It is a question Silicone Engineering get asked frequently by engineers and designers who are looking for an exact temperature point where silicone rubber will start to degrade in application.
In the majority of cases there isn’t a definitive answer that our experts can give without discussing further about the environment that the silicone will be situated and the temperature(s) the material will be exposed to.
Silicone rubber, unlike the majority of other rubbers, can withstand extreme temperatures way above 200°C and down to as low as -60°C without deforming. However, one aspect determines what actual temperatures silicone can really withstand and that is TIME – The length of time the silicone is exposed to extreme temperatures determines its lifespan and performance in application and this is a very important factor when specifying rubber materials into applications.
Of course, Silicone Engineering can only speak for our grades of silicone but lets give an example; If a silicone gasket made from our high temperature grade kSil™THT is exposed to temperatures up to 300°C for intermittent periods, we can confidently say that our silicone has been tested to withstand this degree of heat for short intermittent periods and will maintain it’s physical properties. However, if an engineer informed us that the gasket will be applied in an environment where this temperature was at a constant 300°C then we would advise that the silicone would most likely degrade over a shorter life span so other material options may need to be considered.
The same scenario applies with our general purpose silicone grades. The material has been tested to withstand continuous temperatures of 230°C which in most cases is suitable for many high temperature applications. However, we also know that this grade will perform well at higher temperatures of 250°C for again intermittent periods, so the question ‘time of exposure’ to these temperatures needs to be estimated before we can advise on a suitable grade of silicone to use at high temperatures.
Therefore, when understanding silicone or any other elastomer used in high/low temperature environments, the period of exposure that the rubber will experience at a certain temperature is the crucial factor when trying to answer ‘What Temperatures Can Silicone Rubber Withstand’.
What we do know is that any applications exposed to continuous temperatures over 150°C will most likely require a silicone rubber to allow for efficient performance and longer life span. This is where Silicone Engineering can provide silicone solutions for many industry sectors and applications.
How hot can silicone get before it melts?
The first thing you will notice is that silicone doesn’t melt due to temperature alone!
For example, if heated up to 150°C you would see very little change in the silicone, even if held at this temperature for a very long time, At 200°C the silicone will slowly become harder and less stretchy with time, and if the silicone was heated up to a temperature beyond 300°C, you would quickly see the material become harder and less stretchy in a very short time, due to such extreme temperature conditions but it would not melt.
Special grades are available to further increase silicones already naturally high resistance to heat such as our silicone grade THT which can be used intermittently at temperatures up to 300°C. Silicones auto ignition temperature is approximately 450°C, service at such a high temperature is not recommended.
If you have another question you would like to ask one of our silicone experts, why not go to the Ask the Experts page to submit a question.