Microwave Properties of Composite Films Based on Polyvinyl Chloride and Oxidized Activated Carbon

Activated Carbon (AC) prepared by the carbonization of pit stones was used as is and was subjected to surface oxidation with nitric acid (HNO3) to be used as carbon filler for polyvinyl chloride (PVC) in order to prepare PVC-based composite films. Thermal analysis of AC and AC-HNO3 revealed the presence of carboxyl, lactone, anhydride, and phenolic groups on the surface of the oxidized AC. The morphological changes for oxidized ACs were imaged by scanning electron microscopy. Microanalysis data showed that treatment with HNO3 increased the oxygen content by up to 15 wt%. In the study, we used X-band microwave frequency analysis to investigate the effect of AC-HNO3 in PVC composite films on the electromagnetic properties. The reflection loss S11 of electromagnetic waves increases with the AC-HNO3 content in PVC-based composites according to a linear law. High concentrations of the AC filler weaken the radio-masking properties of the investigated PVC/AC-HNO3composites while improving the EM wave absorption capability.