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Chorng-shyan Chern - One of the best experts on this subject based on the ideXlab platform.
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Modeling the role of polymeric costabilizers in retarding Ostwald Ripening involved in styrene miniemulsions
Journal of the Taiwan Institute of Chemical Engineers, 2015Co-Authors: Chun-ta Lin, Chorng-shyan ChernAbstract:Abstract A thermodynamic approach dealing with a regular solution of monomer (styrene (ST) herein) and different polymeric costabilizers as the disperse phase of miniemulsion were used to develop a model that describes the Ostwald Ripening behavior involved in such a colloidal system. The validity of this model was verified by the Ostwald Ripening rate data obtained from ST miniemulsions stabilized by living polystyrene costabilizer (PSlc) or polystyrene costabilizer (PSc) upon aging at 25 ℃. PSlc is more effective in retarding the Ostwald Ripening process than PSc, though PSlc and PSc have comparable number-average molecular weights. The model can be also used to study the mutual interaction between monomer and polymeric costabilizer. Satisfactory modeling results achieved for ST miniemulsions using polymethyl methacrylate as the costabilizer further verify the general validity of the present model. Finally, the values of heat of mixing and interaction parameter between ST and different polymeric costabilizers were also determined.
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Modeling Ostwald Ripening rate of styrene miniemulsions stabilized by a homolog of n-alkane costabilizers
Journal of the Taiwan Institute of Chemical Engineers, 2015Co-Authors: Chun-ta Lin, Chorng-shyan ChernAbstract:The modified Kabal'nov equation developed by a thermodynamic approach dealing with a regular solution of monomer and costabilizer as the two-component disperse phase adequately describes the Ostwald Ripening rate data in a wide range of the volume fraction of costabilizer for styrene miniemulsions stabilized by a homolog of n-alkane costabilizers (CnH2n+2; n = 10, 12, 16, 18, 20, 24, 32) upon aging at 25 °C. The results show that the costabilizer with the shortest chain length (C10H22) is not hydrophobic enough to effectively retard the Ostwald Ripening process. The effectiveness of n-alkanes as costabilizer in suppressing the Ostwald Ripening process increases with increasing n-alkane molecular weight. Nevertheless, further increasing the n-alkane chain length from C24H50 to C32H66 does not lead to significant improvement in the effectiveness of n-alkane as costabilizer. The major characteristics of the modified Kabal'nov equation are also discussed in this work.
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Peculiar behavior of mixed costabilizers in retarding Ostwald Ripening of styrene miniemulsions
Journal of the Taiwan Institute of Chemical Engineers, 2014Co-Authors: Chun-ta Lin, S. Ganitri, R.h. Safitri, Chorng-shyan ChernAbstract:The Ostwald Ripening behavior of the three-component disperse phase styrene miniemulsions stabilized by mixed costabilizers of cetyl alcohol (CA)/n-alkanes (or dodecyl methacrylate (DMA)/n-alkanes) was investigated. The pseudo-two-component disperse phase miniemulsion model adequately described Ostwald Ripening rate data. In addition, the general validity of a universal correlation (i.e., the Ostwald Ripening parameter K1 is inversely proportional to the equivalent water solubility of bulk mixed costabilizers) was further confirmed by vast experimental data. For n-alkanes with lower molecular weight ( 226), miniemulsions stabilized by these two types of mixed costabilizers exhibited opposite Ostwald Ripening behavior.
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Characterization of Costabilizers in Retarding Ostwald Ripening of Monomer Miniemulsions
Journal of Dispersion Science and Technology, 2012Co-Authors: Yenny Meliana, Chun-ta Lin, Lilik Suprianti, Y. J. Huang, Chorng-shyan ChernAbstract:The Ostwald Ripening behavior of ST or MMA miniemulsions stabilized by various types of costabilizers upon aging at 25°C was investigated. The general validity of the quadratic empirical model with two parameters K1 and K2 was verified and it showed great potential to describe the general features of the Ostwald Ripening process involved in miniemulsions stabilized by a relatively wide range of volume fraction of costabilizer in the disperse phase. The greater the K1/RO,1 (or K2/RO,1) value, the more effective is the costabilizer in stabilizing miniemulsion droplets against the diffusional degradation process. RO,1 is the Ostwald Ripening rate corresponding to the single component of ST (or MMA). Some useful correlations of the K1/RO,1 (or K2/RO,1) data with the water solubility (or solubility parameter) of the bulk costabilizer were established. Polymeric costabilizers showed quite different behavior in stabilizing miniemulsions compared to low molecular weight costabilizers. Incorporation of hydrophilic...
