Silicone rubber with different vinyl content can be mixed and used, and the overall performance can be significantly improved through a reasonable ratio.As the active crosslinking point in the molecular chain of silicone rubber, vinyl directly affects the crosslinking density and mechanical properties of vulcanized rubber.When silicone rubber with high vinyl content and low vinyl content is mixed, a “concentrated crosslinking" structure will be formed during the vulcanization process-the vinyl enrichment area becomes the crosslinking center, and the stress under the action of external forces is evenly dispersed through these centers to the surrounding molecular chain, thereby avoiding the problem of one-by-one fracture of the crosslinking bonds in a single dispersed crosslinking structure, significantly improving tear strength and tear resistance.


Specifically, silicone rubber with a vinyl molar fraction in the range of 0.10% to 0.25% has better overall performance.For example, when silicone rubber with a vinyl molar fraction of 0.15% is mixed with 0.06% silicone rubber in a 50/50 ratio, the tear strength can reach 45.8kN/m, which is more than 100% higher than a single component; and when silicone rubber with a vinyl molar fraction of 0.30% and 0.06% is mixed in a 4/96 ratio, the tear strength still reaches 42.9kN/M.This performance improvement stems from the optimization of the crosslinking structure: the high-vinyl component provides the crosslinking center, and the low-vinyl component extends the length of the molecular chain. The synergy between the two enables the material to disperse stress by concentrating the crosslinking point when under force, and it can rely on the long molecular chain to absorb energy, thereby enhancing the tear resistance.


In addition, mixed use can also adjust the vulcanization rate and hardness.When the vinyl content is 0.05%~0.40%, the vulcanization rate of silicone rubber is close; however, after exceeding 0.40%, the vulcanization rate decreases significantly.By mixing silicone rubber with different vinyl content, the vulcanization speed and thermal stability can be balanced (too high vinyl content will reduce thermal stability), and the hardness can be adjusted to meet the needs of different application scenarios.For example, when high strength and heat resistance are required, the proportion of high vinyl components can be increased; when flexibility is required, the proportion of low vinyl components can be increased.


In practical applications, the ratio needs to be optimized according to specific performance requirements.For example, when preparing high tear strength silicone rubber, it is recommended to use components with large differences in vinyl molar fractions (such as 0.15% and 0.06%) to form a significantly concentrated crosslinked structure; if you need to take into account the vulcanization rate and thermal stability, you can choose components with vinyl content in the range of 0.10%~0.25% for mixing.