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Phase Diagrams and Kinetics of Solid-Liquid Phase Transitions in Crystalline Polymer Blends

Matkar, Rushikesh Ashok
http://rave.ohiolink.edu/etdc/view?acc_num=akron1189533285

Abstract Details

2007, Doctor of Philosophy, University of Akron, Polymer Engineering.
A free energy functional has been formulated based on an order parameter approach to describe the competition between liquid-liquid phase separation and solid-liquid phase separation. In the free energy description, the assumption of complete solvent rejection from the crystalline phase that is inherent in the Flory diluent theory was removed as solvent has been found to reside in the crystalline phase in the form of intercalates. Using this approach,we have calculated various phase diagrams in binary blends of crystalline and amorphous polymers that show upper or lower critical solution temperature. Also, the discrepancy in the χ values obtained from different experimental methods reported in the literature for the polymer blend of poly(vinylidenefluoride) and poly(methylmethacrylate) has been discussed in the context of the present model. Experimental phase diagram for the polymer blend of poly(caprolactone) and polystyrene has also been calculated. Of particular importance is that the crystalline phase concentration as a function of temperature has been calculated using free energy minimization methods instead of assuming it to be pure. In the limit of complete immiscibility of the solvent in the crystalline phase, the Flory diluent theory is recovered. The model is extended to binary crystalline blends and the formation of eutectic, peritectic and azeotrope phase diagrams has been explained on the basis of departure from ideal solid solution behavior. Experimental eutectic phase diagram from literature of a binary blend of crystalline polymer poly(caprolactone) and trioxane were recalculated using the aforementioned approach. Furthermore, simulations on the spatio temporal dynamics of crystallization in blends of crystalline and amorphous polymers were carried out using the Ginzburg-Landau approach. These simulations have provided insight into the distribution of the amorphous polymer in the blends during the crystallization process. The simulated results are in close accordance with the experimentally observed concentration profiles of atactic polypropylene during the crystallization of isotactic polypropylene in a blend of these polymers. Finally described are the unique thermodynamics and kinetics that occur in thermoplastic elastomer blends of polypropylene and synthetic rubber, leading to the unique biphasic crystalline morphology imparting these blends with their characteristic high toughness and high impact strength. Phase diagrams in such blends exhibit a combined upper and lower critical solution temperature. These phase diagrams have been calculated based on the present model developed, and simulated results explain the structural development in these blends.
Thein Kyu (Advisor)
217 p.
polymer; blends; phase transitions; phase diagrams; crystallization; phase separation; phase field; thermodynamics; kinetics; thermoplastic; elastomer; concentration profiles; Flory diluent

Recommended Citations

Citations

  • Matkar, R. A. (2007). Phase Diagrams and Kinetics of Solid-Liquid Phase Transitions in Crystalline Polymer Blends [Doctoral dissertation, University of Akron]. OhioLINK Electronic Theses and Dissertations Center. http://rave.ohiolink.edu/etdc/view?acc_num=akron1189533285

    APA Style (7th edition)

  • Matkar, Rushikesh. Phase Diagrams and Kinetics of Solid-Liquid Phase Transitions in Crystalline Polymer Blends. 2007. University of Akron, Doctoral dissertation. OhioLINK Electronic Theses and Dissertations Center, http://rave.ohiolink.edu/etdc/view?acc_num=akron1189533285.

    MLA Style (8th edition)

  • Matkar, Rushikesh. "Phase Diagrams and Kinetics of Solid-Liquid Phase Transitions in Crystalline Polymer Blends." Doctoral dissertation, University of Akron, 2007. http://rave.ohiolink.edu/etdc/view?acc_num=akron1189533285

    Chicago Manual of Style (17th edition)

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© 2007, all rights reserved.
This open access ETD is published by University of Akron and OhioLINK.