Volume exclusion effect and ambient temperature induced ultrahigh electromagnetic wave absorption properties of polylactic acid (PLA)/graphene nano‐platelets (GNPs) composites

Abstract Conductive polymer composites (CPCs) have an excellent performance in dealing with electromagnetic (EM) radiation. The distribution of conductive fillers in CPCs plays a vital role in the electrical conductivity and EM wave‐absorbing properties. Moreover, the distribution evolution of GNPs in the PLA matrix caused by the enhanced volume exclusion effect via annealing was investigated. Polylactic acid with 8 wt.% graphene nano‐platelets (PG8) achieved best performance among the composites. After 5‐min heat treatment, the electrical conductivity and EM wave absorption properties of PLA/GNPs composites are significantly improved. With a simple treatment, the composite can reach an ultrahigh reflection loss (RL) value of −28.5 dB with a thickness of only 2.5 mm. By controlling the thickness in the range of 1–4 mm, the effective absorption bandwidth can be adjusted within 5.1–8.0 GHz. These methods provided in this work can effectively improve the EM wave absorption performance of CPCs and are worthy of being promoted.