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Effect of mixed costabilizers on Ostwald Ripening of monomer miniemulsions
Colloids and Surfaces A: Physicochemical and Engineering Aspects, 2011Co-Authors: Yenny Meliana, Chun-ta Lin, Lilik Suprianti, Yi Chia Huang, Chorng-shyan ChernAbstract:Abstract The role of the mixed costabilizers of cetyl alcohol (CA) and hexadecane (HD) in retarding Ostwald Ripening occurring in the three-component disperse phase monomer miniemulsions at 25 °C was investigated. The modified Kabalnov equation failed to describe the Ostwald Ripening behavior. Thus, the miniemulsion disperse phase comprising monomer (methyl methacrylate (MMA) or styrene (ST)) and the mixed costabilizers of CA and HD was simply treated as a pseudo-two-component disperse phase miniemulsion system. All the results that are self-consistent with one another justify the validity of the proposed pseudo-two component disperse phase miniemulsion model. A unique feature observed in this study is the synergistic effect of the mixed costabilizers of CA and HD in retarding the Ostwald Ripening process.
Chun-ta Lin - One of the best experts on this subject based on the ideXlab platform.
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Modeling the role of polymeric costabilizers in retarding Ostwald Ripening involved in styrene miniemulsions
Journal of the Taiwan Institute of Chemical Engineers, 2015Co-Authors: Chun-ta Lin, Chorng-shyan ChernAbstract:Abstract A thermodynamic approach dealing with a regular solution of monomer (styrene (ST) herein) and different polymeric costabilizers as the disperse phase of miniemulsion were used to develop a model that describes the Ostwald Ripening behavior involved in such a colloidal system. The validity of this model was verified by the Ostwald Ripening rate data obtained from ST miniemulsions stabilized by living polystyrene costabilizer (PSlc) or polystyrene costabilizer (PSc) upon aging at 25 ℃. PSlc is more effective in retarding the Ostwald Ripening process than PSc, though PSlc and PSc have comparable number-average molecular weights. The model can be also used to study the mutual interaction between monomer and polymeric costabilizer. Satisfactory modeling results achieved for ST miniemulsions using polymethyl methacrylate as the costabilizer further verify the general validity of the present model. Finally, the values of heat of mixing and interaction parameter between ST and different polymeric costabilizers were also determined.
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Modeling Ostwald Ripening rate of styrene miniemulsions stabilized by a homolog of n-alkane costabilizers
Journal of the Taiwan Institute of Chemical Engineers, 2015Co-Authors: Chun-ta Lin, Chorng-shyan ChernAbstract:The modified Kabal'nov equation developed by a thermodynamic approach dealing with a regular solution of monomer and costabilizer as the two-component disperse phase adequately describes the Ostwald Ripening rate data in a wide range of the volume fraction of costabilizer for styrene miniemulsions stabilized by a homolog of n-alkane costabilizers (CnH2n+2; n = 10, 12, 16, 18, 20, 24, 32) upon aging at 25 °C. The results show that the costabilizer with the shortest chain length (C10H22) is not hydrophobic enough to effectively retard the Ostwald Ripening process. The effectiveness of n-alkanes as costabilizer in suppressing the Ostwald Ripening process increases with increasing n-alkane molecular weight. Nevertheless, further increasing the n-alkane chain length from C24H50 to C32H66 does not lead to significant improvement in the effectiveness of n-alkane as costabilizer. The major characteristics of the modified Kabal'nov equation are also discussed in this work.
