Regarding stearic acid
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May I ask whether adding stearic acid to silicone rubber can reduce its hardness, whether it acts as a release agent during extrusion, and whether it has an impact on the physical properties of the product?
Stearic acid is used in the plastics industry as a plasticizer, stabilizer, and lubricant.
I think it serves a filling purpose, but the amount shouldn’t be too much
Stearic acid should not be used in the processing of silicone rubber, as it reduces the vulcanization efficiency of OP and affects the vulcanization of the products. If stearic acid must be used, stearates such as calcium stearate can be considered as a substitute. If the poster wants to enhance the demolding effect, it’s better to add a small amount of silicone oil; too much of it should not be used as it can affect the physical properties. If the poster wants to change the hardness, they should consider reducing the amount of reinforcing agent or mixing in low-hardness silicone rubber. This post was last edited by Chengzheng on 2009-2-5 09:29.]
Rubber industry: Stearic acid plays an important role in the synthesis and processing of rubber. Stearic acid is a vulcanization activator widely used in natural gums, synthetic rubbers, and latex, and can also be used as a plasticizer and softener. Stearic acid is used as an emulsifier in the production of synthetic rubber. In the manufacture of foam rubber, it can act as a foaming agent, and it can also be used as a release agent for rubber products.
In thermoset molding materials, hard acid derivatives are mostly used.
Stearic acid has plasticizing properties and can also improve the vulcanization of rubber.
A small amount of stearic acid does not reduce hardness; it can instead help with demolding. However, too much should not be used, as this will result in excessive smoke during processing, pores forming in the product, and slow leakage of stearic acid from within the product, which affects its mechanical properties.
In the rubber industry, zinc oxide and stearic acid are generally used as activators; in silicone rubber, it is better not to use them, as they affect vulcanization!
Taking things out of context can be deadly. Stearic acid and zinc oxide are used as activators in sulfur vulcanization systems, and they have a slight effect of improving demolding and plasticity; but the original poster is referring to silicone rubber – don’t tell me you’re using sulfur to vulcanize silicone rubber! :lol