scholarly journals Phase Separation by Spinodal Decomposition in Polymer Blends Under a Single and Double Quench: a Computational Study

2021 ◽  
Author(s):  
Tuyet Tran
Keyword(s):  
Phase Separation ◽  
Polymer Blends ◽  
Spinodal Decomposition ◽  
Computational Study ◽  
Early Stage ◽  
Critical Factor ◽  
Domain Size ◽  
Secondary Structures ◽  
Numerical Results ◽  
Numerical Work

A mathematical model and computer simulations are used to describe the dynamics of thermally induced phase separation (TIPS) by spinodal decomposition for polymer blends (single quench and double quench) using the nonlinear Cahn-Hilliard theory and the Flory-Huggins-de Gennes free energy. The importance of TIPS is to enhance material properties such as toughness, impact resistance and elasticity. Therefore, controlling the morphology is a critical factor in optimizing performance. The numerical results for the single quench are consistent with known characteristics of phase separation by spinodal decomposition observed in polymer blends. The numerical results for double quenching replicate recently published experimental and numerical work. Under a double quench the numerical work shows that a critical quench depth exists before secondary phase separation occurs, the growth rate of the primary and secondary structures are dependent on domain size and early stage dynamics for the secondary structures, after the second jump, appears to follow the linear Cahn-Hilliard theory.

scholarly journals Phase Separation by Spinodal Decomposition in Polymer Blends Under a Single and Double Quench: a Computational Study

2021 ◽  
Author(s):  
Tuyet Tran
Keyword(s):  
Phase Separation ◽  
Polymer Blends ◽  
Spinodal Decomposition ◽  
Computational Study ◽  
Early Stage ◽  
Critical Factor ◽  
Domain Size ◽  
Secondary Structures ◽  
Numerical Results ◽  
Numerical Work

A mathematical model and computer simulations are used to describe the dynamics of thermally induced phase separation (TIPS) by spinodal decomposition for polymer blends (single quench and double quench) using the nonlinear Cahn-Hilliard theory and the Flory-Huggins-de Gennes free energy. The importance of TIPS is to enhance material properties such as toughness, impact resistance and elasticity. Therefore, controlling the morphology is a critical factor in optimizing performance. The numerical results for the single quench are consistent with known characteristics of phase separation by spinodal decomposition observed in polymer blends. The numerical results for double quenching replicate recently published experimental and numerical work. Under a double quench the numerical work shows that a critical quench depth exists before secondary phase separation occurs, the growth rate of the primary and secondary structures are dependent on domain size and early stage dynamics for the secondary structures, after the second jump, appears to follow the linear Cahn-Hilliard theory.

scholarly journals A computational study of phase separation in polymer solutions under a double quench

2021 ◽  
Author(s):  
Ehsan Hosseini
Keyword(s):  
Phase Separation ◽  
Polymer Solution ◽  
Spinodal Decomposition ◽  
Computational Study ◽  
Stable State ◽  
Thermal Quenching ◽  
Nucleation And Growth ◽  
Two Dimensions ◽  
Numerical Work ◽  
Binary Polymer

Polymer-dispersed liquid crystals (PDLCs) are a relatively new class of materials used for many applications ranging from switchable windows to projection displays. PDLSs are formed by spinodal decomposition induced by thermal quenching or polymerization. The objective of the present study is to introduce a new mechanism of phase separation in a binary polymer solution and develop a mathematical model and computer simulation to describe the phase separation during the early and intermediate stages of nucleation and growth and spinodal decomposition induced by thermal double quenching. The growth equilibrium limits of phase separation as well as phase transition are calculated by taking into consideration the Flory-Huggins theory for the free energy of mixing. A two step quench is modeled using Cahn-Hilliard theory for asymmetric binary polymer solution which is quenched from a stable state in the one-phase region to a metastable region where nucleation and growth occurs. The solution is allowed to coarsen for different time periods before a second quench was applied to a point further inside the phase diagram. The numerical results in two dimensions replicate the experimental and numerical work that has been recently done and published.

scholarly journals A computational study of phase separation in polymer solutions under a double quench

2021 ◽  
Author(s):  
Ehsan Hosseini
Keyword(s):  
Phase Separation ◽  
Polymer Solution ◽  
Spinodal Decomposition ◽  
Computational Study ◽  
Stable State ◽  
Thermal Quenching ◽  
Nucleation And Growth ◽  
Two Dimensions ◽  
Numerical Work ◽  
Binary Polymer

Polymer-dispersed liquid crystals (PDLCs) are a relatively new class of materials used for many applications ranging from switchable windows to projection displays. PDLSs are formed by spinodal decomposition induced by thermal quenching or polymerization. The objective of the present study is to introduce a new mechanism of phase separation in a binary polymer solution and develop a mathematical model and computer simulation to describe the phase separation during the early and intermediate stages of nucleation and growth and spinodal decomposition induced by thermal double quenching. The growth equilibrium limits of phase separation as well as phase transition are calculated by taking into consideration the Flory-Huggins theory for the free energy of mixing. A two step quench is modeled using Cahn-Hilliard theory for asymmetric binary polymer solution which is quenched from a stable state in the one-phase region to a metastable region where nucleation and growth occurs. The solution is allowed to coarsen for different time periods before a second quench was applied to a point further inside the phase diagram. The numerical results in two dimensions replicate the experimental and numerical work that has been recently done and published.

