Preparation And Mechanical Properties Of Silicone Rubber Materials With Foam/Solid Alternating Multilayered Structure

Silicone rubber foam material is a kind of porous polymer elastic material,which not only has the advantages of high and low temperature resistance,aging resistance,radiation resistance,water resistance and biological compatibility of silicone rubber,but also has the physical characteristics of foam materials such as low density,high elasticity and good absorption of mechanical vibration or impact.Therefore,silicone rubber foam materials are widely used in packaging,transportation,electronic industry and aerospace and other fields.However,the silicone rubber foam prepared by the traditional foaming process has such problems as large cell size,low cell density and uneven cell size distribution,leading to the common silicone rubber foam has lower tensile strength than the solid silicone rubber material,poor compression resistance.To solve these problems,make more widely the application scope of silicone rubber material,based on the cell size,dimension control and more green environmental protection of the supercritical fluid foaming method,combined with laminated hot pressing technology and fabrication of a series of alternating multilayered co-extrusion foam/soild alternating layers of silicone rubber foam materials and the microstructure and mechanical properties are studied.Firstly,a series of mixed adhesives with different rheological properties have been prepared by taking methyl vinyl silicone rubber as matrix and Si O₂ as inorganic filler by gas phase method.Then a series of silicone rubber foams with different cell structures are prepared by supercritical CO₂ foaming technology.The results show that the structure of silicone rubber foam can be controlled by controlling the viscoelasticity of silicone rubber matrix.Under the same foaming process,the soild silicone rubber and silicone rubber foam with the size of 18.21?m and the cell density of 1.75×10⁸ cells/cm³ can be prepared.Secondly,a series of multilayered solid silicone rubber materials are prepared by means of alternating multilayer co-extrusion technology and laminated thermal pressing technology.The results show that,compared with single-layer silicone rubber,multilayered solid silicone rubber has two-dimensional continuous layered structure,and the mechanical properties can be improved by building silicone rubber into multilayered structure.Finally,the silicone rubber foam material with alternating multilayered structure of foam/solid was successfully constructed by using laminated thermal pressing technology and supercritical CO₂ foaming technology,and its cell characteristics and mechanical properties are systematically studied.The results show that by introducing solid silicone rubber material alternately and directionally into the silicone rubber foam material,the cell growth in supercritical foam can be restricted,and the cell size of the foam layer can be smaller and denser.Under the same preparation process,the foam/solid alternately layered silicone rubber material has lower cell size and larger cell density compared with pure silicone rubber foam.The tensile strength of the foam/solid alternating layered silicone rubber material can reach 5.39 MPa,which is46%higher than that of the pure silicone rubber foam.Moreover,when the compression deformation reaches 40%,the stress of alternating layered silicone rubber material can reach 0.89 MPa,which is 175%higher than that of pure silicone rubber foam material.