Silicone is a versatile polymer that is successfully used in many fields: from construction and industry to medicine and cosmetology. It is chosen for its high thermal resistance, flexibility, waterproofness, and good insulating properties. However, even such a reliable material can be subject to degradation under certain conditions. In this article, we will explore what exactly degrades silicone, why this happens, and how to protect products made from this material.
Why silicone is considered resistant but not invulnerable
Silicone consists of a silicon-oxygen (Si–O) backbone and organic groups (for example, methyl groups). Thanks to this structure, it has:
- Thermal resistance: able to withstand high and low temperatures.
- Elasticity: remains flexible even at extreme temperatures.
- Chemical inertness: resistant to most household chemicals, water, and ozone.
At the same time, silicone is not absolutely “invulnerable.” Some aggressive substances and environmental factors can cause damage, which over time will lead to degradation or loss of elasticity.
Main factors that degrade silicone
1. Aggressive chemicals
Silicone is most often degraded with prolonged contact with certain types of compounds. Among the hazardous substances:
- Concentrated acids (for example, sulfuric, nitric, oleum).
- Strong alkalis (for example, concentrated sodium or potassium hydroxide).
- Some solvents (toluene, benzene, white spirit can negatively affect, especially at high temperatures or prolonged contact).
- Chlorinated organic compounds (trichloroethylene, dichloromethane).
These substances can attack the silicon-oxygen bonds or organic side groups, leading to structural disruption of silicone and gradual degradation.
2. Ultraviolet radiation
UV rays usually have a detrimental effect on many materials. Silicone is relatively resistant to ultraviolet light; however, with prolonged and intense exposure to UV radiation:
- The surface of silicone may lose transparency or yellow (if it is a transparent material).
- The product becomes more brittle, may crack, and lose elasticity.
3. Mechanical damage
Friction, strong pressure, constant bending—all of these wear down silicone over time:
- Microcracks appear.
- Sealing ability decreases (especially critical for silicone seals in plumbing, windows, etc.).
- Resistance to stretching decreases.
4. Improper storage conditions
Silicone products are sensitive to environmental conditions. Storing in an environment with excessive humidity, under direct sunlight, or near sources of aggressive vapors (for example, paints, solvents) can shorten their lifespan.
Table: Typical substances and their effects on silicone
Below is an example of which substances are relatively safe for silicone and which can cause damage:
| Substance | Effect on silicone | Degree of danger |
|---|---|---|
| Water (regular, distilled) | Practically no effect | Low |
| Weakly concentrated acids (acetic) | Minor effect with short contact | Low |
| Food oils | Almost no effect | Low |
| Vegetable and animal fats | Possible slight swelling | Low/Medium |
| Alcohols (ethanol, isopropanol) | Usually safe in moderate concentrations | Low |
| White spirit, gasoline, kerosene | Can lead to swelling and gradual degradation | Medium/High |
| Strong alkalis (NaOH, KOH in concentrate) | Destroy the structure of silicone | High |
| Concentrated acids (H2SO4, HCl) | Degrade silicone with prolonged contact | High |
| Chlorinated hydrocarbons (trichloroethylene) | Severe degradation | High |
| Ozone, intense UV radiation | Accelerate aging and brittleness | Medium/High |
How to reduce the risk of silicone degradation
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Avoid contact with aggressive substances. If a silicone product is to be used in conditions involving solvents or concentrated acids, it is advisable to choose special silicone grades designed for such purposes.
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Protection from UV rays. If possible, use or store silicone in places where it will be less exposed to direct sunlight. Some manufacturers add UV stabilizers to the silicone composition.
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Proper storage. Keep silicone products in a dry, cool, and dark place, away from heat sources and chemical vapors.
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Control mechanical load. If a silicone part is subjected to constant pressure or friction, it is advisable to regularly check it for wear or install special gaskets to reduce friction.
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Use silicone with appropriate additives. Some grades contain additional components that enhance resistance to high temperatures, UV rays, or aggressive environments. Choose a material that suits your operating conditions.
Different types of silicone for different conditions
Not all silicone is equally resistant. Manufacturers offer:
- Thermal-resistant silicones: withstand extremely high temperatures (up to 300 °C and more).
- Chemically resistant silicones: have additives that protect against alkalis, acids, or solvents.
- Medical silicones: specially designed for contact with the human body; they are strictly tested for inertness to tissues and biological fluids.
- Silicones with UV filters: have additional resistance to sunlight, thus retaining properties longer outdoors.
Before purchasing silicone, it is advisable to check the technical documentation and specifications to ensure that the chosen type is suitable for your conditions.
Frequently Asked Questions (FAQ)
1. Can household chemicals (soaps, detergents) damage silicone?
The vast majority of household products contain weakly concentrated alkaline or acidic components that usually do not damage silicone under normal usage conditions. However, if the product is very aggressive or concentrated, prolonged contact may cause structural damage to the material.
2. How quickly does silicone degrade under direct sunlight?
The degree of damage depends on the intensity of UV radiation and the type of silicone. Regular silicone may start to lose elasticity and yellow within a few months of active sun exposure. Specially modified silicones can withstand years without significant deterioration of properties.
3. How to check if silicone is safe for food?
Pay attention to certifications (for example, FDA in the USA or similar in other countries) and the “food grade” labeling. Such products are specifically tested for harmful impurities and are suitable for contact with food.
4. Can already damaged silicone be repaired?
If silicone is chemically degraded, restoring its structure is practically impossible. Mechanical damage can sometimes be “patched” with fresh silicone sealant, but this is only a temporary measure. It is best to replace the damaged part with a new one.
5. What is the average lifespan of a silicone part?
The lifespan depends on the operating conditions (temperature, sunlight, chemicals) and the quality of the silicone itself. Usually, high-quality silicone parts can last from 5 to 10 years, and sometimes even longer.
Conclusions
Silicone is an extremely useful and versatile material; however, like any substance, it has its weaknesses. Knowing what degrades silicone will help protect your silicone parts from premature wear and damage. Avoid contact with strong acids and alkalis, protect the material from excessive ultraviolet light and mechanical loads, and choose the appropriate type of silicone for special conditions. Proper use and care of silicone ensure its long and reliable service.