N-doped carbon derived from thermoplastic and thermosetting polyimides toward electromagnetic waves absorption

Abstract

Due to stronger tunability, higher stability, and low production costs, polymeric material-based carbon materials are considered to have the potential to become high-performance electromagnetic wave absorbing (EWA) materials. In this work, polymer-derived carbon is made by pyrolyzing thermoplastic polyimide (TPPI) and thermosetting polyimide (TSPI) at different temperatures. Using Raman and XPS analysis, the graphitization degree and defect content of carbonized TPPI and TSPI are obtained. The reflection loss is calculated by through their electromagnetic parameters. The prepared carbonaceous materials exhibit excellent EWA performance. Specifically, the maximum effective absorption band (EABmax) of carbonized TSPI at 1500 C can reach 4.1 GHz with thickness of 1.8 mm, and that of carbonized TPPI at 900 C can reach 4 GHz at lower thickness of 1.6 mm. The different structures of TPPI and TSPI result in different degrees of graphitization and defect content at the same temperature, which further leads to differences in their EWA performance. This work provides inspiration for studying the influence of precursor structure on the EWA preformation of carbon materials obtained through pyrolysis.