Strength of polymer phase boundaries with large interfacial width: Effects of interfacial profile and phase separation morphology |
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Authors: | Chun‐Jie Chang Yi‐Huan Lee Chi‐Ju Chiang Yu‐Ping Lee Hao‐Ching Chien Wen‐Pin Shih Yao‐Yi Cheng Chi‐An Dai Chia‐Hwa Chang |
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Affiliation: | 1. Institute of Polymer Science and Engineering, National Taiwan University, Taipei, 106 Taiwan;2. Department of Chemical Engineering, National Taiwan University, Taipei, 106 Taiwan;3. Department of Mechanical Engineering, National Taiwan University, Taipei, 106 Taiwan;4. Institute of Organic and Polymeric Materials, National Taipei University of Technology, Taipei, 106 Taiwan;5. RDD LAB, Incorporated Taipei, 110 Taiwan |
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Abstract: | In this study, we investigate the effect of random copolymer additives on the interfacial profile, the lateral phase separation morphology, and the interfacial fracture toughness (Gc) between two immiscible polymers. The interface between polystyrene (PS)/poly(methyl methacrylate) (PMMA) was reinforced with a random copolymer mixture when two or more PSf ‐r‐PMMA1‐f random copolymers with different volume fraction, f, were blended. For short annealing time (<3 h), the random copolymer mixture exhibits a disordered and large domain structure (>1 lm) from which crazes can be extensively initiated and developed, leading to a large interfacial fracture energy. With increasing annealing time, the random copolymer mixture self‐organizes as multiple layers, with the composition that changes gradually from PS‐rich layers to PMMA‐rich layers across the interface, leading to a large interfacial width. However, within each layer, the random copolymer mixture microphase separates laterally into smaller domains (<200 nm). We found that the microphase‐separated domains with nanometer‐sized structure significantly affect the stability of craze fibrils that can be initiated and widened at the interface, leading to a decrease in the fracture energy. © 2010 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 48: 1834–1846, 2010 |
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Keywords: | adhesion atomic force microscopy (AFM) crazing interfacial morphology microphase separation |
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