Highly thermally conductive and superior electromagnetic interference shielding composites via in situ microwave-assisted reduction/exfoliation of expandable graphite

A facile route based on the solid-state shearing milling and microwave-assisted sintering was developed to convert the aluminum-plastic packaging waste (APPW) into the multifunctional material. The expandable graphite flakes acted as the "welding joints" in the interfacial regions to sinter the APPW powders into a composite part with continuous networks. Interestingly, the APPW/expanded graphite composites prepared by microwave-assisted sintering showed a superior electrical conductivity and a better thermal conductivity than the samples fabricated by the hot molding method due to the in-situ reduction and exfoliation of expandable graphite. In this case, the sintered APPW/expanded graphite composites showed a high EMI SE of 60 dB and an excellent thermal conductivity as high as 5.22 W/(m.K) with 17.5 vol% expandable graphite loading. This study provides a facile and clean method to manufacture value-added products from plastic wastes, which will not only alleviate environmental pollution but also reduce energy consumption.