volume fraction of soft deformable microgels by means of small-angle neutron scattering with contrast variation

Soft Matter ◽  
2021 ◽  
Author(s):  
Andrea Scotti
Keyword(s):  
Neutron Scattering ◽  
Phase Behavior ◽  
Small Angle ◽  
Small Angle Neutron Scattering ◽  
Volume Fraction ◽  
Contrast Variation ◽  
Thermodynamic Variable

The volume occupied by colloids in a suspension - namely the volume fraction - is the thermodynamic variable that determines the phase behavior of these systems. While for hard incompressible...

W/O/W emulsions with high internal droplet volume fraction

2012 ◽  
Vol 27 (1) ◽  
pp. 30-41 ◽  
Author(s):  
Fernando Leal-Calderon ◽  
Stephen Homer ◽  
Agustina Goh ◽  
Leif Lundin
Keyword(s):  
Volume Fraction ◽  
Droplet Volume

scholarly journals Phase Behavior and Phase Diagram of Polystyrene-b-Poly(Perfluorooctylethyl Acrylates)

Polymers ◽  
2020 ◽  
Vol 12 (4) ◽  
pp. 819
Author(s):  
Yu Shao ◽  
Hui Dai ◽  
Meng Zhao ◽  
Bin Li ◽  
Jianan Yao ◽  
...  
Keyword(s):  
Phase Diagram ◽  
Phase Behavior ◽  
Volume Fraction ◽  
Molecular Design ◽  
Modern Society ◽  
Advanced Materials ◽  
Structural Formation ◽  
X Ray ◽  
Transmission Electron ◽  
The Matrix

Fluorocontaining polymers bearing special properties are unique and important materials in modern society. In this work, we focused on the phase behavior and phase diagram of poly(styrene-block-perfluorooctylethyl acrylate) with a volume fraction varying from 0.2 to 0.8. Small-angle X-ray scattering and transmission electron microscopy showed the phase formation in the sequence of hexagonally packed cylinders (HEX) to lamellar layers (LAM) to inverse hexagonally packed cylinders (iHEX) in this series of block polymers. Wide-angle X-ray diffraction experiments proved that the fluorodomains of the LAM phases and the matrix of iHEX phases contained layered structures formed by the crystallization of fluorosegments. During heating, the self-assembled lattice remained intact even after the melting of fluorodomain, with barely changed lattice parameters. Such hierarchical structural formation was understood by chain conformation and domain interaction, which may provide new insight into the molecular design of advanced materials.

Chemical partitioning of elements in Ni-base MC-carbide reinforced eutetic superalloys

1983 ◽  
Vol 41 ◽  
pp. 250-251
Author(s):  
E. F. Koch ◽  
E. L. Hall ◽  
S. W. Yang
Keyword(s):  
Alloy Composition ◽  
Volume Fraction ◽  
Lattice Mismatch ◽  
Turbine Blades ◽  
Eutectic Alloys ◽  
Alloy Matrix ◽  
X Ray ◽  
Gas Turbine Blades ◽  
Analytical Electron ◽  
Analytical Electron Microscope

The plane-front solidified eutectic alloys consisting of aligned tantalum monocarbide fibers in a nickel alloy matrix are currently under consideration for future aircraft and gas turbine blades. The MC fibers provide exceptional strength at high temperatures. In these alloys, the Ni matrix is strengthened by the precipitation of the coherent γ' phase (ordered L12 structure, nominally Ni3Al). The mechanical strength of these materials can be sensitively affected by overall alloy composition, and these strength variations can be due to several factors, including changes in solid solution strength of the γ matrix, changes in they γ' size or morphology, changes in the γ-γ' lattice mismatch or interfacial energy, or changes in the MC morphology, volume fraction, thermal stability, and stoichiometry. In order to differentiate between these various mechanisms, it is necessary to determine the partitioning of elemental additions between the γ,γ', and MC phases. This paper describes the results of such a study using energy dispersive X-ray spectroscopy in the analytical electron microscope.

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