When mixing silicone rubber with different vinyl content, the overall performance of vinyl molar fraction in the range of 0.10% to 0.25% is excellent, and key properties such as tear strength can be significantly improved through reasonable proportions.The specific analysis is as follows：


Performance optimization mechanism
Centralized crosslinking structure: When silicone rubber with high vinyl content (such as 0.15%) is mixed with silicone rubber with low vinyl content (such as 0.06%), a “centralized crosslinking” structure will be formed during the vulcanization process.The vinyl enrichment area becomes the crosslinking center, and the stress is evenly dispersed to the surrounding molecular chain through these centers under the action of external forces, avoiding the problem of one-by-one fracture of the crosslinking bonds in a single dispersed crosslinking structure, thereby significantly improving the tear strength.
Experimental verification of the ratio: When silicone rubber with a vinyl molar fraction of 0.15% and silicone rubber with a vinyl molar fraction of 0.06% are mixed in a 50/50 ratio, the tear strength can reach 45.8kN/m, which is more than 100% higher than a single component; when silicone rubber with a vinyl molar fraction of 0.30% and 0.06% are mixed in a 4/96 ratio, the tear strength still reaches 42.9kN/M.
Effect of vinyl content on performance
Mechanical properties: When the vinyl content is too low (≤0.10%), the hardness and tensile strength of silicone rubber are low, and the elongation and permanent deformation are large; as the vinyl content increases, the hardness increases, the elongation and permanent deformation decrease, and the tensile strength and tear strength peak.When the molar fraction of vinyl is in the range of 0.10% to 0.25%, the overall performance of silicone rubber is better.
Vulcanization characteristics: When the molar fraction of vinyl is in the range of 0.05%~0.40%, the vulcanization rate of silicone rubber rubber is close; however, after exceeding 0.40%, the vulcanization rate decreases significantly.
Thermal stability and aging resistance: High vinyl content (>0.40%) will reduce thermal stability, but it has little effect on aging resistance.Silicone rubber with a vinyl mass fraction of 0.22% has good heat resistance stability.
Thermal conductivity: Silicone rubber with low vinyl content has better thermal conductivity than silicone rubber with high vinyl content.Silicone rubber with a vinyl mass fraction of 0.04% has the best thermal conductivity and thermal diffusivity.
Ratio recommendations in practical applications
High tear strength requirements: It is recommended to mix components with large differences in vinyl molar fraction, such as 0.15% and 0.06% silicone rubber mixed in a 50/50 ratio.
Balance the vulcanization rate and thermal stability: select the components with a vinyl content in the range of 0.10% to 0.25% for mixing.
Special performance requirements: If you need to prepare low-hardness, high-elasticity thermally conductive silicone rubber, you can choose silicone rubber with low vinyl content (such as 0.04%); if you need high-hardness, high-tear-strength materials, you can appropriately increase the proportion of components with high vinyl content.