Abstract Adding high loadings of nanoparticles can remarkably alter the functionality of polymer nanocomposite foams. Therefore, this dramatic change was studied at the percolation threshold as a point to predict the properties of foamed nanocomposites using the viscoelastic characteristics of un-foamed ones. In this research, the effect of incorporating 10–40 wt% of ZnO nanoparticles on rheological properties of PS/ZnO samples was investigated. Then, these samples were foamed at processing temperatures of 80 and 120 °C to study morphology and electromagnetic properties. First, the rheological study showed that the storage modulus of nanocomposites increased significantly above 20 wt% of nanoparticles. A connected network of nanoparticles altered the microstructure of nanocomposite at this rheological percolation. The morphological results show a higher cell density for foamed samples above the rheological percolation. From electromagnetic properties, the effect of ZnO connected network is obvious on the absorption enhancement for 30 and 40 wt% and only for 40 wt% of ZnO at 80 and 120 °C, respectively. Therefore, the viscoelastic properties of samples are still dominant at the lower temperature, but the foam structure became more important at the higher temperatures. This shows that the role of the filler network faded at the higher temperature and electromagnetic properties were changed with the foam structure. The microstructure expansion results in the decrease of filler amount at a fixed volume of foams, so more filler fraction is required to form a connected network of nanoparticles.

中文翻译：

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纳米颗粒网络形成对微孔聚合物纳米复合泡沫电磁性能和泡孔形态的影响

摘要 添加高负载量的纳米粒子可以显着改变聚合物纳米复合泡沫的功能。因此，在渗透阈值处研究了这种显着变化，以此作为使用未发泡纳米复合材料的粘弹性特性来预测发泡纳米复合材料性能的一个点。在本研究中，研究了掺入 10-40 wt% 的 ZnO 纳米颗粒对 PS/ZnO 样品流变学性能的影响。然后，这些样品在 80 和 120 °C 的加工温度下发泡，以研究形态和电磁特性。首先，流变学研究表明，纳米复合材料的储能模量在超过 20 wt% 的纳米颗粒时显着增加。纳米颗粒的连接网络在这种流变渗透中改变了纳米复合材料的微观结构。形态学结果表明，高于流变渗透的泡沫样品具有更高的泡孔密度。从电磁特性来看，ZnO 连接网络对 30 wt% 和 40 wt% 的 ZnO 的吸收增强效果明显，仅对 40 wt% 的 ZnO 在 80 °C 和 120 °C 下的吸收增强效果明显。因此，样品的粘弹性在较低温度下仍然占主导地位，但泡沫结构在较高温度下变得更加重要。这表明填料网络的作用在较高温度下逐渐减弱，并且电磁性能随泡沫结构而变化。微观结构的膨胀导致泡沫体积固定时填料量的减少，因此需要更多的填料分数来形成纳米颗粒的连接网络。