Introduction
Briefly describe the wide application of silicone rubber in industry and daily life.
Point out that fumed silicone rubber and precipitated silicone rubber are important categories of silicone rubber, and lead to a discussion on the performance differences between the two.
Preparation basis of fumed silicone rubber and precipitated silicone rubber
Introduce the preparation method of fumed silicone rubber, emphasizing that it is made into silica by high-temperature hydrolysis of halosilanes in a hydrogen-oxygen flame, and then into silicone rubber.
Describe the preparation process of precipitated silicone rubber, which is generated by the reaction of sodium silicate with sulfuric acid and then used in silicone rubber production.
Differences in physical properties
Appearance and transparency
Analyze the reasons why fumed silicone rubber usually has high transparency, such as small silica particle size and uniform dispersion.
Describe the relatively low transparency of precipitated silicone rubber and related factors.
Hardness and tensile strength
Discuss the performance of fumed silicone rubber with high hardness and tensile strength under the same formula due to the good reinforcement effect of silica.
Compare the general level and influencing factors of hardness and tensile strength of precipitated silicone rubber.
Tear strength
Discuss the characteristics of high tear strength of fumed silicone rubber and its advantages in practical applications.
Analyze the characteristics of tear strength of precipitated silicone rubber and its applicability in different scenarios.
Chemical property differences
Aging resistance
Explain the principle that gas phase silicone rubber has better weather resistance and ozone aging resistance due to its molecular structure and white carbon black characteristics.
Explain the degree of aging resistance of precipitated silicone rubber and possible shortcomings.
Chemical corrosion resistance
Study the tolerance of gas phase silicone rubber to different chemical substances, such as acid, alkali, organic solvents, etc.
Compare the performance of precipitated silicone rubber in chemical corrosion resistance and the reasons for the differences.
Processing performance differences
Mixing process
Describe the equipment requirements and precautions for mixing gas phase silicone rubber, because its white carbon black is highly active.
Explain the relatively easy mixing characteristics of precipitated silicone rubber and related process advantages.
Molding process
Analyze the performance of gas phase silicone rubber in extrusion, molding and other molding processes, such as fluidity, demolding, etc.
Compare the characteristics of precipitated silicone rubber molding and the applicability of the two in different molding processes.
Conclusion
Summarize the main differences between gas phase silicone rubber and precipitated silicone rubber in physical, chemical and processing properties.
The importance of rationally selecting these two silicone rubbers according to different application requirements is emphasized.