Silicone rubber is famous for how well it handles extreme hot and cold, staying strong and flexible in temperatures that would melt or weaken most other materials.
This rare combination of heat and cold resistance is why silicone is trusted in industries like dairy, medical, automotive, aerospace and food processing; anywhere materials need to perform reliably in tough environments.
So how does silicone do it? The secret lies in the tiny building blocks of its structure.
The Secret is in the Structure: Si–O vs C–C Bonds
Most everyday rubbers are made from carbon atoms linked together in long chains. This is called a carbon–carbon (C–C) backbone and, while it works fine in mild conditions, it starts to break down when things get hot.
Silicone rubber is different. Its backbone is made from silicon and oxygen atoms (Si–O) instead of carbon. That one change makes a big difference, it gives silicone its unusually strong resistance to heat, cold and weathering.
1. Stronger Bonds = Better High-Temperature Stability
Think of the bonds in rubber like the links in a chain. The stronger each link, the more force (or heat) it can handle before snapping; or the stronger its heat resistance.
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The bond between silicon and oxygen (Si–O) is much stronger than the bond between two carbon atoms (C–C).
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In technical terms:
Si–O bond energy ≈ 444 kJ/mol
C–C bond energy ≈ 348 kJ/mol
That extra strength means silicone has greater heat resistance because it takes more energy to break the bonds between its atoms. When something heats up, its atoms start to vibrate. If the vibrations get strong enough, they can shake the material’s structure apart but in silicone, the bonds are so strong that this shaking doesn’t do much damage, even at high temperatures.
As a result, silicone rubber:
- Doesn’t melt or soften easily, even at temperatures above 200°C
- Keeps its shape under pressure and heat
- Doesn’t give off toxic fumes or break down like some plastics
This makes it perfect for hot environments like steam sterilisation, engine parts, ovens or any system that deals with heat and pressure.
2. Flexible and Functional in Freezing Temperatures
Silicone doesn’t just resist heat, it also performs really well in the cold, often staying flexible at temperatures as low as –60°C (and sometimes even colder).
Most rubbers become stiff and brittle when frozen. That’s because, at low temperatures, their molecules stop moving freely and the material locks up, like water turning to ice. This can cause cracking, shrinking or total failure in seals and tubes.
But silicone stays soft and rubbery. Why?
- The structure of Si–O bonds allows the material to move and bend, even when temperatures drop.
- Silicone has a very low glass transition temperature (Tg) – this is the point where a rubber goes from flexible to hard and glass-like. Silicone’s Tg is much lower than most other rubbers, so it keeps its elasticity far below freezing.
Why is the Tg so low? It’s because of how silicone is built:
- Its Si–O backbone is more flexible than the carbon-based chains in most rubbers, allowing more movement at low temperatures.
- The side groups on silicone (usually small methyl groups) don’t tangle up or stick together. This keeps the chains free to move instead of locking up; so the material doesn’t “freeze stiff” the way other rubbers can.
That means:
- It stays soft and stretchable, instead of going rigid
- Seals keep their grip and shape, reducing the risk of leaks or cracks
- It works reliably in cold-chain logistics, cryogenics, outdoor machinery and winter vehicles
In short: silicone stays “rubbery” when other materials freeze and stiffen up.
3. Resistance to Thermal Oxidation
Heat isn’t the only thing that damages rubber; oxygen can be just as destructive, especially at high temperatures.
Many rubbers are made from organic (carbon-based) materials, and when they’re exposed to heat and air, the oxygen reacts with the carbon chains. This process is called thermal oxidation, and it causes the material to:
- Harden and lose flexibility
- Crack, blister or discolour
- Break down much faster over time
Silicone resists this problem far better. Why?
- Its inorganic Si–O backbone doesn’t react with oxygen the way carbon-based chains do.
- The bonds are more stable, even in the presence of heat, air, ozone or UV light.
That means silicone:
- Doesn’t chalk, fade or flake when exposed to sunlight or outdoor air
- Keeps its softness and flexibility through repeated heating cycles
- Lasts longer in high-temperature or weather-exposed applications
In simple terms: silicone doesn’t “rust” the way organic rubbers do when exposed to heat and oxygen. That makes it ideal for long-term use in environments where other materials would start to break down.
4. Wide Operational Temperature Range
Because silicone handles both heat and cold so well, it has one of the widest working temperature ranges of any rubber.
Most standard silicone rubbers can perform reliably from around –60°C to +200°C, and they don’t just survive at those extremes, they keep working properly without cracking, melting or losing their shape.
Some specially formulated silicones can go even further:
- Down to cryogenic temperatures (–100°C or below)
- Up to +250°C or even +300°C, depending on the curing method and additives used
So why is this range so wide?
- The Si–O bonds stay strong under heat and flexible in the cold
- Silicone doesn’t go brittle at low temperatures (unlike many plastics)
- And it doesn’t soften or burn at high temperatures (unlike many rubbers)
This ability to stay stable across such a wide range makes silicone perfect for systems that heat up and cool down regularly, or that need to work in both freezing and high-heat conditions.
From factory floors to freezing lorries, ovens to engine bays, silicone stays consistent when other materials fail.
Common Applications That Rely on Silicone’s Heat Resistance
Thanks to its resistance to heat, cold and oxidation, silicone rubber is used in industries where failure is not an option.
Here are just a few places where its temperature resistance makes a real difference:
- Dairy and food production: Silicone tubing is perfect for systems that need to handle hot cleaning fluids (like CIP systems), cold storage and the hygienic transfer of food products.
- Pharmaceutical and medical equipment: It holds up during repeated steam sterilisation without breaking down or contaminating fluids; essential for safe, sterile environments.
- Automotive and transport: You’ll find silicone in engine bay seals, turbocharger hoses, and air intake systems; places exposed to extreme heat and temperature shifts.
- Industrial machinery: Used in heated rollers, ovens, HVAC systems and other equipment where materials need to stay functional during thermal cycling.
- Outdoor and weather-exposed systems: Silicone seals and enclosures keep working even in freezing winters or strong sunlight, without cracking, chalking or becoming brittle.
Trust Silclear for Heat- and Cold-Resistant Silicone Products
At Silclear, we’ve been formulating high-performance silicone products for nearly 40 years. Our materials are trusted across demanding industries, from dairy and pharma to automotive and heavy industry, for one simple reason: they work where others fail.
Whether you need tubing that can handle steam sterilisation, seals that won’t crack in the cold or mouldings that stay stable at 200°C and beyond, we can help. Call us on +44 (0)1425 610700, email info@silclear.com or enquire below.
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