Abstract A model for explaining the effect of ionic strength on the yield stress and thixotropic behaviour of sodium montmorillonite or NaMt (SWy-2) gel was presented. NaMt gels displayed thixotropic behaviour at low to 0.1 M KCl concentration. This behaviour is reflected by an increasing yield stress with rest time after preshearing. The increasing yield stress measured the strengthing of the gel structure as it recovered at rest. The microstructure was formed by highly flexible nanosized platelets interacting both attractively via heterogeneous charge attraction in the edge-face and overlapping edge-edge configurations, and repulsively between the faces via electric double layer (EDL) force. This EDL force opened up the microstructure and was responsible for both the strength and thixotropic behaviour of the gel. The increasing gel strength with ionic strength up to 0.1 M KCl was a result of the weakening of the EDL force between the faces (interacting at an angle) particularly at the platelet bond forming the network junctions. The heterogeneous charge attraction forming the bond effectively increased in strength. In addition, weak platelet bonds were also able to form. The EDL force governs the microstructure development and this process takes a long time for every platelet to experience a minimum net force. The Leong model described the ageing or thixotropic behaviour quite well. At higher KCl concentrations, the van der Waals attractive force dominated the platelet-platelet interactions. These suspensions displayed time independent behaviour and was found to belong to the flocculated phase state.

中文翻译：

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钠蒙脱石 (SWy-2) 凝胶的胶体力、微观结构和触变性：静电和范德华力的作用

摘要 提出了一个解释离子强度对钠蒙脱石或NaMt (SWy-2) 凝胶屈服应力和触变行为影响的模型。NaMt 凝胶在低至 0.1 M KCl 浓度下显示出触变行为。这种行为反映在预剪切后随着静止时间增加的屈服应力。增加的屈服应力测量了凝胶结构在静止时恢复时的强度。微结构是由高度柔性的纳米片形成的，它们通过边缘面和重叠边缘配置中的异质电荷吸引力相互吸引，并通过双电层（EDL）力在面之间相互排斥。这种 EDL 力打开了微观结构，并决定了凝胶的强度和触变性。离子强度高达 0.1 M KCl 时凝胶强度增加是由于面之间的 EDL 力减弱（以一定角度相互作用），特别是在形成网络连接的片晶键处。形成键的异质电荷吸引力有效地增加了强度。此外，还能够形成弱的血小板键。EDL 力控制着微观结构的发展，这个过程需要很长时间才能让每个小板经历最小的净力。Leong 模型很好地描述了老化或触变行为。在较高的 KCl 浓度下，范德华吸引力主导了血小板-血小板相互作用。这些悬浮液表现出与时间无关的行为并且被发现属于絮凝相状态。1 M KCl 是由于面之间的 EDL 力减弱（以一定角度相互作用），特别是在形成网络连接的片晶键处。形成键的异质电荷吸引力有效地增加了强度。此外，还能够形成弱的血小板键。EDL 力控制着微观结构的发展，这个过程需要很长时间才能让每个小板经历最小的净力。Leong 模型很好地描述了老化或触变行为。在较高的 KCl 浓度下，范德华吸引力主导了血小板-血小板相互作用。这些悬浮液表现出与时间无关的行为并且被发现属于絮凝相状态。1 M KCl 是由于面之间的 EDL 力减弱（以一定角度相互作用），特别是在形成网络连接的片晶键处。形成键的异质电荷吸引力有效地增加了强度。此外，还能够形成弱的血小板键。EDL 力控制着微观结构的发展，这个过程需要很长时间才能让每个小板经历最小的净力。Leong 模型很好地描述了老化或触变行为。在较高的 KCl 浓度下，范德华吸引力主导了血小板-血小板相互作用。这些悬浮液表现出与时间无关的行为并且被发现属于絮凝相状态。