Preparation And Propreties Of High Tear Resistance Silicone Elastomer

Silicone rubber elastomer is a semi-inorganic polymers, whose backbone is made of silicon-oxygen bond(Si-O), and its side chain is consisted of silicon atom and other organic groups. Silicone rubber elastomer has a very excellent weather resistance, high temperature resistance sexual, physical inertia, etc. It has a wide range of application in terms of national defense, aerospace, electronics, health care, etc. But low tear strength of silicone rubber has hampered further development and application.Firstly, in the case of a fixed formula, exploring different curing pressure, curing temperature, the rate of pressure release and dwell time have affect on the surface roughness, cell uniformity and mechanical properties and the like of the prepared silicone rubber foam. Single factor variable method drawn: in curing pressure 10 MPa, first period curing temperature 130℃, Second period curing temperature 150℃, the slow rate of release pressure 1MPa/s, 10 s dwell time, good foamed silicone rubber was obtained. It is neat surface, uniformity of cell optimum, and the tear strength reaches a maximum 2.52KN/m, the tensile strength is 0.63 MPa, elongation at break is 360.14%, and the heat resistance at this time is better.Then fumed silica was modified by KH560, calcium sulfate whisker was modified KH560 and stearic acid. According to the infrared spectra analysis and microscopy analysis and activity index analysis, and respectively, to explore the effects of different amount of modified silica, KH560 modified and stearic acid modified whisker on the properties of hypostatic silicone rubber, successful modified fumed silica and calcium sulfate whisker were seen. According to the activity index analysis, KH560 modified fumed silica activity index from 82.3% increased to 93.1%, KH560 modified whiskers activity index from 48.8% increased to 51.8%, stearic acid modified whiskers activity index increased to 84.9%, they also showed the modified better. The results show, when modified silica in the amount of 30%, KH560 modified whiskers in the amount of 40% the properties of hypostatic silicone rubber was excellent, tear strength was 14.23KN/m, tensile strength was 2.94 MPa, elongation at break of 330.21%, density and hardness was greater, was 1.298g/cm~3 and 53.98 HA. Infrared analysis and thermal analyzed the mechanism of performance change of silicone rubber in terms of microstructure and thermal stability at this time. On the basis of exploring the amount of KH560 modified silica and modified whisker to the physical performance of silicone rubber, combined with preparation technology of the foamed silicone rubber and the dosage of the reinforcing fillers,foamed silicone rubber was excellent in terms of smooth, uniform cell, mechanical properties, when modified silica was in the amount of 30%, modified whiskers was 20%. At this time, the tear strength was from 2.57 KN/m to 4.37KN/m, the tensile strength was from 0.52 MPa to 0.91 MPa, elongation at break was from 276% to 304.53%, but it had a certain increase in terms of hardness and density.