Abstract The insulator-conductor percolative composites have been mostly constructed to achieve high permittivity and negative permittivity. In this work, permittivity transition from positive to negative is investigated in acrylic polyurethane-aluminum (APu/Al) percolative composites at radio frequency. Both the high permittivity and negative permittivity are accompanied with low loss due to the self-passivated nature of aluminum. The reactance and ac conductivity are studied to explain the dielectric properties, which provides an essential insight into the universal principles of high permittivity and negative permittivity behaviors in percolative composites. Meanwhile, when the conductive filler content exceeds the percolation threshold, a derived formula of permittivity has been put forward on the basis of the existing theoretical framework of percolation theory. Resourceful dielectric properties of APu/Al percolative composites will make them as potential alternatives for capacitors and metamaterials.

中文翻译：

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丙烯酸聚氨酯-铝复合材料中介电常数从正到负的转变

摘要 绝缘体-导体渗透复合材料主要用于实现高介电常数和负介电常数。在这项工作中，研究了丙烯酸聚氨酯-铝 (APu/Al) 渗流复合材料在射频下从正到负的介电常数转变。由于铝的自钝化性质，高介电常数和负介电常数都伴随着低损耗。研究电抗和交流电导率以解释介电特性，这提供了对渗透复合材料中高介电常数和负介电常数行为的普遍原理的重要洞察。同时，当导电填料含量超过渗透阈值时，在现有的渗流理论理论框架的基础上，提出了介电常数的导出公式。APu/Al 渗透复合材料丰富的介电特性将使它们成为电容器和超材料的潜在替代品。