Phase separation kinetics of rigid‐rod polymers during coagulation

Nelson, Donald S.; Soane, David S.

doi:10.1002/pen.760332406

Cited by 5 publications

(3 citation statements)

References 13 publications

(2 reference statements)

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“…Kinetics of phase separation of poly(p-phenylenebenzobisoxazole) in methanesulfonic acid were examined by the time-resolved light scattering measurements. 19 Diffusion of the water vapor into the polymer solution film resulted in phase separation. These solutions appeared to undergo a spinodal decomposition-like phase separation.…”

Section: Introductionmentioning

confidence: 99%

Membrane formation via phase separation induced by penetration of nonsolvent from vapor phase. I. Phase diagram and mass transfer process

Matsuyama

Teramoto

Nakatani

et al. 1999

J. Appl. Polym. Sci.

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ABSTRACT:The isothermal phase diagram for poly(vinylidene fluoride)/dimethyl formamide/water system was derived. The binodal and spinodal were calculated based on the Flory-Huggins theory and the calculated binodal was approximately in agreement with the experimental data of the cloud points. The isothermal crystallization line was also obtained according to the theory of melting point depression. Mass transfer of the three components during membrane formation by the precipitation from the vapor phase has been analyzed. During this process, phase separation of the polymer solution is induced by the penetration of water vapor in the solution. The calculated result on the changes of the cast film weights indicated the good agreement with the experimental data. The time-course of the polymer concentration profile in the film was calculated for various cases of different humidity of the vapor phase and different initial polymer concentration.

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Section: Introductionmentioning

confidence: 99%

Membrane formation via phase separation induced by penetration of nonsolvent from vapor phase. I. Phase diagram and mass transfer process

Matsuyama

Teramoto

Nakatani

et al. 1999

J. Appl. Polym. Sci.

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“…There is a competition between aggregation of NPs and coarsening of domains (decrease of interfacial area between the phase‐separated domains by interracial tension) in the evolution of G ′ in the later stages of phase separation. The former tends to increase the G ′ and the latter tends to decrease it . For all samples containing NPs, except for the sample containing 2% M‐CNW, coarsening could overcome the aggregation effect in the evolution of G ′, leading to a reduction in G ′ in the later stages of phase separation.…”

Section: Resultsmentioning

confidence: 95%

Effect of selective localization of cellulose nanowhiskers on viscoelastic phase separation

Shahrezaei

Goharpey

Yeganeh

2017

Polymer Engineering & Sci

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Viscoelastic phase separation (VPS) is a fundamental physical phenomenon that creates percolated network structure in dynamically asymmetric mixtures. The object of this study was to investigate the effect of rod shape nanoparticles with different surface chemistries on VPS in the polystyrene/poly(vinyl methyl ether), PS/PVME, blend. For this purpose, hydrophilic (CNWs) and hydrophobic (M‐CNWs) cellulose nanowhiskers (CNWs) were prepared to be used as nanorods. Rheological measurments were employed to investigate the effect of nanowhiskers on phase separation temperature, kinetics of phase separation, and dynamic asymmetry. The evolution of morphology during the phase separation at a fixed quench depth was assessed using polarized optical microscopy. The nanowhiskers were effective in decreasing the correlation length, which slowed down the phase separation. CNWs self‐assembled into the PVME‐rich phase during the phase separation, which led to a decrease in the dynamic asymmetry and beyond a critical volume fraction of CNWs, the VPS mechanism changed to spinodal decomposition (SD). However, in the presence of M‐CNW, the localization of M‐CNWs into the PS‐rich phase enhanced the dynamic asymmetry and at 2 vol% M‐CNWs, the induced PS‐rich network by VPS was arrested. The linear and non‐linear viscoelastic behavior of the samples were studied as well. POLYM. ENG. SCI., 58:928–942, 2018. © 2017 Society of Plastics Engineers

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“…The rotational dynamics of nematic solutions of rodlike polymers are of particular interest in areas such as processing of fibers 1 and thin films 2 and in electrorheological (ER) fluids, 3 where the orientation of the molecules controls the response and properties of the solution. Modeling of such problems usually involves fitting the rotational diffusivity to experimental data.…”

Section: Introductionmentioning

confidence: 99%

Molecular Weight Dependence of the Rotational Diffusivity of Rodlike Polymers in Concentrated Nematic Solutions

2005

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The dynamics of rodlike polymer molecules in the nematic phase are mainly controlled by the rotational diffusivity, D r, which is highly sensitive to molecular weight. However, few experimental determinations of D r for polymer solutions at concentrations in the nematic phase have been made. We invoke Doi's theory of liquid crystalline polymer rheology to extract D r from experimental measurements of the transverse Miesowicz viscosity, ηc, of nematic solutions. Transverse Miesowicz viscosities were measured for a series of poly(n-hexyl isocyanate) (PHIC) polymers at fixed dimensionless concentration (c/c* = 1.25) in p-xylene, by orienting the director with a high dc electric field. The rotational diffusivity of PHIC was found to be independent of shear rate and proportional to M w -4.95±0.29. This scaling is in excellent agreement with Doi's molecular theory, which predicts that D r scales as M -5 at fixed c/c*. The experimental values of D r were compared with theoretical values calculated a priori from molecular dimensions and the solution concentration. The numerical constant β which multiplies Doi's predicted D r was found to be of order 101 for the nematic PHIC solutions, in contrast with values of order 103 reported for semidilute solutions of rodlike molecules.

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Phase separation kinetics of rigid‐rod polymers during coagulation

Cited by 5 publications

References 13 publications

Membrane formation via phase separation induced by penetration of nonsolvent from vapor phase. I. Phase diagram and mass transfer process

Membrane formation via phase separation induced by penetration of nonsolvent from vapor phase. I. Phase diagram and mass transfer process

Effect of selective localization of cellulose nanowhiskers on viscoelastic phase separation

Molecular Weight Dependence of the Rotational Diffusivity of Rodlike Polymers in Concentrated Nematic Solutions

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