Nanocomposites and nanomaterials

Influence of the structure of polymer nanocomposites on the shielding effectiveness of electromagnetic radiation
Mamunya Ye.P.1, Sushko O.Yu.2, Maruzhenko O.V.1, Paraschenko I.M.1, Misiura A.I.3, Dubrovka F.F.2
1 Institute of Macromolecular Chemistry of the NAS of Ukraine  
E-mail: ymamunya@ukr.net
2 National Technical University of Ukraine "Igor Sikorsky KPI"
3Taras Shevchenko National University of Kyiv

Currently, there is great interest in the development of electromagnetic shielding and microwave absorption of materials, as the effect of electromagnetic radiation (EMR) on biological, electronic, and technical objects is a significant factor affecting their vital functions and operation. Absorbing materials have to interact with both the electrical and magnetic components of the electromagnetic wave for its efficient absorption and should have maximum absorption and minimum reflection of EMR, minimum weight, high mechanical strength, corrosion resistance, etc. The most promising materials that meet these requirements are polymer composites that contain electrically conductive fillers.
Microwave absorption depends on three factors: dielectric and magnetic losses and electrical conductivity (EC). The shielding effectiveness SE (dB) is defined as SE = SEA + SER, i.e. equal to the sum of the absorption SEA and reflection SER effectiveness. The SEA and SER increase with increasing EC, but it is important to achieve the highest SEA/SER ratio, i.e. the maximal value of SEA.
In this work, we investigated polymer nanocomposites based on polyethylene (PE) and organo-inorganic polymer (OIP), which contained nanofillers carbon black (CB), carbon nanotubes (CNT), and iron oxide (Fe2O3). Magnetic Fe2O3 provides absorption of the magnetic component of EMR, while CB and CNT provide electrical conductivity, and OIP has a high dielectric constant (DC) to interact with the electrical component of EMR. Also, an ordered segregated filler structure is formed in the PE matrix. Measurement of the shielding parameters was performed at a frequency of 10 GHz. It was found that the SEA of composites is proportional to EC0.5, but the composites based on OIP reach the same value of SEA as PE composites at EC value, which is two orders of magnitude lower due to the presence of high DC, additionally having minimal SER value. The highest value of SEA shows PE nanocomposite with a combined filler CB/CNT due to the hybridization of these carbon fillers and the presence of a segregated structure.