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Compositional Dependence of Segmental Dynamics in a Miscible Polymer Blend

Chung, G.-C. and Kornfield, J. A. and Smith, S. D. (1994) Compositional Dependence of Segmental Dynamics in a Miscible Polymer Blend. Macromolecules, 27 (20). pp. 5729-5741. ISSN 0024-9297.

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The segmental motion of each species in polyisoprene/poly(vinylethylene) (PI/PVE) miscible blends is studied at three different compositions using two-dimensional deuteron exchange NMR (2D ^2H NMR). The individual species exhibit widely different mean mobilities and broad mobility distributions near the glass transition of each blend. As the PVE content increases, both the difference in mean mobilities between the two species and the width of the mobility distribution for both components increase. The change in these two types of dynamic heterogeneity with PVE content appears to produce the anomalous broadening of the glass transition. The mean reorientational correlation times of each component can differ by 2 orders of magnitude under identical conditions. This difference can be described in terms of distinct effective glass transition temperatures, T_g*, for the two species. The separation between the two effective glass transition temperatures increases almost monotonically with PVE content, consistent with the more pronounced thermorheological complexity of blends rich in PVE. The individual T_g*'s also exhibit a different compositional dependence from that of the calorimetric T_g of the blend observed by differential scanning calorimetry (DSC). This behavior can give rise to the complex compositional dependence of individual mobilities, apparent when the mobilities are compared at the same T - T_g with respect to the DSC T_g of the blend.

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Kornfield, J. A.0000-0001-6746-8634
Additional Information:© 1994 American Chemical Society. Received May 19, 1994. We gratefully acknowledge the support of the National Science Foundation Presidential Young Investigator Award (J.A.K.), Chevron, the Caltech Consortium in Chemistry and Chemical Engineering, du Pont de Nemours, Eastman Kodak, and the Petroleum Research Fund, administered by the American Chemical Society.
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Chevron CorporationUNSPECIFIED
Caltech Consortium in Chemistry and Chemical EngineeringUNSPECIFIED
E. I. DuPont de Nemours and Company, Inc.UNSPECIFIED
Eastman Kodak CompanyUNSPECIFIED
American Chemical Society Petroleum Research FundUNSPECIFIED
Issue or Number:20
Record Number:CaltechAUTHORS:20180601-160702859
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Official Citation:Compositional Dependence of Segmental Dynamics in a Miscible Polymer Blend G.-C. Chung, J. A. Kornfield, and S. D. Smith Macromolecules 1994 27 (20), 5729-5741 DOI: 10.1021/ma00098a030
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:86764
Deposited By: George Porter
Deposited On:01 Jun 2018 23:36
Last Modified:03 Oct 2019 19:48

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