Refined calculation of the phase separation behavior of sheared polymer blends: closed miscibility gaps within two ranges of shear rates

Horst, Roland; Wolf, Bernhard

doi:10.1021/ma00073a022

Cited by 42 publications

(31 citation statements)

References 13 publications

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“…Horst and Wolf24–26 once predicted the possibility of existence of a closed immiscibility island and shear‐induced mixing in an A/B‐type blend. They introduced an item of elastic energy ( E s ) stemming from the molecular configuration change under shear field into the Flory–Huggins mean‐field theory and built the phase diagram of A/B blend under shear field.…”

Section: Discussionmentioning

confidence: 99%

Effect of shear flow on the phase‐separation behavior in a blend of polystyrene and polyvinyl methyl ether

Lei¹,

Li²,

Yang³

et al. 2003

J Polym Sci B Polym Phys

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The phase behavior and phase‐separation dynamics of polystyrene/polyvinyl methyl ether (PS/PVME) blend with a critical composition of 70 vol % PVME were examined with a light scattering technique under a shear‐rate range of 0.1–40 s−1. If the shear rates were less than 8 s−1 and the starting temperatures of the measurement were 343 and 383 K, respectively, two cloud points were observed, whereas after the shear rate was higher than 8 s−1, only one cloud point existed, 20 K higher than that of the static state of the blend. Investigation of the phase‐separation dynamics at 443 K suggested that in the vorticity direction the phase‐separation behavior at the early stage and the later stage can be explained by Cahn–Hilliard linearized theory and the exponent growth law, respectively. Phase separation occurs after a shearing time, which was called a delay time τd. The delayed time τd, the apparent diffusion coefficient, and the exponent term of the blend show strong dependence on shear rates. A theoretical prediction of the phase behavior of PS/PVME under a shear flow field by introducing an elastic energy term into Flory's equation‐of‐state theory was made, and the prediction was consistent with the experimental results. © 2003 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 41: 661–669, 2003

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Section: Discussionmentioning

confidence: 99%

Effect of shear flow on the phase‐separation behavior in a blend of polystyrene and polyvinyl methyl ether

Lei¹,

Li²,

Yang³

et al. 2003

J Polym Sci B Polym Phys

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“…Another approach is based on the lattice model in which, the Flory-Huggins interaction parameter of polymer solutions is modified for the flow condition [18]. The third approach is to apply the concept of non-equilibrium thermodynamics to flowing polymer solutions [1,[19][20][21][22][23][24][25][26][27]. Local equilibrium state is assumed for all internal points of the flowing solution under stress, similar to solids.…”

Section: Phase Diagram Analysismentioning

confidence: 99%

“…He also used upper convected maxwell model (UCM) to justify his results, however, he did mention that the change in conformational tensor must be used for other models to estimate ∆G E [28]. Although applying Marrucci's equation is limited to low ranges of chain deformation and polymer concentration, it has been applied to more concentrated systems such as polymer blends [20][21][22].…”

Section: Review Of Previous Workmentioning

confidence: 99%

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Predicting flow induced change in phase diagram of polymer solutions in simple shear flow

2009

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The change in the phase diagram of polymer mixtures under flow is an important issue since flow may promote mixing or demixing of the phases in a polymer mixture. This work, compared to previous studies, presents a different approach with special attention to the rheology of polymer solutions and flow conditions. Different approaches including Marrucci's approach in calculating stored elastic free energy (∆G E ) have been reviewed. Marrucci's equation is obtained based on a fundamental analysis of polymer chains microstructure. The new approach introduces the proper viscoelastic constitutive equations to estimate ∆G E . Selecting the appropriate rheological model is essential to correctly estimate the state of stress and deformation rates due to the flow. Moreover, the parameters of viscoelastic constitutive equations were defined, from the microstructural viewpoint, as functions of composition and temperature in semi-concentrated regions. Finally, flow induced change in the phase diagram of polymer solutions is predicted for a well-defined flow condition (constant shear rate and stress), and the results are compared with the previously reported experimental observations of mixing and demixing.

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“…[2,3] However, in the case of polymer blends, little work has been done. Horst and Wolf [6] modified the storage-energy term, accounting for disentanglements of polymer networks at high shear rate, and claimed qualitative agreement of their prediction with the experimental results of PS=poly(vinyl methyl ether) of Fernandez et al [7] Lyngaae-Jørgenson and Søndergaard [8,9] derived the stored energy by using polymer network theory and determined a critical stress required to induce mixing for a poly(methyl methacrylate)=poly(styrene-co-acrylonitrile) (PMMA=SAN) blend, while Kammar et al [10] introduced an interaction parameter to the stored energy and evaluated this parameter by fitting the model predictions to the experimental results of the PMMA=SAN blend.…”

Section: Introductionmentioning

confidence: 99%

Binary Miscible Blends of Poly(Methyl Methacrylate)/Poly(α-Methyl Styrene-co-Acrylonitrile). IV. Relationship Between Shear Flow and Viscoelastic Properties

Madbouly

2003

Journal of Macromolecular Science, Part B

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The effect of simple shear flow on the phase behavior of poly(methyle methacrylate), PMMA, and poly(a-methyl styrene-co-acrylonitrile), PaMSAN, exhibiting an LCST-type phase diagram, has been analyzed on the basis of a generalized Gibbs free energy of mixing, G g _ , modified by a stored energy term, E s . The value of the E s (the energy stored by the polymeric molecules during shear flow) was experimentally determined as a function of composition and shear rate from the viscoelastic material functions of the blend by using two different methods proposed by Marrucci and Wolf. The evaluated E s (proposed by Marrucci) from the entanglement plateau modulus, G 0 N , and dynamic shear viscosity at a given shear rate, Z(g _), were found to well describe the behavior of shear-induced mixing for the present system; i.e., a negative deviation of E s from the linear-mixing rule has been detected, which is a necessary condition for the elevation of the cloud points to higher values under shear flow. However, on the other hand, the calculated E s from the viscoelastic relaxation time, t 0 and zero shear viscosity, Z 0 (Wolf model), predicted both shear-induced mixing and shear-induced demixing for the large and small concentration range of PaMSAN, respectively; i.e., negative and positive deviation of E s from the linear-mixing rule was observed dependent on the concentration of PaMSAN. It is concluded that the viscoelastic material functions of the blend are very helpful for qualitatively anticipating the phase behavior of the blend under the effect of shear flow.

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Refined calculation of the phase separation behavior of sheared polymer blends: closed miscibility gaps within two ranges of shear rates

Cited by 42 publications

References 13 publications

Effect of shear flow on the phase‐separation behavior in a blend of polystyrene and polyvinyl methyl ether

Effect of shear flow on the phase‐separation behavior in a blend of polystyrene and polyvinyl methyl ether

Predicting flow induced change in phase diagram of polymer solutions in simple shear flow

Binary Miscible Blends of Poly(Methyl Methacrylate)/Poly(α-Methyl Styrene-co-Acrylonitrile). IV. Relationship Between Shear Flow and Viscoelastic Properties

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