Viscosity of Ring Polymer Melts

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• 作者：Rossana Pasquino ; Thodoris C. Vasilakopoulos ; Youn Cheol Jeong ; Hyojoon Lee ; Simon Rogers ; George Sakellariou ; J眉rgen Allgaier ; Atsushi Takano ; Ana R. Br谩s ; Taihyun Chang ; Sebastian Goo脽en ; Wim Pyckhout-Hintzen ; Andreas Wischnewski ; Nikos Hadjichristidis ; Dieter Richter ; Michael Rubinstein ; Dimitris Vlassopoulos
• 刊名：ACS Macro Letters
• 出版年：2013
• 出版时间：October 15, 2013
• 年：2013
• 卷：2
• 期：10
• 页码：874-878
• 全文大小：233K
• 年卷期：v.2,no.10(October 15, 2013)
• ISSN：2161-1653

文摘

We have measured the linear rheology of critically purified ring polyisoprenes, polystyrenes, and polyethyleneoxides of different molar masses. The ratio of the zero-shear viscosities of linear polymer melts 畏_0,linear to their ring counterparts 畏_0,ring at isofrictional conditions is discussed as a function of the number of entanglements Z. In the unentangled regime 畏_0,linear/畏_0,ring is virtually constant, consistent with the earlier data, atomistic simulations, and the theoretical expectation 畏_0,linear/畏_0,ring = 2. In the entanglement regime, the Z-dependence of ring viscosity is much weaker than that of linear polymers, in qualitative agreement with predictions from scaling theory and simulations. The power-law extracted from the available experimental data in the rather limited range 1 < Z < 20, 畏_0,linear/畏_0,ring Z^1.2卤0.3, is weaker than the scaling prediction (畏_0,linear/畏_0,ring Z^1.6卤0.3) and the simulations (畏_0,linear/畏_0,ring Z^2.0卤0.3). Nevertheless, the present collection of state-of-the-art experimental data unambiguously demonstrates that rings exhibit a universal trend clearly departing from that of their linear counterparts, and hence it represents a major step toward resolving a 30-year-old problem.