Toughening of Epoxies with Block Copolymer Micelles of Wormlike Morphology

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• 作者：Jia (Daniel) Liu ; Zachary J. Thompson ; Hung-Jue Sue ; Frank S. Bates ; Marc A. Hillmyer ; Marv Dettloff ; George Jacob ; Nikhil Verghese ; Ha Pham
• 刊名：Macromolecules
• 出版年：2010
• 出版时间：September 14, 2010
• 年：2010
• 卷：43
• 期：17
• 页码：7238-7243
• 全文大小：809K
• 年卷期：v.43,no.17(September 14, 2010)
• ISSN：1520-5835

文摘

An amphiphilic poly(ethylene-alt-propylene)-b-poly(ethylene oxide) (PEP-PEO) block copolymer (BCP) was blended with a bisphenol A-based epoxy resin formulation and self-assembled into a wormlike micelle structure. With an incorporation of 5 wt % of the BCP material, the fracture toughness was improved by >100% over the neat epoxy. The morphology and mechanical properties of this BCP-modified epoxy were investigated using transmission electron microscopy, dynamic mechanical analysis, tensile tests, and fracture toughness measurements. Toughening mechanisms from the wormlike micelle-modified material were investigated using the double-notch four-point-bending technique, and the results are compared with data obtained from the same epoxy thermoset formulation containing a BCP that self-assembled into spherical micelles. Elongated cylindrical micelles produce improved toughness, which is interpreted on the basis of a combination of mechanisms including crack tip blunting, cavitation, particle debonding, limited shear yielding, and crack bridging. The implications of the present study for polymer toughening in general are also discussed.