Distinctive phase separation dynamics of polymer blends: roles of Janus nanoparticles

2019 ◽  
Vol 21 (5) ◽  
pp. 2651-2658 ◽  
Author(s):  
Qing Li ◽  
Liquan Wang ◽  
Jiaping Lin ◽  
Liangshun Zhang
Keyword(s):  
Phase Separation ◽  
Polymer Blends ◽  
Spinodal Decomposition ◽  
Late Stage ◽  
Early Stage ◽  
Janus Nanoparticles

The present work demonstrates that Janus nanoparticles uniquely promote the phase separation of polymer blends at the early stage of spinodal decomposition, but impede it at the late stage.

Kinetics of phase separation at the early stage of spinodal decomposition in epoxy resin modified with PEI blends

2008 ◽  
Vol 287 (1) ◽  
pp. 23-28 ◽  
Author(s):  
Wenjun Gan ◽  
Yingfeng Yu ◽  
Xiaoyun Liu ◽  
Minghai Wang ◽  
Shanjun Li
Keyword(s):  
Phase Separation ◽  
Epoxy Resin ◽  
Spinodal Decomposition ◽  
Early Stage ◽  
Kinetics Of

scholarly journals A computational study of surface-directed phase separation in polymer blends under temperature gradient

2021 ◽  
Author(s):  
Mohammad Tabatabaieyazdi
Keyword(s):  
Growth Rate ◽  
Phase Separation ◽  
Temperature Gradient ◽  
Long Range ◽  
Spinodal Decomposition ◽  
Surface Potential ◽  
Short Range ◽  
Computational Study ◽  
Polymeric Materials ◽  
Partial Wetting

To apprehend the real industrial behavior of polymeric materials phase separation phenomenon, the nonlinear Cahn-Hilliard theory incorporating the Flory-Huggins-de Gennes free energy theory was used to study the non-uniform thermal-induced phase separation phenomenon in a symmetric binary polymer blend in which surface(s) with short- and long-range attraction to one polymer component compete with temperature gradient effects. The numerical results indicate that an increase of diffusion coefficient value will increase the rate of phase separation in the bulk but will decrease the growth rate of the wetting layer on the surface regardless of the surface potential strength. Also, the morphology transition from complete to partial wetting of the surface with short range surface attraction is successfully demonstrated. However, no partial wetting is observed for the surface with long-range potential. For shallow quenches, first, a growth rate of t 0.5 is observed in the early stage of spinodal decomposition phase separation at the surface and then a decline in the growth rate to t 0.13 in the intermediate stage occurred. For short- and long-range surface potential, the growth rate value of t 0.33 obtained in the bulk. The morphology results of temperature gradient effect on surface directed spinodal decomposition in short-range, long- range and multiple-surface attraction cases have been presented for the first time. It is realized that regardless of surface potential magnitude, surface enrichment is increased by higher temperature gradient (deep quenches on the side with no surface attraction). The studied models would provide more in depth understanding of polymer blendiprocesses.

Partial cation-order and early-stage, phase separation in phase W, Li x Co 1− x O: 0.075≤ x ≤0.24−0.31

2009 ◽  
Vol 465 (2106) ◽  
pp. 1829-1841 ◽  
Author(s):  
Y. Wu ◽  
D. Pasero ◽  
E.E. McCabe ◽  
Y. Matsushima ◽  
A.R. West
Keyword(s):  
Phase Separation ◽  
Early Stage ◽  
Domain Size ◽  
Solid Solution Phase ◽  
X Ray ◽  
Cation Order ◽  
Transmission Electron ◽  
X Ray Absorption ◽  
Li Content ◽  
Disordered Regions

We report the characterization using X-ray and neutron powder diffraction, transmission electron microscopy and extended X-ray absorption fine structure of a new, partially ordered rock-salt-like solid solution phase Li x Co 1− x O: 0.075≤ x ≤0.24−0.31. The cation stacking sequence along [111] consists of alternating planes of Co and Co/Li. Nano-sized domains of this cation-ordered phase appear alongside disordered regions; domain size increases from 2 to 8 nm with increasing Li content. Compositions of ordered and disordered regions are Li- and Co-rich, respectively, and, therefore, the phase exhibits frozen-in, incipient phase separation. This microstructure could be considered as a precursor to precipitation of fully ordered, rhombohedral LiCoO 2 .

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