Smirnova, Diana S. and Kornfield, Julia A. and Lohse, David J. (2011) Morphology Development in Model Polyethylene via Two-Dimensional Correlation Analysis. Macromolecules, 44 (17). pp. 6836-6848. ISSN 0024-9297 http://resolver.caltech.edu/CaltechAUTHORS:20110929-071111864
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Two-dimensional (2D) correlation analysis is applied to synchrotron X-ray scattering data to characterize morphological regimes during nonisothermal crystallization of a model ethylene copolymer (hydrogenated polybutadiene, HPBD). The 2D correlation patterns highlight relationships among multiple characteristics of structure evolution, particularly the extent to which separate features change simultaneously versus sequentially. By visualizing these relationships during cooling, evidence is obtained for two separate physical processes occurring in what is known as “irreversible crystallization” in random ethylene copolymers. Initial growth of primarily lamellae into unconstrained melt (“primary-irreversible crystallization”) is distinguished from subsequent secondary lamellae formation in the constrained, noncrystalline regions between the primary lamellae (“secondary-irreversible crystallization”). At successively lower temperatures (“reversible crystallization”), growth of the crystalline reflections is found to occur simultaneously with the change in shape of the amorphous halo, which is inconsistent with the formation of an additional phase. Rather, the synchronous character supports the view that growth of frustrated crystals distorts the adjacent noncrystalline material. Furthermore, heterocorrelation analysis of small-angle and wideangle X-ray scattering data from the reversible crystallization regime reveals that the size of new crystals is consistent with fringedmicellar structures (~9 nm). Thus, 2D correlation analysis provides new insights into morphology development in polymeric systems.
|Additional Information:||© 2011 American Chemical Society. Received: April 11, 2011 Revised: June 29, 2011. Publication Date (Web): August 15, 2011. We thank ExxonMobil Research and Engineering Company (Clinton, NJ) and funding from the National Science Foundation (DMR-0505393 and GOALI-0523083). We thank the beamline scientists at X27C at NSLS BNL (Dr. Lixia Rong and Jie Zhu). Important preliminary experiments were performed at 7.3.3 at ALS LBL with assistance from Dr. Alexander Hexemer and Eliot Gann, as well as Zuleikha Kurji (Caltech). We thank Maria Xenidou and Charles Symon for the synthesis of the polymer used in this study.|
|Official Citation:||Morphology Development in Model Polyethylene via Two-Dimensional Correlation Analysis Diana S. Smirnova, Julia A. Kornfield and ,David J. Lohse Macromolecules 2011 44 (17), 6836-6848|
|Usage Policy:||No commercial reproduction, distribution, display or performance rights in this work are provided.|
|Deposited By:||Ruth Sustaita|
|Deposited On:||29 Sep 2011 16:18|
|Last Modified:||26 Dec 2012 13:43|
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