Local Relaxation Behavior and Dynamic Fragility in Hydrogen Bonded Polymer Blends

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• 作者：Kevin A. Masser ; Hanqing Zhao ; Paul C. Painter ; James Runt
• 刊名：Macromolecules
• 出版年：2010
• 出版时间：November 9, 2010
• 年：2010
• 卷：43
• 期：21
• 页码：9004-9013
• 全文大小：1165K
• 年卷期：v.43,no.21(November 9, 2010)
• ISSN：1520-5835

文摘

The dynamics of intermolecularly hydrogen-bonded polymer blends of poly(p-(hexafluoro-2-hydroxyl-2-propyl)styrene) with poly(vinyl acetate), poly(ethylene[30]-co-vinyl acetate[70]) and poly(ethylene[55]-co-vinyl acetate[45]) are investigated by broadband dielectric relaxation spectroscopy and Fourier transform infrared spectroscopy. Each blend component exhibits a glassy state (β) relaxation, and these relaxations are affected by the formation of intermolecular associations. The glassy state behavior of the blends can be modeled using the Painter−Coleman association model. All blends exhibit a single T_g and a single dielectric segmental (α) relaxation, indicative of strong segmental-level coupling. The fragility of the glass-formers depends on the volume fraction of intermolecularly associated segments, and the association model predicts which compositions have the highest fragilities. A relaxation related to the breaking and reforming of hydrogen bonds is observed at temperatures above the α process, and its temperature dependence varies systematically with ethylene content.