Study On Microwave Absorption Properties Of Graphene Supported Rare Earth Oxide And Its Rubber Composites

Graphene has always been used to fabricated microwave absorbing materials due to its high conductivity?large surface area and excellent mechanical properties.Combing graphene with metal oxides or polymer materials is an effective way to prepare microwave absorbing materials.Microwave absorbing materials consists of microwave absorbing agent and matrix which are generally polymer composites.Natural rubber and styrene-butadiene rubber are often used to preparation of functional polymer materials owing to their excellent mechanical properties.Therefore,the two rubbers are selected as substrates in this paper to prepare microwave absorbing materials.Five kinds of microwave absorbing materials,such as cerium oxide immobilized reduced graphene oxide?CeO₂-rGO?,dysprosium oxide immobilized reduced graphene oxide?Dy₂O₃-rGO?,gadolinium oxide immobilized reduced graphene oxide?Gd₂O₃-rGO?,thulium oxide immobilized reduced graphene oxide?Tm₂O₃-rGO?and erbium oxide immobilized reduced graphene oxide?Er₂O₃-rGO?were fabricated by hydrothermal synthesis method.The mass ratio of rare earth oxide to graphene oxide is 10:1.The microwave absorption properties of these composites were investigated via a vector network analyzer,and the results show that CeO₂-rGO has the best microwave absorbing performance.In order to investigate the effect of the ratio of graphene oxide to cerium oxide on the microwave absorption properties,two kinds of CeO₂-rGO-5:1 and CeO₂-rGO-10:1composites with the mass ratio of graphene oxide to cerium oxide 5:1 and 10:1 were prepared.The effects of different mixing modes of cerium oxide and reduced graphene oxide on the microwave absorbing properties were also studied.The minimum reflection loss of CeO₂nanoparticles was-0.63 dB when the thickness was 3 mm.The minimum reflection loss of the pure rGO was-7.47 dB when the thickness was 1 mm.The minimum reflection loss of CeO₂-rGO-5:1 and CeO₂-rGO-10:1 composites were-28.19 dB and-45.94 dB when the thickness were 2.5 mm and 2 mm,and the microwave absorption bandwidth less than-10 dB were 3.60 GHz and 4.48 GHz,respectively.The minimum reflection loss of the CeO₂-rGO-5:1?mixture?and CeO₂-rGO-10:1?mixture?which prepared by mechanical mixing method were-8.92 dB and-2.16 dB when the thickness are 5.5mm and 2.5 mm.It demonstrated that the electromagnetic properties of the composites can be adjusted by changing the ratio of rGO to CeO₂.At the same time,the microwave absorbing properties of the samples prepared by hydrothermal method were better than mechanical grinding method.In order to further explain that the composite of CeO₂ and carbon materials can produce excellent microwave absorbing materials,the multiwalled carbon nanotubes supported cerium oxide composites are also prepared.The mass ratio of cerium oxide to carbon nanotubes are5:1 and 10:1.The results show that when cerium oxide is loaded on carbon nanotubes,the microwave absorption properties of the composites are obviously higher than that of the single component.When the thickness is 2.5 mm,the minimum reflection of CeO₂-MWCNTs-5:1 is-40.95 dB and the microwave absorption bandwidth less than-10 dB is 0.47 GHz.CeO₂-MWCNTs-10:1 with the thickness of 2 mm.The minimum reflectance loss is-17.09 dB and the absorption bandwidth less than-10 dB is 1.6 GHz.Because the microwave absorbing performance of CeO₂-rGO is better than CeO₂-MWCNTs,CeO₂-rGO was selected as the absorber to fill the natural rubber and styrene-butadiene rubber to prepare the rubber microwave absorbing materiasl.The cerium oxide immolized reduced graphene oxide was filled into natural rubber latex and styrene butadiene rubber latex by electrostatic self-assembly method.CeO₂-rGO filled natural rubber?CeO₂-rGO/NR?,CeO₂-rGO filled styrene-butadiene rubber?CeO₂-rGO/SBR?,CeO₂-rGO filled NR then combined with SBR?CeO₂-rGO-NR/SBR?,CeO₂-rGO filled SBR then combined with NR?CeO₂-rGO-SBR/NR?,CeO₂-rGO filled the mixture of NR and SBR?CeO₂-rGO-SBR-NR?were fabricated.The effects of different bonding methods on the absorbing properties were studied.The minimum reflection loss of CeO₂-rGO/NR is-27.26dB when its thickness is 5.5mm,and the absorption bandwidth less than-10 dB is 1.76GHz.Ce O₂-rGO/SBR with a thickness of 5.5 mm and its minimum reflection loss is-19.28 dB,and the absorption bandwidth less than-10 dB is 1.6 GHz.For CeO₂-rGO-NR/SBR when the thickness is 5.5 mm.The minimum reflection loss is-13.88 dB,and the absorption bandwidth less than-10 dB is 0.8 GHz.The minimum reflection loss of CeO₂-rGO-SBR/NR is-8.83 dB when the thickness is 2.5 mm.The minimum reflection loss of CeO₂-rGO/SBR-NR is-12.64dB at the thickness of 5.5 mm,and the absorption bandwidth less than-10 dB is 0.4 GHz.