Rubio Manuel, Ponce-Torres Alberto, Vega Emilio José, Montanero José María
Depto. de Ingeniería Mecánica, Energética y de los Materiales and Instituto de Computación Científica Avanzada (ICCAEx), Universidad de Extremadura, E-06006 Badajoz, Spain.
Materials (Basel). 2020 Jan 2;13(1):192. doi: 10.3390/ma13010192.
We study with ultra-high-speed imaging the thinning of the filament formed during the breakup of a pendant droplet of very weakly viscoelastic polymer solutions of polyvinylpyrrolidone (PVP) and polyethylene oxide (PEO). In the latter case, we consider two molecular weights: 10 5 g/mol (PEO100K) and 2 × 10 6 g/mol (PEO2M). The results allow us to measure with high reproducibility extensional relaxation times of the order of 10 μ s. Despite the noticeable differences between PVP and PEO100K, very similar values are obtained for the range of concentrations where the linear elasto-capillary is established. For PEO2M, the extensional relaxation time depends on the concentration even for values significantly smaller than the overlap one. The prediction c low for the concentration below which the linear elasto-capillary regime cannot be reached qualitatively agrees with the results for PVP and PEO2M, while it underestimates the critical concentration for PEO100K. The results for PEO2M are consistent with those reported in the literature for higher concentrations.
我们使用超高速成像技术研究了聚乙烯吡咯烷酮（PVP）和聚环氧乙烷（PEO）的极弱粘弹性聚合物溶液悬垂液滴破裂过程中形成的细丝的变细情况。对于后者，我们考虑了两种分子量：10⁵ g/mol（PEO100K）和2×10⁶ g/mol（PEO2M）。结果使我们能够以高重现性测量出约10微秒量级的拉伸松弛时间。尽管PVP和PEO100K之间存在显著差异，但在建立线性弹性毛细管作用的浓度范围内，得到了非常相似的值。对于PEO2M，即使在远小于重叠浓度的值时，拉伸松弛时间也取决于浓度。对于低于该浓度则无法定性地达到线性弹性毛细管状态的预测浓度clow，与PVP和PEO2M的结果定性相符，但低估了PEO100K的临界浓度。PEO2M的结果与文献中报道的较高浓度时的结果一致。
