Preparation of low dielectric polyimide/POSS composite foam by carbon dioxide foaming
In order to meet the demand for low dielectric materials in the rapidly developing communication in-dustry,porous materials have received widespread attention due to their low dielectric properties.Carbon dioxide foamed material is an important porous material,and its preparation process is economical and environmentally friendly using physical blowing agents.In order to prepare low dielectric polyimide(PI)materials,we used the CO2 foaming method to prepare PI foams,and investigated the effect of the addition of inorganic particle polyhedral oligosilsesquioxane(POSS)on the pore structure of the composite foams.We systematically investigated the change rule of foam morphology under different saturation and foaming conditions,and prepared composite foams with an average pore size of 0.46 μm and a maximum porosity of 45%.The introduction of POSS and the presence of internal air reduces the dielectric constant of the PI/POSS composite foam,which is 2.35 at a porosity of 45%.The dielectric constant of the PI/POSS composite foam remains stable in the frequency range of 1～106 Hz,while maintaining 30%of the pre-foam tensile strength.
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