Natural rubber (NR) based nanocomposites containing a constant amount (50 phr) of standard furnace carbon black and graphene nanoplatelets (GNP) in concentrations from 1 to 5 phr have been prepared. Their dielectric (d ielectric permittiv ity, dielectric loss) and microwave propert ies (coefficients of absorption and reflect ion of the electro magnetic waves and electromagnetic interference shielding effectiveness) have been investigated in the 1-12 GHz frequency range. The results achieved allow us to reco mmend GNP as second filler for natural rubber based composites to afford specific absorbing properties.
A novel nitrile butadiene rubber (NBR)/ magnetite (Fe 3 O 4 ) nanocomposite for electromagnetic interference (EMI) shielding at microwave frequency was successfully fabricated. The structural features of assynthesized magnetite and NBR/Fe 3 O 4 were examined by X-ray diffraction, field emission scanning electron microscopy, transmission electron microscopy, and energydispersive X-ray spectroscopy. The number of elastically effective chains, volume fraction of rubber, interparticle distance among conductive sites, polymer-filler interaction, and porosity of the nanocomposites were evaluated. The mechanical properties, including the tensile strength, elongation at break, and hardness, of the composites were measured. The static electrical properties, such as the elec-trical conductivity, carrier mobility, and number of charge carriers, as a function of magnetite content were evaluated. The interrelation between the electrical conductivity, shielding effectiveness (SE), dielectric constant, and skin depth of the composites are discussed. Finally, the EMI SE versus frequency was tested. The results reveal that an SE of 28-91 dB against EMI in the 1-12 GHz range depended on the loading of the conducting magnetite within the NBR matrix. Accordingly, these nanocomposites may used in the field of microwave absorption devices.
Polyvinyl chloride-(PVC)-based nanocomposites, containing graphite nanosheets (G), which may be used as electromagnetic wave absorbers was developed and investigated. The microstructure of polyvinyl chloride/ graphite nanocomposites (PVC/G) were examined by means of X -ray diffraction, scanning electron microscopy (SEM), and thermal gravimetric analyses (TGA). SEM image reveals that the graphite nanosheets were well dispersed in the PVC matrix without agglomeration. Thermal stability of the PVC/G nanocomposites is improved as a result of inclusion of graphite nanosheets. The PVC/G nanocomposites were characterized to investigate the effect of dispersion of graphite nanosheets in PVC matrix. The dielectric spectroscopy of PVC/G nanocomposites in frequency range from 1 to 12 GHz has been performed. The results show that PVC/ G nanocomposites exhibit high dielectric constant at the measured frequencies. Coefficient of attenuation and coefficient of reflection of PVC/G composites have been also examined in a frequency range from 1 to 12 GHz. The electromagnetic interference shielding effectiveness (EMI) depends on graphite volume fraction in the composite. The results show that the PVC/G represents a new class of conducting lightweight nanomaterial that can absorb electromagnetic waves at microwave frequency and may be promising for future commercial use.
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