Preparation And Electromagnetic Shielding Properties Research Of Open Cell Polysiloxane Foams

Polysiloxane foam is a kind of functional polymer materials.Because of its good performances of high and low temperature resistance,chemical stability,electrical insulation and biocompatibility,it is widely used in many domains,such as aerospace,military,biomedical and electronic devices.The open-cell foam is prepared by the dissolution method,which is simple,green and pollution-free.Compared with closed-cell foam,polysiloxane open-cell foam has a higher specific surface area,better mechanical properties,and a simpler preparation process.In this paper,graphene oxide and MXene nanomaterials are applied to the preparation of polysiloxane open-cell foam.The thermal stability and electromagnetic shielding performance of polysiloxane composite foam are studied.The main contents of this paper are as follows:1.Polysiloxane open-cell foam was prepared by using elution method where soft white sugar was used to be the pore-forming agent.Graphene oxide,polyacrylic acid and polyethyleneimine are assembled layer by layer,which deposited on the surface of the polysiloxane foam cells to form a graphene oxide layer to prepare a kind of polysiloxane open-cell foam composite materials.The assembly of graphene oxide on the surface of polysiloxane cells reduces the average cell diameter.Graphene oxide can improve the thermal stability and electromagnetic shielding performance of the composite foam.In nitrogen atmosphere,the maximum decomposition rate of composite foam increased from 464.7℃to 581.6℃,and the residual carbon content in air atmosphere of 850℃increased from 63.7℃to 70.1℃.By changing the number of graphene oxide layers,the electromagnetic shielding performance can be controlled.When the number of graphene oxide layers reaches four,the shielding effectiveness SE_Total increases from 0.14 d B to 0.30 d B.2.Ti₃C₂T_x-MXene nanomaterials was prepared by etching-intercalation of Ti₃AlC₂-MAX ceramic phase materials.Fe₃O₄ was compounded on the surface of Ti₃C₂T_x and added to the polysiloxane matrix to prepare polysiloxane open-cell foam.Ti₃C₂T_x@Fe₃O₄ can improve the thermal stability of the composite foam.At 850℃,after adding 0.5wt%Ti₃C₂T_x@Fe₃O₄,the residual carbon content of the composite foam at 850℃increased from 52.23%to 60.42%,and it continued to increase with the increase of the addition.After adding Ti₃C₂T_x@Fe₃O₄ to the matrix,the shielding effectiveness is increased from 11 d B to 13.5 d B.