There are three kinds of silicic hydroxyl groups on the surface of silica. This is not the result of my experiment. The result of human research is that the structure (hydrogen bond) should be the kind of isolated, highly active silyl. The huge amount of hydrogen bonds here is caused by nano-sized powders. If it is micron-sized silicon micropowder, the amount is too small and almost no structure. When this silanol of silica is blocked or isolated in some way, the structuring is reduced, and if it is sufficiently closed or isolated, structuring will not occur. This is the result of my experiment and the result of many people's experiments. This process, usually called so-called white carbon black, is called "hydrophobic white carbon black". Although I use hydrophobic white carbon black in business, I think this title is wrong, at least not scientific. . The reason is that hydrophobic silica (does have external hydrophobicity), the same kind of hydrophilic white carbon is used as raw material, but different treatments, although the hydrophobicity can be exactly the same, when added to silicone rubber, it does not necessarily have Anti-structural effect. That is to say, as a technician of silicone rubber, it is not said that as long as hydrophobic silica is used, an anti-structural product can be obtained.

Structured, can be controlled by different hydroxyl groups by blocking the hydroxyl groups, isolating or adding suitable additives. The complete blocking of the hydroxyl group by a chemical reaction can indeed eliminate the structuring phenomenon. Isolation, such as adding a lot of white oil, can also eliminate structuring. Additives, such as low molecular weight hydroxy silicone oils, can delay structuring (sufficient addition or long-term unstructured). These measures select one or several combinations according to product requirements.

In the industry, when adding rubber, the addition of silazane is an effective method for blocking silanol. To achieve complete sealing, a large amount of addition is required, the cost is high, the post-treatment is troublesome, and the mechanical properties of the glue may be Have a negative impact. Add a lot of white oil, only suitable for certain products. At present it is more economical to add low molecular weight hydroxy silicone oil (why is a short chain? Generally 5 chain links, this problem is very interesting, you can try it yourself), or a hydro alkoxysilane hydrolyzate, diphenyl dihydroxy silane Wait. Even with the addition of water, the alcohol has a certain anti-structuring effect.

There is a saying that structuring may contain chemical bonds, based on the phenomenon that the structured glue can continue to be used after rework, but there is a certain gap between performance and structure. I believe that after structuring, due to the huge hydrogen bond between the silica and the polysiloxane, the polymer entanglement between the polysiloxane, the training requires great shear force and a certain temperature, local Huge friction (localized high temperatures) can cause the polysiloxane chain to break and degrade, and it is not surprising that the properties change. Although structuring is inevitable when refining rubber, the structuring that we usually focus on refers to the phenomenon that occurs within a few months of storage under normal temperature and normal temperature and very mild conditions. From the structure of the raw rubber, which group has the possibility of chemical reaction with white carbon black under normal temperature and normal temperature conditions? You can say that silica is chlorine-rich and acidic. As long as a very small amount of amine is added, structuring should not occur. So far, no one has obtained anti-structure by adding amine or adjusting silica to neutral. Chemical products, so structuring can only be a huge hydrogen bond.

Low molecular polysiloxane (not referred to herein as a hydroxyl or alkoxy terminated, but a methyl or vinyl group that is only inert to silica), no structural phenomena are observed, or to a lesser extent, very Obviously related to the entanglement of polymer chains.
Therefore, I believe that the structuring is first of all the role of silica and raw rubber, followed by the entanglement of the raw rubber polymer to strengthen this effect.