The Preparation And Thermal Insulation Property Study Of A Lightweight High-strength Composite

With the development of aerospace industry,the requirements for lightweight thermal insulation materials are getting higher and higher,and the structural strength of traditional foam thermal insulation materials is insufficient.Therefore,it is necessary to develop a high-strength thermal insulation composite material filled with light materials.However,the filling process of lightweight fillers requires a resin matrix with a low viscosity,and therefore a low viscosity modification of the resin is required.By incorporating a large amount of closed-cell lightweight filler in the material,lightweight,high-strength,thermal-insulation integrated materials are prepared to meet the aerospace industry’s demand.In this paper,three kinds of reactive diluents were used to modify the epoxy resin with low viscosity.Two kinds of curing agents were used to form a compound curing system.The influence of reactive diluents on the viscosity of the low viscosity resin system and the compression performance of resin castings were studied in order to optimize a optimal low viscosity resin system.Based on the optimal system,lightweight hollow beads were added to reduce the density and thermal conductivity of the composites.The effects of hollow microbeads on the density,mechanical properties and thermal insulation properties of the composites were investigated and compared with the theoretical calculated thermal conductivity of the material.On this basis,the preliminary study of the insulation mechanism of the light insulation composite thermal was done.The research shows that the effective dosages of the three reactive diluents to reduce the viscosity of the epoxy resin are within 15%.The optimal low-viscosity resin system obtained in this paper is a low-viscosity resin system containing 10% benzyl glycidyl ether diluent.The viscosity of the system is 4150 mPa·s at room temperature,which is a ideal result on reducing the viscosity.The compressive strength of the resin-cast body is 113.6 MPa and the compressive modulus is 2.081 GPa.For the lightweight thermal insulation composites,hollow beads as lightweight lillers,when the volume fraction of the hollow microbeads is less than 30%,the compression fracture mode of the material is the 45° fracture,and the main bearing structure of the material is the low-viscosity resin matrix;when it is above 30%,the fracture is in the form of layer failure,and the main bearing structure is hollow microbeads.When the volume fraction of hollow microbeads is 30%,the best performance is obtained.The material density is 0.91g/cm3,the compressive strength is 83.8MPa,the compressive modulus is 2.29 Gpa and the thermal conductivity is 0.1676W/m·K.The deviation of the material’s thermal conductivity calculated with the parallel model and Maxwell-Eucken model from the experimental value is within 5%.The thermal conduction mechanism of the lightweight thermal insulation composite materials studied in this paper is mainly based on the thermal conduction of the solid and the gas in the hollow microbeads.The gas convection in the hollow microbeads and the thermal radiation of the material have a negligible contribution to the thermal conductivity of the thermal insulating material.