Abstract

In this work, different weight contents of as-grown carbon nanofibers (CNFs), produced by chemical vapor deposition, were melt-extruded with polypropylene (PP) and their morphologic, structure and dielectric properties examined. The morphologic analysis reveals that the CNFs are randomly distributed in the form of agglomerates within the PP matrix, whereas the structural results depicted by Raman analysis suggest that the degree of disorder of the as-received CNFs was not affected in the PP/CNF composites. The AC conductivity of PP/CNF composites at room temperature evidenced an insulator–conductor transition in the vicinity of 2 wt.%, corresponding to a remarkable rise of the dielectric permittivity up to \(\sim \) 12 at 400 Hz, with respect to the neat PP (\(\sim \) 2.5). Accordingly, the AC conductivity and dielectric permittivity of PP/CNF 2 wt.% composites were evaluated by using power laws and discussed in the framework of the intercluster polarization model. Finally, the complex impedance and Nyquist plots of the PP/CNF composites are analyzed by using equivalent circuit models, consisting of a constant phase element (CPE). The analysis gathered in here aims at contributing to the better understanding of the enhanced dielectric properties of low-conducting polymer composites filled with carbon nanofibers.

Graphic abstract

中文翻译：

---

熔体挤出聚丙烯和碳纳米纤维复合材料的介电光谱

摘要

在这项工作中，通过化学气相沉积生产的不同重量含量的生长碳纳米纤维 (CNF) 与聚丙烯 (PP) 熔融挤出，并检查了它们的形态、结构和介电性能。形态分析表明，CNFs 以团聚体的形式随机分布在 PP 基质中，而拉曼分析所描绘的结构结果表明，在 PP/CNF 复合材料中，原样的 CNFs 的无序程度没有受到影响。PP/CNF 复合材料在室温下的 AC 电导率证明绝缘体 - 导体转变在 2 wt.% 附近，对应于在 400 Hz 时介电常数显着上升至\(\sim \) 12，相对于到整洁的 PP ( \(\sim \)2.5)。因此，PP/CNF 2 wt.% 复合材料的 AC 电导率和介电常数通过使用幂律进行评估，并在簇间极化模型的框架内进行讨论。最后，使用等效电路模型分析了 PP/CNF 复合材料的复阻抗和奈奎斯特图，该模型由恒定相位元件 (CPE) 组成。此处收集的分析旨在帮助更好地了解填充碳纳米纤维的低导电聚合物复合材料的介电性能增强。

图形摘要