| In the military field,with the development of radar detection and recognition technology,higher requirements have been put forward for radar stealth technology and absorbing composite materials,making absorbing composite materials a research hotspot.Absorbing composite materials are generally composed of absorbing agents,matrix resins,and mechanical reinforcing materials.The electromagnetic parameters of absorbing composite materials mainly depend on the absorbing agents,while the mechanical properties and corrosion resistance of the materials depend on the matrix resins and reinforcing materials,and are influenced by the interface compatibility between the absorbing agents,reinforcing fillers,and matrix resins.Glass fiber is a common reinforcing material,which has the advantages of corrosion resistance,high strength,and low cost,and can improve the performance of materials.It is one of the most commonly used reinforcing materials in composite materials currently.However,glass fiber is a transmissive material,and its addition can affect the absorbing effect of absorbing composite materials.If the glass fiber itself has absorbing properties through modification,it is expected to solve the above problem.This paper focuses on glass fiber as the research object,introduces a poly-p-phenylene layer with excellent dielectric properties and low density on its surface,prepares a glass fiber@poly-p-phenylene composite absorbing agent,and adds it to an epoxy resin matrix to prepare a new type of absorbing composite material.The mechanical and absorbing properties of the material are characterized.Firstly,in this paper,glass fiber was used as the matrix,and a series of glass fibers with different treatment effects were prepared by pretreating them with sodium hydroxide solution,changing the concentration and treatment time of the sodium hydroxide solution.Poly-p-phenylene was coated on the surface of the glass fibers,and its properties were tested to obtain the best glass fiber treatment conditions and the optimal amount of poly-p-phenylene for coating.The results showed that within the concentration range of 10-40 wt%,the higher the concentration of the sodium hydroxide solution,the more complete the coating effect of poly-p-phenylene.When the concentration of sodium hydroxide was 40 wt% and the glass fiber was treated for 40 min,the glass fiber treated under this condition was most suitable for coating with poly-p-phenylene,and the amount of poly-p-phenylene monomer was 60 wt%.The prepared glass fiber@poly-p-phenylene material had the best absorbing performance.At a wax filling of 20 wt% and thickness of 2mm,it could achieve-22.08 d B at 14.96 GHz,and the effective absorption bandwidth was4.80 GHz(11.92-16.72 GHz).Secondly,after determining the optimal amount of pyrrole monomer,the morphology of the polypyrrole was controlled by introducing the surfactant cetyltrimethylammonium bromide(CTAB)during the polymerization process of pyrrole.By changing the amount of CTAB,the relationship between the morphology and absorption properties of the glass fiber/polypyrrole composite material was investigated.The results showed that the best absorption performance was achieved when the molar ratio of CTAB to pyrrole monomer was0.3.The optimal filling amount of the material in paraffin was 20 wt%,resulting in the best reflection loss of-37.59 d B and an effective absorption bandwidth of 5.92 GHz.Finally,glass fiber,polypyrrole,and the prepared glass fiber/polypyrrole composite absorber were added to epoxy resin E51,and the mechanical and absorption properties of the samples were compared to explore their feasibility in practical applications.The results showed that when the glass fiber/polypyrrole composite absorber E51-4 was added to the epoxy resin at 20 wt%,the mechanical properties were only slightly affected,but the absorption performance was significantly improved.The best reflection loss at 2.5 mm was-15.30 d B,and the effective absorption bandwidth was 1.76 GHz(16.24-18.00 GHz)compared to pure epoxy resin. |
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