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Peculiar behavior of mixed costabilizers in retarding Ostwald Ripening of styrene miniemulsions
Journal of the Taiwan Institute of Chemical Engineers, 2014Co-Authors: Chun-ta Lin, S. Ganitri, R.h. Safitri, Chorng-shyan ChernAbstract:The Ostwald Ripening behavior of the three-component disperse phase styrene miniemulsions stabilized by mixed costabilizers of cetyl alcohol (CA)/n-alkanes (or dodecyl methacrylate (DMA)/n-alkanes) was investigated. The pseudo-two-component disperse phase miniemulsion model adequately described Ostwald Ripening rate data. In addition, the general validity of a universal correlation (i.e., the Ostwald Ripening parameter K1 is inversely proportional to the equivalent water solubility of bulk mixed costabilizers) was further confirmed by vast experimental data. For n-alkanes with lower molecular weight ( 226), miniemulsions stabilized by these two types of mixed costabilizers exhibited opposite Ostwald Ripening behavior.
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Characterization of Costabilizers in Retarding Ostwald Ripening of Monomer Miniemulsions
Journal of Dispersion Science and Technology, 2012Co-Authors: Yenny Meliana, Chun-ta Lin, Lilik Suprianti, Y. J. Huang, Chorng-shyan ChernAbstract:The Ostwald Ripening behavior of ST or MMA miniemulsions stabilized by various types of costabilizers upon aging at 25°C was investigated. The general validity of the quadratic empirical model with two parameters K1 and K2 was verified and it showed great potential to describe the general features of the Ostwald Ripening process involved in miniemulsions stabilized by a relatively wide range of volume fraction of costabilizer in the disperse phase. The greater the K1/RO,1 (or K2/RO,1) value, the more effective is the costabilizer in stabilizing miniemulsion droplets against the diffusional degradation process. RO,1 is the Ostwald Ripening rate corresponding to the single component of ST (or MMA). Some useful correlations of the K1/RO,1 (or K2/RO,1) data with the water solubility (or solubility parameter) of the bulk costabilizer were established. Polymeric costabilizers showed quite different behavior in stabilizing miniemulsions compared to low molecular weight costabilizers. Incorporation of hydrophilic...
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Effect of mixed costabilizers on Ostwald Ripening of monomer miniemulsions
Colloids and Surfaces A: Physicochemical and Engineering Aspects, 2011Co-Authors: Yenny Meliana, Chun-ta Lin, Lilik Suprianti, Yi Chia Huang, Chorng-shyan ChernAbstract:Abstract The role of the mixed costabilizers of cetyl alcohol (CA) and hexadecane (HD) in retarding Ostwald Ripening occurring in the three-component disperse phase monomer miniemulsions at 25 °C was investigated. The modified Kabalnov equation failed to describe the Ostwald Ripening behavior. Thus, the miniemulsion disperse phase comprising monomer (methyl methacrylate (MMA) or styrene (ST)) and the mixed costabilizers of CA and HD was simply treated as a pseudo-two-component disperse phase miniemulsion system. All the results that are self-consistent with one another justify the validity of the proposed pseudo-two component disperse phase miniemulsion model. A unique feature observed in this study is the synergistic effect of the mixed costabilizers of CA and HD in retarding the Ostwald Ripening process.
Sally M. Benson - One of the best experts on this subject based on the ideXlab platform.
