Study On The Preparation And Compressive Properties Of Silicone Rubber Foam With Highly Ordered Pore Structure

Silicone rubber foam(abbreviated as "silicone foam")material is a kind of porous polymer elastomer prepared by foaming silicone rubber.It combines the characteristics of the rubber and the foam,such as excellent resistance to high and low temperature performance,excellent weather fastness,low relative density,high specific surface area,large compressible deformation and excellent damping performance.It is usually used as damping and cushioning materials,and has a wide range of applications in extreme conditions of aerospace.The traditional methods of physical foaming and chemical foaming for preparing silicon foam have difficulties in accurately controlling the pore structure,resulting in the problem that the mechanical properties of the prepared foam material are not controllable.In order to overcome the above problems,the T-ZnOw reinforced silicone rubber ink was prepared in this paper.Using the unique patterning capability of 3D printing technology,the silicone rubber ink is printed into the ordered,open-celled silicon foam material,achieving the separation of the foaming process and the curing process,obtaining uniform cell structure and controllable compressive mechanical properties.The experiment of this paper is divided into three parts.The first part is the study of ink materials.The results showed that the modification of T-ZnOw by silane coupling agent had been successful,and the dispersibility of the filler in the matrix had been improved.The ink material had printability and self-supporting properties and met the basic requirements for 3D printing.At the same time,the curing conditions of the ink were also determined in the experiment,ie,curing at 150? for 1h.The second part is the use of direct writing 3D printing technology to print the ink material into the silicon foam with an open-cell structure and study its properties.It was found that the modified zinc oxide whiskers had better dispersion in the matrix,but the particles appeared agglomeration when the content was higher than 4 wt%.The interaction between the mT-ZnOw and the silicone rubber molecular segments limits the movement of the segments,resulting in an increase in Tg and an increase in crosslink density.Next,this paper discussed the effect of modified T-ZnOw content and the printing structure on the mechanical properties of silicone foams.It was found that the mechanical properties of silicon foam were best when the content of modified T-ZnOw was lwt%under the same printing structure and line width(about 270?m).The width of the plateau area was more than 15%,and the buckling stress could reach 0.35MPa.When the filler content and the layer remained the same,the smaller the print line spacing,the greater the mechanical strength of the silicon foam.However,taking into account the shock absorption requirements,the mechanical curve is more ideal when the line spacing is 0.8mm.When the filler content and the line spacing remained constant,the greater the layer,the larger the elastic modulus of the silicone foam,the more pronounced the buckling effect.The width of the platform increased to 30%.When the printing layer number is greater than 14 layers,the size effect no longer has an effect on the mechanical properties.In the third part,the post-treatment of the cured silicon foam material was performed to further improve the mechanical strength.The specific method was to use a UV light with a wavelength of 254 nm to irradiate the silicon foam,and to explore the best condition by changing the irradiated time.Since the energy of the short-wave UV light was greater than the chemical bond energy in the silicon foam molecule,the chemical bonds on the surface were cut or weakened after irradiation,and the mechanical strength increased.The SEM test,FTIR test,hydrophobic angle test,and cross-link density test of the material verified the above statements.Since the UV light can only act on the surface of the sample,although the elastic modulus of the material increased by up to 57%;the buckling stress didn't increase much.By observing the compressive stress-strain curves of the silicon foam at different irradiation time,it can be determined that 2 minutes was the best.The above experimental results show that the direct-writing 3D printing technology is not only simple and environmentally friendly,but also can produce silicon foams with excellent mechanical properties.With the diversification of the application scenarios of silicon foams,the market for preparing silicon foams using 3D printing technology will be broader.