Flow-Induced Phase Separation and Crystallization in Entangled Polyethylene Solutions under Elongational Flow,Macromolecules

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Flow-Induced Phase Separation and Crystallization in Entangled Polyethylene Solutions under Elongational Flow
Macromolecules ( IF 5.1 ) Pub Date : 2020-06-30 , DOI: 10.1021/acs.macromol.0c00508
Mohammad Hadi Nafar Sefiddashti ₁ , Brian J. Edwards ₁ , Bamin Khomami ₁

Affiliation

Flow-induced phenomena in entangled solutions of linear C₁₀₀₀H₂₀₀₂ polyethylene dissolved in n-hexadecane and benzene solvents were simulated via nonequilibrium molecular dynamics at concentrations of 14.5C* and 13.5C*, respectively, of the coil overlap concentration, C*. The simulations revealed that both solutions undergo a chemical phase separation when subject to planar extensional flow at extension rates faster than the inverse Rouse time of the solution. The onset of phase separation initiated after roughly two Hencky strain units of deformation for both solutions and attained a stationary state at about ten Hencky strain units. Furthermore, the simulations revealed that at very high extension rates the polymer phase forms semicrystalline domains regardless of the solvent; however, the critical extension rate for flow-induced crystallization appeared to be affected by a number of variables, including solution temperature and the chemical nature of the solvent.

中文翻译：

拉伸流在纠缠聚乙烯溶液中流致相分离和结晶

通过非平衡分子动力学模拟分别在线圈重叠浓度C为14.5 C *和13.5 C *的情况下，线性C ₁₀₀₀ H ₂₀₀₂聚乙烯在正十六烷和苯溶剂中的纠缠溶液中的流动诱导现象。*。模拟结果表明，两种溶液在经受平面延伸流时，其延伸速率都比溶液的反向Rouse时间快，因此会经历化学相分离。在两种溶液的大约两个Hencky应变单位变形后开始相分离，并在大约十个Hencky应变单位达到稳态。此外，模拟表明，在很高的延伸率下，聚合物相会形成半晶畴，而与溶剂无关。然而，流动诱导结晶的临界延伸速率似乎受到许多变量的影响，包括溶液温度和溶剂的化学性质。

更新日期：2020-08-11

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