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A continuum-scale representation of Ostwald Ripening in heterogeneous porous media
Journal of Fluid Mechanics, 2020Co-Authors: Charlotte Garing, Sally M. BensonAbstract:Ostwald Ripening is a pore-scale phenomenon that coarsens a dispersed phase until thermodynamic equilibrium. Based on our previous finding that multi-bubble equilibrium is possible and likely in complex porous media, we develop a new continuum-scale model for Ostwald Ripening in heterogeneous porous media. In this model, porous media with two different capillary pressure curves are put into contact, allowing only diffusive flow through the aqueous phase to redistribute a trapped gas phase. Results show that Ostwald Ripening can increase the gas saturation in one medium while decreasing the gas saturation in the other, even when the gas phase is trapped in pore spaces by capillary forces. We develop an analogous retardation factor to show that the characteristic time for Ostwald Ripening is about $10^{5}$ times slower than a single-phase diffusion problem due to the fact that separate-phase gas requires a much larger amount of mass transfer before equilibrium is established. An approximate solution has been developed to predict the saturation redistribution between the two media. The model has been validated by numerical simulation over a wide range of physical parameters. Millimetre to centimetre-scale systems come to equilibrium in years, ranging up to 10 000 years and longer for metre-scale systems. These findings are particularly relevant for geological $\text{CO}_{2}$ storage, where residual trapping is an important mechanism for immobilizing $\text{CO}_{2}$ . Our work demonstrates that Ostwald Ripening due to heterogeneity in porous media is slow and on a similar time scale compared to other processes that redistribute trapped $\text{CO}_{2}$ such as convective mixing.
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Pore-scale modelling of Ostwald Ripening
Journal of Fluid Mechanics, 2017Co-Authors: Jacques A. De Chalendar, Charlotte Garing, Sally M. BensonAbstract:In a saturated solution with dispersed clusters of a second phase, the mechanism by which the larger clusters grow at the expense of the smaller ones is called Ostwald Ripening. Although the mechanism is well understood in situations where multiple clusters of gas exist in a liquid solution, evolution is much more complicated to predict when the two phases interact with a solid matrix, since the solid plays a significant role in determining the shape of the interface. In this paper, we study capillary dominated regimes in porous media where the driving force is inter-cluster diffusion. By decomposing the Ostwald Ripening mechanism into two processes that operate on different time scales – the diffusion of solute gas in the liquid and the readjustment of the shape of the gas–liquid interface to accommodate a change in mass – we develop a sequential algorithm to solve for the evolution of systems with multiple gas ganglia. In the absence of a solid matrix, thermodynamic equilibrium is reached when all of the gas phase aggregates to form one large bubble. In porous media on the other hand, we find that Ripening can lead to equilibrium situations with multiple disconnected ganglia, and that evolution is highly dependent on initial conditions and the structure of the solid matrix. The fundamental difference between the two cases is in the relationship between mass and capillary pressure.
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Pore-scale Considerations on Ostwald Ripening in Rocks
Energy Procedia, 2017Co-Authors: Jacques A. De Chalendar, Charlotte Garing, Sally M. BensonAbstract:Abstract Residually trapped CO 2 is often assumed to be stable when simulating its long-term fate in geological storage reservoirs. Ostwald Ripening is a mechanism that could potentially cause remobilization. We compare the case of bubbles of gas in a free liquid to that of a solid porous matrix. Using a new continuous pore network model, we gain insights on Ostwald Ripening in rocks and estimate time scales of evolution of multi-ganglia systems. Evolution is found to be highly dependent on system initialization as well as on pore structure. For residually trapped CO 2 in homogeneous rocks, a stable equilibrium is conceptually possible.
Charlotte Garing - One of the best experts on this subject based on the ideXlab platform.
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A continuum-scale representation of Ostwald Ripening in heterogeneous porous media
Journal of Fluid Mechanics, 2020Co-Authors: Charlotte Garing, Sally M. BensonAbstract:Ostwald Ripening is a pore-scale phenomenon that coarsens a dispersed phase until thermodynamic equilibrium. Based on our previous finding that multi-bubble equilibrium is possible and likely in complex porous media, we develop a new continuum-scale model for Ostwald Ripening in heterogeneous porous media. In this model, porous media with two different capillary pressure curves are put into contact, allowing only diffusive flow through the aqueous phase to redistribute a trapped gas phase. Results show that Ostwald Ripening can increase the gas saturation in one medium while decreasing the gas saturation in the other, even when the gas phase is trapped in pore spaces by capillary forces. We develop an analogous retardation factor to show that the characteristic time for Ostwald Ripening is about $10^{5}$ times slower than a single-phase diffusion problem due to the fact that separate-phase gas requires a much larger amount of mass transfer before equilibrium is established. An approximate solution has been developed to predict the saturation redistribution between the two media. The model has been validated by numerical simulation over a wide range of physical parameters. Millimetre to centimetre-scale systems come to equilibrium in years, ranging up to 10 000 years and longer for metre-scale systems. These findings are particularly relevant for geological $\text{CO}_{2}$ storage, where residual trapping is an important mechanism for immobilizing $\text{CO}_{2}$ . Our work demonstrates that Ostwald Ripening due to heterogeneity in porous media is slow and on a similar time scale compared to other processes that redistribute trapped $\text{CO}_{2}$ such as convective mixing.
