Linear and nonlinear shear flow behavior of monodisperse polyisoprene melts with a large range of molecular weights
Linear and nonlinear shear flow behavior of monodisperse polyisoprene melts with a large range of molecular weights
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DOI：
10.1122/1.2890780
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发表时间：
2008-05-01
影响因子：
3.3
通讯作者：
Fernyhough, Christine
中科院分区：
文献类型：
--
作者：
Auhl, Dietmar;Ramirez, Jorge;Fernyhough, Christine
本文使用线性和非线性测量结果报告了各种近单分散线性聚异戊二烯熔体的剪切流变数据。每条链的缠结数量范围为约 0.5 至 230。为了扩展可用频率和剪切速率的范围，在线性和非线性状态下改进和验证了时间-温度叠加程序。在线性流态中，与 Likhtman 和 McLeish [Macromolecules 35, 6332-6343 (2002)] 的管理论进行了详细比较。总体一致结果令人满意，但观察到并讨论了一些小的分歧，例如在交叉机制和稳态合规性方面。到目前为止，大多数缠结聚合物的非线性模型都是与解决方案的剪切数据进行比较。然而，溶液和熔体之间的等价性尚未明确。在本文中，将一系列非线性启动剪切实验的结果与管模型预测的结果进行了比较 [Graham 等人，J. Rheol。 47, 1117-1200 (2003)] 以及几个关于具有相似纠缠数量的纠缠解的文献数据集。发现熔体的行为与之前研究的溶液非常相似，并且与管理论非常吻合。当剪切速率超过一种缠结的劳斯时间时，以及对于缠结数量非常少的链来说，会观察到不一致。对于高分子量样品，在高应变下可能会出现不稳定性和边缘断裂，并根据这些影响对结果进行了讨论。这里提供的广泛数据集可以作为未来纠缠熔体理论和模型的测试。 (C) 2008 年流变学会。
Shear theological data for a wide range of nearly monodisperse linear polyisoprene melts are reported herein using the results of linear and nonlinear measurements. The number of entanglements per chain ranges from about 0.5 to 230. In order to extend the range of available frequencies and shear rates the procedure of time-temperature superposition is improved and validated in both the linear and the nonlinear regime. In the linear flow regime a detailed comparison with the tube theory by Likhtman and McLeish [Macromolecules 35, 6332-6343 (2002)] was performed. The overall agreement was found to be satisfactory but several minor disagreements, e.g., at the crossover regime and for the steady-state compliance, were observed and have been discussed. Until now, most nonlinear models for entangled polymers were compared with shear data on solutions. However, the equivalence between solutions and melts is not well established. In this paper the results of a series of nonlinear start-up shear experiments are compared with those predicted by the tube model [Graham et al., J. Rheol. 47, 1117-1200 (2003)] and with several literature datasets on entangled solutions having similar numbers of entanglements. The melts were found to behave in a very similar manner to the previously studied solutions and agree well with the tube theory. Disagreements are observed when the shear rate exceeds the Rouse time of one entanglement and also for chains with very small number of entanglements. For the high molecular weight samples possible instabilities and edge fracture can occur at high strains and the results are discussed in light of these effects. The extensive dataset presented here could serve as a test for future theories and models of entangled melts. (C) 2008 The Society of Rheology.