标题： 强导电性复杂流体的同步流变电动测量 显示英文标题

标题： Simultaneous rheo-electric measurements of strongly conductive complex fluids

摘要： 我们引入了一种新颖的装置，用于应力控制流变仪，在剪切下对强导电复杂流体进行同时的流变和电测量。通过使用一种无毒的室温液态金属，完成了旋转轴的电连接，且附加机械摩擦最小，从而实现了低至1帕的同步应力测量。我们利用该设计的能力，对由吸引性炭黑颗粒制成的凝胶进行了广泛的流变-电实验，其浓度范围从4%到15%重量比。 首先，不同剪切历史制备的静止凝胶实验显示，弹性模量$G'_0$与凝胶的电导率$\sigma_0$之间存在稳健的幂律标度关系，即$G'_0 \sim \sigma_0^\alpha$，其中$\alpha =1.65 \pm 0.04$与凝胶浓度无关。 其次，同时进行的蠕变实验的电导率测量首次揭示了在实验早期阶段，当剪切速率随时间弱幂律下降时，体相中发生了塑性事件。 随后电导率和剪切速率的演变使我们提出了一个局部屈服场景，该场景与之前的测速测量结果一致。 最后，我们确定了炭黑凝胶的本构流变和电行为。首先为机械测量引入的修正被仔细扩展到电测量，以准确区分电导率的体相和表面贡献。 作为一个示例，我们研究了五种不同等级的炭黑凝胶的本构流变-电特性，并展示了新型流变-电装置作为强导电复杂流体及其应用的多功能表征工具的相关性。 显示英文摘要

摘要： We introduce a novel apparatus designed for stress-controlled rheometers to perform simultaneous rheological and electrical measurements on strongly conductive complex fluids under shear. By means of a non-toxic liquid metal at room temperature, the electrical connection to the rotating shaft is completed with minimal additional mechanical friction, allowing for simultaneous stress measurements as low as 1 Pa. We use the capabilities of this design to perform an extensive set of rheo-electric experiments on gels formulated from attractive carbon black particles, at concentrations ranging from 4 to 15% wt. First, experiments on gels at rest prepared with different shear history show a robust power-law scaling between the elastic modulus $G'_0$ and the conductivity $\sigma_0$ of the gels, i.e. $G'_0 \sim \sigma_0^\alpha$, with $\alpha =1.65 \pm 0.04$ independently of the gel concentration. Second, conductivity measurements performed simultaneously with creep experiments reveal for the first time that plastic events take place in the bulk while the shear rate decreases as a weak power law of time in the early stage of the experiment. The subsequent evolution of the conductivity and shear rate allows us to propose a local yielding scenario that is in agreement with previous velocimetry measurements. Finally, we determine the constitutive rheological and electrical behavior of carbon black gels. Corrections first introduced for mechanical measurements are carefully extended to electrical measurements to accurately distinguish between bulk and surface contributions to the conductivity. As an illustrative example, we examine the constitutive rheo-electric properties of five carbon black gels of different grades, and demonstrate the relevance of the novel rheo-electric apparatus as a versatile characterization tool for strongly conductive complex fluids and their applications.