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Pore-scale modelling of Ostwald Ripening
Journal of Fluid Mechanics, 2017Co-Authors: Jacques A. De Chalendar, Charlotte Garing, Sally M. BensonAbstract:In a saturated solution with dispersed clusters of a second phase, the mechanism by which the larger clusters grow at the expense of the smaller ones is called Ostwald Ripening. Although the mechanism is well understood in situations where multiple clusters of gas exist in a liquid solution, evolution is much more complicated to predict when the two phases interact with a solid matrix, since the solid plays a significant role in determining the shape of the interface. In this paper, we study capillary dominated regimes in porous media where the driving force is inter-cluster diffusion. By decomposing the Ostwald Ripening mechanism into two processes that operate on different time scales – the diffusion of solute gas in the liquid and the readjustment of the shape of the gas–liquid interface to accommodate a change in mass – we develop a sequential algorithm to solve for the evolution of systems with multiple gas ganglia. In the absence of a solid matrix, thermodynamic equilibrium is reached when all of the gas phase aggregates to form one large bubble. In porous media on the other hand, we find that Ripening can lead to equilibrium situations with multiple disconnected ganglia, and that evolution is highly dependent on initial conditions and the structure of the solid matrix. The fundamental difference between the two cases is in the relationship between mass and capillary pressure.
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Pore-scale Considerations on Ostwald Ripening in Rocks
Energy Procedia, 2017Co-Authors: Jacques A. De Chalendar, Charlotte Garing, Sally M. BensonAbstract:Abstract Residually trapped CO 2 is often assumed to be stable when simulating its long-term fate in geological storage reservoirs. Ostwald Ripening is a mechanism that could potentially cause remobilization. We compare the case of bubbles of gas in a free liquid to that of a solid porous matrix. Using a new continuous pore network model, we gain insights on Ostwald Ripening in rocks and estimate time scales of evolution of multi-ganglia systems. Evolution is found to be highly dependent on system initialization as well as on pore structure. For residually trapped CO 2 in homogeneous rocks, a stable equilibrium is conceptually possible.
P Taylor - One of the best experts on this subject based on the ideXlab platform.
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Ostwald Ripening in emulsions
Colloids and Surfaces A: Physicochemical and Engineering Aspects, 1995Co-Authors: P TaylorAbstract:Abstract The rates of Ostwald Ripening in decane O/W emulsions were measured as a function of sodium dodecylsulphate concentration and of droplet volume fraction. It was found that the presence of micelles had only a small but systematic effect upon the rate of Ripening, contrary to expectation, where the presence of micelles might be expected to aid the process of Ripening through solubilization of oil. This small effect was discussed in terms of Kabal'nov's treatment of the process. It was concluded that the micelles were not in true equilibrium with the material diffusing from the droplets undergoing Ostwald Ripening, and that only a small fraction of the micelles could, at any time, solubilize material from the droplets. This would lead to the reduced effect of micellar concentration on the rate of Ripening. No systematic variation in rate was found with the volume fraction of the oil phase in the range 0–0.3. Theoretical treatments due to a number of authors suggest that the rate should increase by a factor of 2.5 in this range of volume fractions. The lack of volume fraction dependence was attributed to the presence of micelles which would appear to mask the effect of interactions between neighbouring diffusion fields surrounding the droplets.
