Abstract
The shear rheology of a binary polymer blend exhibiting a lower critical solution temperature (LCST) phase diagram and a small dynamic asymmetry (difference of glass transition temperatures between its constituents) has been investigated in the vicinity of phase separation; it is a mixture of a random copolymer of styrene and maleic anhydrite and poly(methyl methacrylate). In the linear viscoelastic regime, the material functions are sensitive to phase separation, and the effects of critical concentration fluctuations, which dominate the mechanical response, are quantified, yielding both the binodal and spinodal curves. The weak dynamic asymmetry is apparently responsible for the reduced magnitude of the observed effects, compared to blends exhibiting much larger contrast in glass transition; therefore, this property affects to some degree the accuracy of the rheologically determined phase diagram. The steady shear properties are weakly sensitive to phase separation, and suggest that shear-induced demixing may be possible. They also indicate the importance of the amount of strain energy introduced to the blend in controlling the effects of flow on phase behavior.
This investigation demonstrates that the universal effects of concentration fluctuations can be detected in LCST binary polymer blends, provided that some dynamic asymmetry exists, and further they can be quantified in order to characterize the interplay between rheology and thermodynamics of these systems.
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References
Aelmans NJJ, Reid VMC (1996) Shear-induced (de)mixing of SMA/PMMA blends at high shear rates. Proceedings of the Fifth European Symposium on Polymer Blends. Maastrict, The Netherlands
Ajji A, Choplin L (1991) Rheology and dynamics near phase separation in a polymer blend: model and scaling analysis. Macromolecules 24:5221–5222
Ajji A, Choplin L, Prud'homme RE (1988) Rheology and phase separation in polystyrene/poly(vinyl methyl ether) blends. J Polym Sci: Part B: Polym Phys 26:2279–2289
Ajji A, Choplin L, Prud'homme RE (1991) Rheology of polystyrene/poly(vinyl methyl ether) blends near the phase transition. J Polym Sci: Part B: Polym Phys 29:1573–1578
Brannock GR, Barlow JW, Paul DR (1991) Blends of styrene/maleic anhydrite copolymers with polymethacrylates. J Polym Sci: Part B: Polym Phys 29:413–429
Chen ZJ, Wu RJ, Shaw MT, Weiss RA, Fernandez ML, Higgins JS (1995) Rheo-optical behavior of binary polymer blends: the effect of simple shear flow on phase behavior. Polym Eng Sci 35:92–99
Colby RH (1989) Breakdown of the time temperature superposition in miscible polymer blends. Polymer 30:1275–1278
De Gennes PG (1979) Scaling concepts in polymer physics. Cornell University Press, New York
Fernandez ML, Higgins JS, Horst R, Wolf BA (1995) Complex miscibility behaviour for polymer blends in flow. Polymer 36:149–154
Ferry JD (1980) Viscoelastic properties of polymers, 3rd edn. Wiley, New York
Fredrickson GH, Larson RG (1987) Viscoelasticity of homogeneous polymer melts near a critical point. J Chem Phys 86: 1553–1560
Han CD (1981) Multiphase flow in polymer processing. Academic Press, New York
Han JH, Choi-Feng C, Li DJ, Han CD (1995) Effect of flow geometry on the theology of dispersed two-phase blends of polystyrene and poly(methyl methacrylate). Polymer 36:2451–2462
Horst R, Wolf BA (1993) Refined calculation of the phase separation behavior of sheared polymer blends: closed miscibility gaps between two ranges of shear rates. Macromolecules 26:5676–5680
Horst R, Wolf BA (1994) Calculation of shear influences on the phase separation of polymer blends exhibiting upper critical solution temperatures. Rheol Acta 33:99–107
