Yi-Ran Li,Ying-Ming Li,Bing-Bing Chen,Wen-Juan Hu,De-Yi Wang
Ideal electromagnetic absorbing material should not only be light weight, broadband and high efficient, but also easily prepared and flame-retarding to satisfy the challenges from rapid development of electronic information technology. In present paper, a new type of electromagnetic absorbent (Fe-MOF-rGO) was prepared via a simple one-pot method to grow metal-organic framework (Fe-MOF) on the surface of in-situ reduced graphene oxide (rGO) by solvothermal method. When 25 wt% of Fe-MOF-rGO was incorporated into the paraffin matrix, the minimum reflection loss value (RL) reached to −43.6 dB at the thickness of 2 mm, and the effective absorption bandwidth (EAB) exceeded 5.0 GHz, which satisfied the goals of high efficiency, light weight and broadband. According the medium permittivity loss, magnetization loss and excellent resistance matching results, it was concluded that the conduction loss (excellent conductivity of rGO), magnetic loss (magnetic resonance of Fe nanoparticles) and interface polarization loss (heterostructure of two-dimensional rGO and three-dimensional Fe-MOF) of Fe-MOF-rGO jointly determined the electromagnetic absorbing performance. Moreover, the combustible behavior of Fe-MOF-rGO was also investigated. When 10 wt% of Fe-MOF-rGO was incorporated into the epoxy resin (EP), the heat release capacity (HRC) and peak heat release rate (PHRR) decreased by 42.1% and 42.3% respectively, which showed an excellent flame-retarding property.
With the popularity of wireless communication technology, the problem of electromagnetic radiation and interference is highlighted, and the development of efficient electromagnetic shielding materials has become a research priority. In this study, firstly, polyvinyl alcohol/sodium alginate (PVA/SA) hydrogels were prepared by physical cross-linking method, and further, iron-based metal-organic frameworks (Fe-MOFs) were prepared by solvothermal synthesis method, and with reduced graphene oxide (RGO) as a conductive filler, and γ-aminopropyltriethoxysilane (KH550) as a cross-linking agent, were prepared by chemical cross-linking method. Modified polyvinyl alcohol/sodium alginate/iron based metal organic framework/reduced graphene oxide (PVA/SA/Fe-MOF/RGO-KH550) composite hydrogel. The results show that the composite hydrogel has a compressive stress of 20.13 MPa, a compressive strain of 83.28 %, and an electromagnetic shielding efficiency of 39.98 dB at a thickness of 3 mm, which reaches the mid-range and high-end level, and it can be applied to industrial control, small and medium-sized data centres, automotive electronics, and general medical devices with medium-high requirements. The excellent performance of the hydrogel comes from the conductive properties and interfacial polarisation effect of RGO, the dielectric loss of Fe-MOF, which work in synergy, and KH550 optimises the interfacial bonding between the filler and the substrate to form a denser crosslinked structure, which strengthens the mechanical properties and electromagnetic shielding effect. The hydrogel preparation process is simple and low-cost, which provides a reference for the design of high-performance electromagnetic shieldingmaterials and an effective solution to the problem of electromagnetic interference.
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