Effect of Pressure on Polymer Blend Miscibility:  A Temperature−Pressure Superposition

Rabeony, M.; Lohse, David J.; Garner, Richard T.; Han, Suh Joon; Graessley, William W.; Migler, Kalman D.

doi:10.1021/ma980723r

Cited by 46 publications

(63 citation statements)

References 15 publications

(36 reference statements)

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“…There is an interesting interplay between equation of state effects and the phase behavior. This has also a practical importance when a blend is mixed in an extruder or during injection molding of plastics 84) . In the framework of the bond fluctuation model the local fluid structure is mainly determined by athermal packing effects.…”

Section: Asymmetric Blendsmentioning

confidence: 99%

“…They found that the critical temperature increases approximately like N p for the range of chain length investigated. Moreover, recent experiments on polyolefin blends by Lohse and coworkers find evidence for a temperature-pressure superposition 84) : far from the UCST the pressure and density dependence of interaction energies is only a function of the density. However, deviations from this scaling are found for blends which demix upon heating.…”

Section: Asymmetric Blendsmentioning

confidence: 99%

See 1 more Smart Citation

Miscibility behavior and single chain properties in polymer blends: a bond fluctuation model study

Müller¹

1999

Macromol. Theory Simul.

106

113

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SUMMARY: Computer simulation studies on the miscibility behavior and single chain properties in binary polymer blends are reviewed. We consider blends of various architectures in order to identify important architectural parameters on a coarse grained level and study their qualitative consequences for the miscibility behavior. The phase diagram, the relation between the exchange chemical potential and the composition, and the intermolecular pair correlation functions for symmetric blends of linear chains, blends of cyclic polymers, blends with an asymmetry in cohesive energies, blends with different chain lengths, blends with distinct monomer shapes, and blends with a stiffness disparity between the components are discussed. For strictly symmetric blends the Flory-Huggins theory becomes quantitatively correct in the long chain length limit, when the v parameter is identified via the intermolecular pair correlation function. For small chain lengths composition fluctuations are important. They manifest themselves in 3D Ising behavior at the critical point and an upward parabolic curvature of the v parameter from small-angle neutron scattering close to the critical point. The ratio between the mean field estimate and the true critical temperature decreases like v p aqb 3 for long chain lengths. The chain conformations in the minority phase of a symmetric blend shrink as to reduce the number of energeticaly unfavorable interactions. Scaling arguments, detailed self-consistent field calculations and Monte Carlo simulations of chains with up to 512 effective segments agree that the conformational changes decrease around the critical point like 1a N p . Other mechanisms for a composition dependence of the single chain conformations in asymmetric blends are discussed. If the constituents of the blends have non-additive monomer shapes, one has a large positive chain-length-independent entropic contribution to the v parameter. In this case the blend phase separates upon heating at a lower critical solution temperature. Upon increasing the chain length the critical temperature approaches a finite value from above. For blends with a stiffness disparity an entropic contribution of the v parameter of the order 10 -3 is measured with high accuracy. Also the enthalpic contribution increases, because a back folding of the stiffer component is suppressed and the stiffer chains possess more intermolecular contacts. Two aspects of the single chain dynamics in blends are discussed: (a) The dynamics of short non-entangled chains in a binary blend are studied via dynamic Monte Carlo simulations. There is hardly any coupling between the chain dynamics and the thermodynamic state of the mixture. Above the critical temperatures both the translational diffusion and the relaxation of the chain conformations are independent of the temperature. (b) Irreversible reactions of a small fraction of reactive polymers at a strongly segregated interface in a symmetric binary polymer blend are investigated. End-functionalized homopolymers of different...

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Section: Asymmetric Blendsmentioning

confidence: 99%

Section: Asymmetric Blendsmentioning

confidence: 99%

Miscibility behavior and single chain properties in polymer blends: a bond fluctuation model study

Müller¹

1999

Macromol. Theory Simul.

106

113

View full text Add to dashboard Cite

show abstract

“…2, "Thermodynamics of Polymer Blends"), the miscibility of polymer blends depends on the balance of small enthalpic and/or non-configurational entropic effects. Sensitivity of this balance to small variation of the macromolecular structure is illustrated in the series of papers on miscibility of model polyolefins -e.g., see (Rabeony et al 1998). Another example is provided by the photoisomerization initiated, reversible phase separation of PVME blends with stilbene-substituted PS (Ohta et al 1998).…”

Section: Compatibilizationmentioning

confidence: 96%

Polymer Blends: Introduction

Utracki

Mukhopadhyay²,

Gupta

2014

Polymer Blends Handbook

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“…The role of pressure on the phase diagram of polymer liquids and also polymer mixtures has been intensely studied in the past decades, and there has been increased interest in the effects of pressure on the miscibility of polymers An & wolf, 1998;Geerissen et al 1985;Hammouda & Bauer, 1995;Hosokawa et al 1993;Lefebvre et al 2000;Maderek et al 1983;Rabeony et al 1998;Wolf & Jend, 1977,1978. One reason is the need for such data to more fully understand polymer miscibility in relation to the various proposed theories and equations of state.…”

Section: Introductionmentioning

confidence: 99%