Preparation And Properties Of Light Weight Polymer Composite Materials With Low Thermal Conductivity

It is very important to study the novel multi-functional composites with low thermal conductivity,high strength and light weight,which possess significance to realize the efficient utilization of resources and energy,energy saving and emission reduction,and the sustainable development of environment and society.In this paper,polymeric composites with light weight and high thermal conductivity were prepared via liquid-phase impregnation,molding process and high-temperature curing process to meet the needs of the emerging technologies,such as aerospace,military,construction and industrial fields.Thise research work contains four parts as follows:?1?Unsaturated polyester resin based composites were prepared from compression molding,which filled with a variety of hollow glass microspheres?HGM?,calcium carbonate,talc,mica powder and continuous glass fiber cloth with the matrix resin.The thermal conductivity of the composites was measured by a steady state method.We studied the influence of the filling amount of HGM on the strength of the composites by a series of static compression and bending experiments,and analyzed the reason of the corresponding influence.As a result,the density and thermal conductivity of the composites decrease with increasing the concentration of HGM.The thermal conductivity of the composites reaches as low as 1.180 W/?m·K?when the HGM is filled by 25%.The bending strength of the composites increases at the initial stage but then decreases with the increase of the filling amount of HGM,while the filling of the inorganic filler reduces the bending strength of the composites,The maximum bending strength is as high as 223.176 MPa when the HGM is filled with a concentration of 10%.The compressive properties of the composites decrease with the increase of the filling amount of HGM,but increase with the further adding inorganic filler.?2?A series of hollow glass microspheres/glass fiber felt/silicone resin composites were prepared by compression molding.The thermal conductivity of the composites was measured by steady state method.We studied the influence of the concentration of HGM on the strength of the composites by a series of stretching,bending and static compression experiments,and systematically analyzed role of fillers on the properties of composites.The results show that the density and thermal conductivity of the composites decrease with the increase of the HGM filling amount,and the thermal conductivity of the composites decreases by 44% when the HGM is filled with 10%.Keeping the volume of the filler consistent,the density and thermal conductivity of composites significantly decrease with adding the calcium carbonate instead of the same amount of HGM.The tensile,compressive and bending properties of the composites decrease with the increase of HGM loading.The tensile,compressive and bending strength of the composites decrease by 33.46%,14.30% and 17.39%,respectively,as the content of HGM was 10%.The mechanical properties of composites also increase with filling calcium carbonate instead of adding the same amout of HGM.?3?A series of hollow glass microspheres/silicone rubber composites were prepared by compression molding.The results indicate that the density,thermal conductivity and thermal decomposition rate of composites filled with HGM-H40,decrease by 26.9%,48.3% and 16.16%,respectively.In addition the density,thermal conductivity and thermal decomposition rate of composites filled with HGM-H60 decrease by 17.2%,45.2% and 11.54%,respectively.It indicated that HGM was an excellent light weight filler with low thermal conductivity.The thermal stability of composites has been improved.The tensile strength,frictional properties and elongation at break of the composites decrease with the increasing of the filling amount of HGM.However,both the elastic modulus and Shore hardness increase withthe further adding HGM.?4?Three kinds of hollow SiO₂ were prepared by a template method with calcination under air,nitrogen and ammonia,respectively.Three hollow SiO₂ structures were characterized via scanning electron microscopy and transmission electron microscopy.A series of hollow silica/silicone rubber composites were prepar-ed from compression molding.The results suggest that three kinds of hollow SiO₂ have been successfully prepared.With the increase of the content of SiO₂,the density of the composites decrease and the mechanical properties decreases at the same time.As the modified air was calcined,the tensile strength of the composites decreases by 41.87%.Besides,the optical properties of the calcined SiO₂ filled composites are much better than nitrogen calcination and ammonia calcination of SiO₂ filled composites.The comparative analysis shows that the mechanical and optica l properties of the composites with the modified SiO₂ are better than those ones containing fillers without chemical modification.