Kapnistos M, Hinrichs A, Vlassopoulos D, Anastasiadis SH, Stammer A, Wolf BA (1996a) Rheology of a lower critical solution temperature binary polymer blend in the homogeneous, phase separated and transitional regimes. Macromolecules, in press
Kapnistos M, Vlassopoulos D, Anastasiadis SH (1996b) Determination of both the binodal and spinodal curves in polymer blends by shear rheology. Europhys Lett 34:513–518
Kitade S, Takahashi Y, Noda I (1994) Viscoelastic properties of homogeneous polymer blends in the terminal region. Macromolecules 27:7397–7401
Larson RG (1988) Constitutive equations for polymer melts and solutions. Butterworths, Boston
Larson RG (1992) Flow-induced mixing, demixing and phase transition in polymeric fluids. Rheol Acta 31:497–520
Läuger J, Lay R, Maas S, Gronski W (1995) Structure development of a polybutadiene/polyisoprene blend during spinodal decomposition. Comparison between light scattering and optical microscopy. Macromolecules 28:7010–7015
Manda D, Higgins JS (1996) unpublished results
Mani S, Malone MF, Winter HH (1992a) Influence of phase separation on the linear viscoelastic behavior of a miscible polymer blend. J Rheol 36:1625–1649
Mani S, Malone MF, Winter HH (1992b) Shear-induced demixing in a polystyrene/poly(vinyl methyl ether) blend: in situ fluorescence and rheometry. Macromolecules 25:5671–5676
Mani S, Malone MIT, Winter HH, Halary JL, Monnerie L (1991) Effects of shear on miscible polymer blends: in situ fluorescence studies. Macromolecules 24:5451–5458
Mazich KA, Carr SH (1983) The effect of flow on the miscibility of a polymer blend. J Appl Phys 54:5511–5514
Min K, White JL, Fetters LJ (1984) High density polyethylene/polystyrene blends: phase distribution, morphology, rheological measurements, extrusion and melt spinning behavior. J Appl Polym Sci 29:2117–2142
Nakatani AI, Kim H, Takahashi Y, Matsushita Y, Takano A, Bauer BJ, Han CC (1990) Shear stabilization of critical fluctuations in bulk polymer blends studied by small angle neutron scattering. J Chem Phys 93:795–810
Nesarikar AR (1995) Rheology of polymer blend liquid-liquid phase separation. Macromolecules 28:7202–7207
Rosedale JH, Bates FS (1990) Rheology of ordered and disordered symmetric poly(ethylene propylene)-poly(ethylethylene) diblock copolymers. Macromolecules 23:2329–2338
Stadler R, deLucca Freitas L, Krieger V, Klotz S (1988) Influence of the phase separation on the linear viscoelastic properties of a polystyrene-poly(vinyl methyl ether) blend. Polymer 29:1643–1647
Takahashi Y, Suzuki H, Nakagawa Y, Noda I (1994a) Effects of shear flow on viscoelastic properties of polystyrene/poly(vinyl methyl ether) blends near the phase separation temperature. Macromolecules 27:6476–6481
Takahashi Y, Suzuki H, Nakagawa Y, Noda I (1994b) Viscoelastic properties of polystyrene-poly(vinyl methyl ether) blends in oscillatory and steady shear flows near the phase separation temperature. Polym Intl 34:327–331
Tanaka H (1996) Universality of viscoelastic phase separation in dynamically asymmetric fluid mixtures. Phys Rev Lett 76:787–790
Wu R, Shaw MT, Weiss RA (1992) Rheo-optical studies of stress-induced phase changes in blends exhibiting UCST: polystyrene and polyisobutylene. J Rheol 36:1605–1623
Zawada JA, Fuller GG, Colby RH, Fetters LJ, Roovers J (1994) Measuring component contributions to the dynamic modulus in miscible polymer blends. Macromolecules 27:6851–6860
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Dedicated to the memory of Professor Tasos C. Papanastasiou
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Vlassopoulos, D. Rheology of critical LCST polymer blends: poly(styrene-co-maleic anhydrite)/poly(methyl methacrylate). Rheola Acta 35, 556–566 (1996). https://doi.org/10.1007/BF00396507
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DOI: https://doi.org/10.1007/BF00396507