Microwave Absorbing Materials Based On Natural Rubber Composites With MWCNTs/MoS₂ Hybrids

With the widespread use of electronic devices,electromagnetic radiation as a new type of pollution has captured the attention of human.As a kind of functional material that is capable of absorbing incident electromagnetic wave and attenuating it in the form of heat,microwave absorbing?MA?material has been considered as a potential solution to address the problem of electromagnetic radiation.Recently,construction of multiple electromagnetic loss in matrix via organically capping inorganic nanoblocks is one of effective approaches to fabricate MA materials with features of ultra-light,broad effective absorption bandwidth and high absorption capacity,etc.Here,natural rubber?NR?based composites with multiple electromagnetic loss network has been fabricated via introducing other components,i.e.multi-walled carbon nanotubes?MWCNTs?,molybdenum disulfide?Mo S₂?and styrene butadiene rubber?SBR?.Composites with enhanced electromagnetic properties has been obtained by using dual-fillers with different dimensional structure and thermodynamics favored preferential location of nanoparticles in binary rubber blend.Molybdenum disulfide anchored multi-walled carbon nanotube?Mo S₂-MWCNTs?hybrids were synthesized via hydrothermal synthesis and post-heat treatment,and the influences of annealing temperature on the property have been investigated.Compared with the pure Mo S₂and MWCNT,their combination endows the hybrid enhanced microwave absorption capacity.With the increase of annealing temperature,the absorption capacity of Mo S₂-MWCNTs reaches its peak when the annealing temperature is 300 ^oC.The optimized hybrid exhibits a minimum reflection loss of-30.13 d B and a effective absorption bandwidth of 3.44 GHz.Microwave attenuation mechanism analysis indicates that heat-treatment plays an important role in tuning the electromagnetic characteristics of resulted hybrids.The imperfect of Mo S₂crystal at low temperature should induce impedance mismatching,while loss of MWCNTs at high temperature should lead to poor dielectric loss.To introduce a synergetic effect derived from different dimensional nanoblocks,NR composites with MWCNTs and Mo S₂hybrids were fabricated by conventional mechanical mixing.The morphological results demonstrate that the combination of MWCNTs and Mo S₂synergistically boosts their dispersion in matrix,thus forming more intact electromagnetic loss network.As a result,the microwave absorbing capacity of NR/MWCNTs/Mo S₂composites are more than 12 times higher than that of NR composites with sole MWCNTs or Mo S₂.When 5 vol.%MWCNTs and 5 vol.%Mo S₂were incorporated in NR matrix,the minimum reflection loss and effective absorption bandwidth of resulted composite is-31.08 d B and 3.44 GHz,respectively.Analysis into the mechanism of microwave attenuation indicates that such enhancement in microwave absorbing performance is attributed to the MWCNTs/Mo S₂hybrid induced balance between impedance and attenuation.Based on different interfacial energy-induced preferential distribution of filler in rubber matrix,composites with multiple electromagnetic loss network were designed by using NR/SBR binary blend and MWCNTs/Mo S₂dual-fillers.The results demonstrate that such engineered nanostructure with controlled nanoparticle location is a robust strategy for optimizing microstructure and electromagnetic property of resulted composite.Interestingly,by adopting the compartmentalized approach wherein MWCNTs were in the NR phase and the Mo S₂were in the SBR phase,outstanding reflection loss of-35.73 d B were noted for the obtained composites.Thus,the approach demonstrates that nanoscopic structuring in the rubber blends can be achieved under macroscopic processing conditions and this strategy can further be explored to design microwave absorbers.