Blanco-López Marcos, González-Garcinuño Álvaro, Tabernero Antonio, Martín Del Valle Eva M
Department of Chemical Engineering, University of Salamanca, Plaza los Caídos s/n, 37008 Salamanca, SA, Spain.
Instituto de Investigación Biomédica de Salamanca, Hospital Virgen de la Vega, Paseo San Vicente, 58-182, 37007 Salamanca, SA, Spain.
Polymers (Basel). 2021 Mar 22;13(6):966. doi: 10.3390/polym13060966.
The rheological behavior, in terms of steady and oscillatory shear flow, of Laponite with different polysaccharides (alginate, chitosan, xanthan gum and levan) in salt-free solutions was studied. Results showed that a higher polymer concentration increased the zero-rate viscosity and decreased the critical strain rate (Cross model fit) as well as increasing the elastic and viscous moduli. Those properties (zero-rate viscosity and critical strain rate) can be a suitable indicator of the effect of the Laponite on the shear flow behavior for the different solutions. Specifically, the effect of the Laponite predominates for solutions with large critical strain rate and low zero-rate viscosity, modifying significantly the previous parameters and even the yield stress (if existing). On the other hand, larger higher polymeric concentration hinders the formation of the platelet structure, and polymer entanglement becomes predominant. Furthermore, the addition of high concentrations of Laponite increases the elastic nature, but without modifying the typical mechanical spectra for polymeric solutions. Finally, Laponite was added to (previously crosslinked) gels of alginate and chitosan, obtaining different results depending on the material. These results highlight the possibility of predicting qualitatively the impact of the Laponite on different polymeric solutions depending on the solutions properties.
研究了无盐溶液中不同多糖（海藻酸盐、壳聚糖、黄原胶和果聚糖）与锂皂石在稳态和振荡剪切流方面的流变行为。结果表明，较高的聚合物浓度会增加零剪切速率粘度并降低临界应变速率（符合Cross模型），同时增加弹性模量和粘性模量。这些特性（零剪切速率粘度和临界应变速率）可以作为锂皂石对不同溶液剪切流行为影响的合适指标。具体而言，对于临界应变速率大且零剪切速率粘度低的溶液，锂皂石的影响占主导，会显著改变先前的参数甚至屈服应力（如果存在）。另一方面，较高的聚合物浓度会阻碍片状结构的形成，聚合物缠结变得占主导。此外，添加高浓度的锂皂石会增加弹性性质，但不会改变聚合物溶液的典型力学谱。最后，将锂皂石添加到（先前交联的）海藻酸盐和壳聚糖凝胶中，根据材料不同得到了不同结果。这些结果突出了根据溶液性质定性预测锂皂石对不同聚合物溶液影响的可能性。
