The nonlinear rheology of a novel 3D hierarchical graphene polymer nanocomposites was investigated in this study. Based on an isotactic polypropylene, the nanocomposites were prepared using simple melt mixing, which is an industrially relevant and scalable technique. The novel nanocomposites stand out as having an electrical percolation threshold (≈0.94 wt%) comparable to solution mixing graphene-based polymer nanocomposites. Their nonlinear flow behavior was investigated in oscillatory shear via Fourier-transform (FT) rheology and Chebyshev polynomial decomposition. It was shown that in addition to an increase in the magnitude of nonlinearities with filler concentration, the electrical percolation threshold corresponds to a unique nonlinear rheological signature. Thus, in dynamic strain sweep tests, the nonlinearities are dependent on the applied angular frequency, potentially detecting the emergence of a weakly connected network that is being disrupted by the flow. This is valid for both the third relative higher harmonic from Fourier-transform rheology, I 3/1 , as well as the third relative viscous, v 3/1 , Chebyshev coefficient. The angular frequency dependency comprised non-quadratic scaling in I 3/1 with the applied strain amplitude and a sign change in v 3/1 . The development of the nonlinear signatures was monitored up to concentrations in the conductor region to reveal the influence of a more robust percolated network.

中文翻译：

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3D 分层石墨烯聚合物纳米复合材料渗透的非线性“奇数”

本研究研究了新型 3D 分层石墨烯聚合物纳米复合材料的非线性流变学。基于等规聚丙烯，纳米复合材料是使用简单的熔融混合制备的，这是一种工业相关且可扩展的技术。新型纳米复合材料具有与溶液混合石墨烯基聚合物纳米复合材料相当的电渗透阈值（≈0.94 wt%），因此脱颖而出。通过傅立叶变换 (FT) 流变学和切比雪夫多项式分解，在振荡剪切中研究了它们的非线性流动行为。结果表明，除了非线性程度随填料浓度增加外，电渗透阈值还对应于独特的非线性流变学特征。因此，在动态应变扫描测试中，非线性取决于应用的角频率，可能检测到被流动破坏的弱连接网络的出现。这对于傅立叶变换流变学的第三个相对高次谐波 I 3/1 以及第三个相对粘性 v 3/1 切比雪夫系数均有效。角频率相关性包括 I 3/1 的非二次缩放与施加的应变幅度和 v 3/1 的符号变化。监测非线性特征的发展直至导体区域的浓度，以揭示更强大的渗透网络的影响。以及第三个相对粘性，v 3/1 ，切比雪夫系数。角频率相关性包括 I 3/1 的非二次缩放与施加的应变幅度和 v 3/1 的符号变化。监测非线性特征的发展直至导体区域的浓度，以揭示更强大的渗透网络的影响。以及第三个相对粘性，v 3/1 ，切比雪夫系数。角频率相关性包括 I 3/1 的非二次缩放与施加的应变幅度和 v 3/1 的符号变化。监测非线性特征的发展直至导体区域的浓度，以揭示更强大的渗透网络的影响。