In many industrial fields such as the chemical industry and pharmaceuticals, materials are often exposed to extreme chemical environments and face the erosion of chemical substances such as strong acids and alkalis, and organic solvents. As a widely used polymer material, the tolerance of silicone rubber in extreme chemical environments has received much attention. In-depth research on the chemical resistance of silicone rubber and the formulation of effective protection strategies are crucial for ensuring the safe and stable operation of relevant industrial equipment.

The erosion of silicone rubber in a strongly acidic environment mainly stems from the action of hydrogen ions. In a strong acid solution, hydrogen ions can attack the silicon-oxygen bonds (Si-O) in the molecular chains of silicone rubber. When the silicon-oxygen bonds break, the molecular chains degrade, leading to a decrease in the mechanical properties of silicone rubber, such as a reduction in hardness and a weakening of tensile strength. For example, in some chemical pickling processes, if ordinary silicone rubber is used as the pipeline sealing material, after long-term contact with a strong acid solution, the sealing parts are prone to phenomena such as swelling and cracking, which can lead to leakage problems. To improve the tolerance of silicone rubber in a strongly acidic environment, researchers have introduced acid-resistant groups, such as fluoroalkyl groups, into the molecular chains of silicone rubber through chemical modification. The strong electronegativity of fluorine atoms can enhance the stability of the molecular chains and effectively resist the attack of hydrogen ions. Experiments have shown that the service life of silicone rubber modified in this way is significantly extended in a strong acid environment such as concentrated sulfuric acid.
A strongly alkaline environment can also cause damage to silicone rubber. Hydroxide ions can react with the silicon atoms in the silicone rubber molecules, destroying the molecular chain structure. Under high-temperature and strong-alkali conditions, this reaction is more intense. In the synthesis process of some alkaline drugs in the pharmaceutical industry, if the rubber sealing parts of the reaction equipment use silicone rubber that is not resistant to alkalis, it is very likely to age and harden in an alkaline environment and lose its sealing performance. To solve this problem, researchers have developed new alkali-resistant silicone rubber formulations. By adjusting the cross-linking density of the silicone rubber and selecting special additives, the ability of the silicone rubber to resist hydroxide ions is enhanced. At the same time, a layer of alkali-resistant protective coating is applied to the surface of the material to further prevent the contact between hydroxide ions and the silicone rubber molecules and improve its durability in a strongly alkaline environment.
Organic solvents are also common challenges that silicone rubber encounters in industrial applications. Different types of organic solvents have different mechanisms of action on silicone rubber. Non-polar organic solvents such as toluene and xylene are likely to cause swelling of silicone rubber. This is because there is an interaction between the silicone rubber molecules and the organic solvent molecules, resulting in an increase in the distance between the molecular chains and an expansion in volume. Polar organic solvents such as ethanol and acetone may react chemically with the silicone rubber molecules, destroying their structure. During the production process of paints and coatings, the silicone rubber parts in the equipment frequently come into contact with organic solvents. If the materials are not properly selected, the performance is extremely likely to deteriorate. To enhance the tolerance of silicone rubber in organic solvents, on the one hand, the molecular structure can be optimized to increase the regularity and compactness of the molecular chains and reduce the intrusion of organic solvent molecules; on the other hand, surface treatment technology can be used to form a dense protective film on the surface of the silicone rubber to prevent the contact between the organic solvents and the silicone rubber matrix.


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