Study On RAM-MCPCM Composites With Infrared And Microwave Compatible Stealth Function

In this paper,two different types of microencapsulated phase change material(MCPCM),LMPCM and BMPCM,were prepared with the method of the seeded micro-suspension polymerization,which use poly(styrene-divinylbenzene)as wall material and lauric acid and n-Butyl stearate as phase change core material in the medium temperature zone and in the low temperature zone respectively.Four types of radarabsorbing-MCPCM(RAM-MCPCM),Fe3O4-LMPCM,RGO-LMPCM,Fe3O4-BMPCM and RGO-BMPCM,were prepared by assembling nano Fe3O4 particles,RGO radar absorbing materials(RAM)on the surface of MCPCM through the in-situ method.The infrared microwave stealth coatings and RAM-LMPCM/PS infrared microwave stealth composites were prepared by using RAM-MCPCM as functional filler.The chemical composition,microstructure,thermal properties and magnetic properties of RAM-MCPCM were characterized and measured through FT-IR,SEM,particle size analyzer,DSC,TG and vibrating sample magnetometer(VSM),etc.Applying the vector network analyzer,the electromagnetic wave absorbing properties of the coatings were tested through arch test method.The infrared stealth properties of the coatings were tested through using homemade one-dimension plate heat transfer model.In accordance with the national standards,the mechanical properties of the coatings were tested.The thermal properties and microstructure of RAM-LMPCM/PS composites were characterized.The infrared stealth properties,fracture behavior and tribological properties of composites were determined.The results indicate that LMPCM and BMPCM have regular spherical morphology with smooth surfaces,RAM-LMPCM and RAM-BMPCM are have regular spherical morphology with slightly convex surfaces.With the optimized core wall mass ratio of 1.5:1,the latent heat of phase change and encapsulation ratio of the LMPCM are 99.2 J/g and 57.4% respectively;with the condition of w(Fe3O4)=8.0%,the latent heat of phase change of the Fe3O4-LMPCM is 85 J/g;with the condition of w(RGO)=2.0%,the latent heat of phase change of the RGO-LMPCM is 90 J/g.With the optimized core wall mass ratio of 1.4:1,the latent heat of phase change and encapsulation ratio of the BMPCM are 66.5 J/g and 55.4% respectively;with the condition of w(Fe3O4)=8.0%,the latent heat of phase change of the Fe3O4-BMPCM is 63 J/g;with the condition of w(RGO)=2.0%,the latent heat of phase change of the RGO-BMPCM is 65 J/g.With the coating thickness of 0.5mm,the Fe3O4-LMPCM/epoxy coating at 5.25 GHz reaches the maximum absorption peak of-0.54 d B,the RGO-LMPCM/epoxy coating at 8.8GHz reaches maximum reflectivity of-1.21 d B,the Fe3O4-BMPCM/epoxy coating at 5.3GHz reaches the maximum absorption peak of-0.50 d B and the RGO-BMPCM/epoxy coating at 8.8GHz reaches maximum reflectivity of-1.13 d B.Epoxy coating and PS doped RAM-MCPCM in the phase change temperature range can effectively shield the target infrared radiation and achieve the goal of infrared stealth.In the process of friction,RGO-LMPCM make polystyrene substrate material have certain lubrication and anti-friction effect.With the condition of w(RGO-LMPCM)=20%,RGO-LMPCM/PS composite has average friction coefficient of 0.51.The comprehensive analysis shows that: RAM-MCPCM which adopt the method of the seeded micro-suspension polymerization have regular spherical morphology.The microcapsules after doping RAM still have higher latent heat of phase change and encapsulation ratio.Composite materials using RAM-MCPCM as Functional filler have infrared microwave compatible stealth function.The right amount of RAMMCPCM has certain effect of enhancing and toughening the coating.