Li Jian, Li Yaning, Xiao Wei, Wang Jingyan, Wang Boliang
School of Chemistry and Chemical Engineering, Nanjing University of Science and Technology, Nanjing 210094, China.
Chongqing Hongyu Precision Industrial Group Co., Ltd., Chongqing 402760, China.
Gels. 2023 Nov 15;9(11):902. doi: 10.3390/gels9110902.
Investigating the structural evolution of particulate gels is a very challenging task due to their vulnerability and true flow characteristics. In this work, deeper insight into the rheological properties of gel fuels filled with fumed silica (FS) and aluminum microparticles (Al MPs) was gained by changing shear procedures. Firstly, the flow curves were found to no longer follow the monotonic power law and exhibited subtle thixotropic responses. As the shear rate increased, the gel structure underwent a transition from local shear to bulk shear in the nonlinear region after yielding. This finding reveals the prevalence of nonideal local shear in industry. Secondly, the time-dependent rheological responses demonstrated that the strength spectrum of gel fuels depends on the applied shear rate, with stress relaxation more easily observed at lower shear rates. Those results involved the structural disruption, recovery, and equilibrium of particulate gels from two scales of shear rate and shear time.
由于颗粒凝胶的脆弱性和真实流动特性，研究其结构演变是一项极具挑战性的任务。在这项工作中，通过改变剪切程序，对填充有气相二氧化硅（FS）和铝微粒（Al MPs）的凝胶燃料的流变特性有了更深入的了解。首先，发现流动曲线不再遵循单调幂律，并表现出微妙的触变响应。随着剪切速率的增加，凝胶结构在屈服后的非线性区域经历了从局部剪切到整体剪切的转变。这一发现揭示了工业中非理想局部剪切的普遍性。其次，随时间变化的流变响应表明，凝胶燃料的强度谱取决于所施加的剪切速率，在较低剪切速率下更容易观察到应力松弛。这些结果涉及颗粒凝胶在剪切速率和剪切时间两个尺度上的结构破坏、恢复和平衡。
