Preparation And Performance Study Of Functional Microcellular Silicone Rubber Foams

Microcellular silicone rubber foam is widely used as cushion damping material,insulation and heat insulation materials due to its unique properties of light weight,high elasticity,insulation,stable quality in large temperature range.However,the silicone rubber foam prepared by the batch supercritical CO₂ foaming method generally has the problem of poor apparent quality,which limits the subsequent research and practical application of the material seriously.In this paper,the influence of silicone oil on the elastoplasticity of vulcanized silicone rubber was studied,and the most suitable mixing ratio was found to prepare the apparently smooth and flawless silicone rubber foam by supercritical CO₂ foaming technology.The effects of cell morphology on mechanical performance and thermal conductivity were investigated further.The minimum cell diameter of the silicone rubber foam is 0.92?m,and the corresponding cell density can reach to 3.79×10¹00 cells/cm³.The silicone rubber foam has a maximum tensile strength of 4.77 MPa and the relative break elongation is 1866.29%.In addition,the minimum compression deformation of the silicone rubber foam is only 1.62%,and the minimum thermal conductivity of the silicone rubber foam is 0.14 W/m·k.The conductive silicone rubber foam was prepared by adding nano conductive fillers?carbon black,carbon nanotube?to silicone rubber matrix.The dispersion and rheological behavior of the filler in the silicone rubber matrix were investigated,and the conductive behavior and electromagnetic shielding effectiveness of two carbon-based fillers and their compound system in silicone rubber were studied.The results show that it is easier to form a conductive network in the compound system than single filler composite,and the composite material exhibits higher electrical conductivity and electromagnetic shielding effectiveness.The hydrophobic fumed silica with smaller particle size was selected as the reinforcing filler to increase the surface roughness of the composite.Based on the high apparent quality silicone rubber foam,the foam surface with micro/nano structure was successfully constructed by using micropore,and the effect of cell morphology on the surface wettability of the foams was studied.The results show that the multi-stage roughness of the foam surface is beneficial to improve the hydrophobic properties of the material.Contact angle of the composite increases from 103^o to 138^o,and in a particular situation,the superhydrophobic state can be achieved.In addition,the thermal conductivity of the material can be as low as 0.087 W/m·K after removing the surface.In this paper,several silicone rubber foam with different functions were obtained by supercritical CO₂ foaming method.Efforts have been made to research the special properties of materials and expand its range of applications further.