Rheology and microrheology of a microstructured fluid: The gellan gum case
Rheology and microrheology of a microstructured fluid: The gellan gum case
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DOI：
10.1122/1.2751385
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发表时间：
2007-09-01
影响因子：
3.3
通讯作者：
Weitz, D. A.
中科院分区：
文献类型：
--
作者：
Caggioni, M.;Spicer, P. T.;Weitz, D. A.
采用颗粒跟踪微流变学方法研究了结冷胶与一价盐的凝胶化过程中恒定剪切力的作用。剪切修改结冷胶水凝胶的微观结构和系统的本体流变性质，这取决于是否在凝胶化过程中或之后施加剪切。微结构决定了凝胶的线性弹性响应，以及临界应变和应力，超过该临界应变和应力，响应变为非线性。使用整体振荡流变学来研究不同聚合物和盐浓度下的微结构结冷胶水凝胶。我们的系统和浓缩的微凝胶颗粒悬浮液之间的相似性可以通过考虑由微凝胶颗粒组成的微结构结冷胶系统来解释，所述微凝胶颗粒的尺寸由在凝胶化期间施加的剪切应力大小设定。聚合物浓度和离子强度控制单个微凝胶颗粒的弹性。我们还发现结冷胶体系在剪切时表现出从堵塞状态到非堵塞状态的等能转变，类似于堵塞的胶体体系[C。G. Robertson和X. R.王]，“粒子填充系统中的等能干扰跃迁”。
Particle tracking microrheology is used to study the effect of a constant applied shear during gelation of aqueous gellan gum with a monovalent salt. Shear modifies the gellan gum hydrogel microstructure and the bulk rheological properties of the system, depending on whether shear is applied during gelation or afterwards. The microstructure determines the linear elastic response of the gel, as well as the critical strain and stress above which the response becomes nonlinear. Bulk oscillatory rheology is used to study microstructured gellan gum hydrogels at different polymer and salt concentrations. The similarity between our system and concentrated microgel particle suspensions can be explained by considering the microstructured gellan system to be composed of microgel particles whose size is set by the applied shear stress magnitude during gelation. Polymer concentration and ionic strength control the individual microgel particles' elastic properties. We also find the gellan system exhibits an isoenergetic transition from the jammed to un-jammed state when sheared, similar to jammed colloidal systems [C. G. Robertson and X. R. Wang], "Isoenergetic jamming transition in particle-filled systems''.