Miscibility phase separation

Polymers dynamics of polymer chains microviscosity free volume orientation of chains in stretched samples miscibility phase separation diffusion of species through polymer networks end-to-end macrocyclization dynamics monitoring of polymerization degradation... 

Solid state NMR offers powerful tools for probing miscibility, phase separated structure and molecular motion in polymer blends and which may be beyond the resolution limits of conventional microscopic or thermal analysis. A large number of NMR works have been published and some of them were reviewed. In this review, therefore, we introduce recent research works on polymer blends by solid state NMR and focus on the miscibility and phase separation of polymer blends that are responsible for the improvement in their physical properties. 

The dependence of excitation transport on local chromophore concentration has been used to provide qualitative information on the characteristics of polymers in blends. Excimer fluorescence resulting from excitation transport has been employed to characterize polymer miscibility, phase separation and the kinetics of spinodal decomposition (1-31. Qualitative characterization of phase separation in blends (4.51 and the degree of chain entanglement as a function of sample preparation and history (6.71 has also been investigated through transport with trapping experiments. In these experiments one polymer in the blend contains donor chromophores and the second contains acceptors. Selective excitation of the former and detection of the latter provides a qualitative measure of interpenetration of the two components. 

When the polymer components in a blend are less miscible, phase separation will form larger domains with weaker interfacial bonding between them. The interfaces will therefore fail under stress and properties of polyblends are thus likely to be poorer than for either of the polymers in the blend. U-shaped property curves (Figure 4.40c) thus provide a strong indication of immiscibility. In most cases they also signify practical incompatibility, and hence lack of practical utility. 

Z. Bayraktar and E. Kiran, Miscibility, phase separation and volumetric properties of solutions of poly(dimethylsiloxane) in supercritical carbon dioxide, J. Appl. Polym. Set, 75, 1397-1403 (2000). 

In the case of small plasticizers, the considered molecules need to be miscible, i.e. to present strong intermolecular forces with the polymer. In the case of partial miscibility, phase separation occurs when the miscibility limit of the plasticizer is exceeded and pure plasticizer phase and enriched... 

The following chapters in this book provide a comprehensive overview on the miscibility, phase separation, morphology and other fundamental properties of... 

KIR Kiran, E., Hassler, J.C., and Srivastava, R., Miscibility, phase separation, and phase settlement dynamics in solutions of ethylene-propylene-diene monomer elastomer in propane -i- n-octane binary fluid mixtures at high pressures, Ind. Eng. Chem. Res., 52, 1806, 2013. 

Sonja Krause, obtained her Ph.D. in Physical Chemistry at the University of California at Berkeley in 1957. She worked as a Senior Physical Chemist at the Rohm and Haas Company until 1964 when she joined the U.S. Peace Corps, teaching for two years in Universities in Nigeria and Ethiopia. She then taught for one year at the University of Southern California in Los Angeles and has been at Rensselaer Polytechnic Institute, presently as Professor of Physical Chemistry, since 1967. Her research interests include polymer-polymer miscibility, phase-separated polymer systems, small-angle scattering, and transient electric birefringence of macromolecules in solution. 

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