Viscosity of ring polymer melts.
Viscosity of ring polymer melts.
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DOI：
10.1021/mz400344e
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发表时间：
2013
影响因子：
7.015
通讯作者：
Vlassopoulos D
中科院分区：
文献类型：
--
作者：
Pasquino R;Vasilakopoulos TC;Jeong YC;Lee H;Rogers S;Sakellariou G;Allgaier J;Takano A;Brás AR;Chang T;Gooßen S;Pyckhout-Hintzen W;Wischnewski A;Hadjichristidis N;Richter D;Rubinstein M;Vlassopoulos D
我们测量了经过严格提纯的不同摩尔质量的环状聚异戊二烯、聚苯乙烯和聚氧化乙烯的线性流变性。讨论了线形聚合物熔体η0、η0与其对应的环0、环在等挠度条件下的零剪切粘度之比与缠结数Z的函数关系。在非纠缠区η0、线性/η0、环几乎不变，与先前的数据、原子模拟和理论预期η0、线性/η0、环=2一致。在纠缠区，环的粘度对Z的依赖性比线性聚合物弱得多，与标度理论和模拟的预测定性一致。从现有的实验数据中提取的幂定律在相当有限的范围1<；Z<；20，η0，线性/η0，环~Z1.2±0.3，弱于标度预测(η0，线性/η0，环~Z1.6±0.3)和模拟(η0，线性/η0，环~Z2.0±0.3)。然而，目前收集的最先进的实验数据毫不含糊地表明，环显示出一种明显背离其线性对应物的普遍趋势，因此它代表着朝着解决这个30年来的问题迈出的重要一步。
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 η0,linear to their ring counterparts η0,ring at isofrictional conditions is discussed as function of the number of entanglements Z. In the unentangled regime η0,linear/η0,ring is virtually constant, consistent with the earlier data, atomistic simulations, and the theoretical expectation η0,linear/η0,ring=2. In the entanglement regime, the Z-dependence of rings 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, η0,linear/η0,ring~ Z1.2±0.3, is weaker than the scaling prediction (η0,linear/η0,ring~ Z1.6±0.3) and the simulations (η0,linear/η0,ring~ Z2.0±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.