Rheology and Entanglement Structure of Well-Entangled Polymer Melts: A Slip-Link Simulation Study
Rheology and Entanglement Structure of Well-Entangled Polymer Melts: A Slip-Link Simulation Study
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良好缠结聚合物熔体的流变学和缠结结构：滑移连接模拟研究
DOI：
10.1021/acs.macromol.9b00314
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发表时间：
2019
期刊：
影响因子：
5.5
通讯作者：
Takeshi Sato and Takashi Taniguchi
中科院分区：
文献类型：
--
作者：
Pierre Vidil;Keiichi Edamatsu;Vidil Pierre;Vidil Pierre;Takeshi Sato;Takeshi Sato and Takashi Taniguchi
我们扩展了最初由土井和泷本[Philos.Trans.R.1999]提出的滑动连杆模型。Soc.伦敦，A2003，361，641]来计算快速剪切和单轴拉伸流动。原始的Doi-Takimoto（DT）模型表明，当拉伸应变速率大于WiR（e）> 1时，稳态拉伸粘度增加，这在缠结聚合物熔体的实验中没有观察到。为了改进DT模型的预测，我们通过纳入Yaoita等人开发的拉伸/取向诱导的摩擦减少（SORF）[Macromolecules 2012，45，2773]扩展了DT模型。因此，我们可以成功地再现稀化行为稳定的单轴拉伸粘度的快速流动。通过使用解耦近似，我们已经发现，减少链拉伸有一个主要的影响减薄行为的应变率区域时，采用SORF。同时，在剪切流动下，可以观察到的SORF的效果在一个相对较高的应变速率区，在那里的聚合物链开始拉伸。此外，我们还研究了线性和非线性区域的DT模型的微观结构的统计特性。通过与通过原始链网络模型[Masubuchi等人，J. Chem. Phys.，2001，115，4387]，我们得出结论，从DT模型得到的微观结构的统计特性在应变率区域是合理的，但那些由DT模型得到的即使在应变率区域的SORF是可疑的，因为在DT模型中的缠结聚合物链的动力学在一个时间尺度短于Rouse弛豫时间被忽略.
We have extended the slip-link model originally developed by Doi and Takimoto [Philos. Trans. R. Soc. London, A2003,361, 641] to calculate fast shear and uniaxial elongational flows. The original Doi–Takimoto (DT) model shows that steady elongational viscosity increases when the elongational strain rate is larger than WiR(e)> 1, which is not observed in experiments for entangled polymer melts. To improve the predictions of the DT model, we have extended the DT model by incorporating the stretch/orientation-induced reduction of friction (SORF) developed by Yaoita et al. [Macromolecules2012,45, 2773]. Consequently, we can successfully reproduce thinning behavior in steady uniaxial elongational viscosities for fast flows. Through use of a decoupling approximation, we have found that the reduction of chain stretch has a major effect on the thinning behavior in the strain rate regionwhen employing SORF. Meanwhile, under shear flows, the effect of SORF can be observed in a relatively high strain rate region, where polymer chains start to stretch. Furthermore, we have investigated the statistical properties of the microscopic structure obtained from the DT model for both linear and nonlinear regions. From comparison with the results obtained by the primitive chain network model [Masubuchi et al.J. Chem. Phys.,2001,115, 4387], we have concluded that the statistical properties of the microscopic structure obtained from the DT model are plausible in the strain rate region, but those obtained by the DT model even with SORF in the strain rate regionare questionable because the dynamics of an entangled polymer chain in a time scale shorter than the Rouse relaxation time is ignored in the DT model.