Silicone Melting Temperature | What You Need To Know

Silicone Melting Temperature | What You Need To Know

Lately, I have been getting many questions about silicone melting temperature.

So I wrote this article to answer some of those questions and help you learn more about this topic.

First, let’s find out if silicone really melts.

Does Silicone Melt?

Well, unlike most plastics that begin to melt at high temperatures, silicone doesn’t.

However, at temperatures above 200°C (celsius), silicone rubber slowly loses its mechanical properties and becomes brittle over time.

To answer the question more accurately, you need to consider something: Silicone vs Silicon.

Note the difference.

Silicon is a naturally occurring chemical element. It is primordial. Silicone, on the other hand, is a synthetic polymer made of siloxane, which contains silicon, oxygen and other elements.

Notably, silicone can tolerate a wide range of temperatures. It doesn’t melt. Instead, it remains solid, but only until it burns.

Silicone, a synthetic polymer, doesn’t have an exact melting point, at least not at high temperatures. Nevertheless, it’ll melt and burn at the right temperature.

Melting Temperature for Sillicone
Melting Temperature for Sillicone

As you know, silicone is considered a thermostatic elastomer. It has an extremely high resistance to heat.

This material has huge covalent bonds that are pretty strong. These bonds lose much (or all) of their strength when molten.

Their tight-mesh energy structure is not as easy to penetrate as ionic bonds. It is for this reason that silicone doesn’t melt as quickly.

Overall, silicone melts at extremely high temperatures and under the right conditions.

Melting Temperature Of Silicone Rubber

The exact melting temperature of silicone will vary depending on the type (grade) of silicone you use. What temp does silicone melt? However, the melting point generally ranges from 1000°F (537.778°C) and 2577.2°F (1414°C).

At the same time, you can use silicone for cryogenic applications. For instance, you can use silicone products in low temperatures of about -60°.

But, even before silicone reaches the melting point, the material experiences certain changes during its heating cycle.

Take for instance:

  • Below 150°C, there will be no significant changes in silicone material. It does not matter whether you subject silicone to continuous heating at this temperature.
  • At about 200°C, silicone will begin losing its elastic properties. That is, it will begin to harden and consequently become less stretchy
  • At 300°C silicone becomes harder with minimal elastic properties. However, at this temperature silicone will not melt.

Remember, these values may vary slightly depending on the silicone grade.

Working Temperature for Different Grades of Silicone

Silicone Grade Properties
General purpose silicones
  • They are suitable for high temperature applications
  • Temperature range:  high (200 to 250 °C) while low (-50 to 75 °C)
Heat stabilized silicone
  • Feature special additives which increase the working temperature
  • Highest working temperature is about 260 °C
High-temperature silicone
  • Can withstand 300 °C high temperature for intermittent applications
  • Subjecting silicone to continuous use within this temperature may cause degradation
Flame retardant silicone
  • Features additives with self-extinguishing properties
  • High working temperature is 220 °C

Additionally, the heat resistance properties of rubber is exceptional. For instance, at 150°C, most silicone rubbers do not experience any form alterations in their structures. The exception silicone rubber heat resistance properties make it perfect for most industrial applications.

At very cold temperature of -55 to -70°C, silicone does not harden. It guarantees good elasticity. In fact there are silicone grades that can withstand extremely low temperatures of below -100 °C.

Remember, these desirable temperature and heat resistance properties are due to strong covalent bonds.  A reason for silicone temperature tolerance characteristics.

Silicone Thermal Conductivity

Silicone has a low thermal conductivity. Therefore, it neither conducts nor transfers heat.

Even when you subject silicone to heat, it will remain stable in a wide temperature range. This is due to the siloxane backbone.

Factors Affecting Food Grade Silicone Melting Point

Silicon Properties
Silicon Properties

Several factors can affect the melting temperature of silicone, including:

  • Type of silicone
  • Purity of the silicone
  • Presence of additives
  • Heating time

First, it’s essential to know that there are different types of silicone, each of which has its own melting temperature. Polydimethylsiloxane, for example, has a lower melting point than polydimethylsiloxane-co-phenyl.

So pay attention to what type of silicone you use in your project. For example, silicone with a higher melting point may be necessary for a project involving extremely high temperatures.

Second, the melting temperature of silicone can vary depending on the purity of the silicone you’re using. Impurities can act as nucleating agents and lower the melting point.

Additives also play a role in the melting temperature. For example, fillers can raise the melting point, while plasticizers can lower it.

The amount of filler in the silicone can also influence the melting temperature. The more fillers present, the lower the melting temperature.

Also, the time you expose silicone to heat can affect its melting temperature. If you expose silicone to high heat for a longer time, the melting temperature will drop lower than if you expose it for a shorter time.

Measure Silicone Rubber Melting Temperature Range

One way to measure the melting point of silicone is to use a differential scanning calorimeter (DSC). This device measures the flow of heat into or out of a material when it heats or cools.

By measuring the heat flow, the DSC can determine the melting point of the silicone.

To measure the melting temperature, you first heat the material to its melting point. Then you measure the temperature at which it begins to flow.

Silicone

This method is known as the differential scanning calorimetry method, from which the measuring device gets its name.

How to Control Melting Temperature Of Silicone

There are a few ways to control the melting temperature of silicone

One way is to use a different type of silicone. Some silicones have a lower melting point than others.

Another way to control the melting temperature is to add filler to the silicone. This can lower the melting point by up to 50 degrees.

Finally, you can also change the cure time or cure temperature. This also changes the thermal conductivity of the silicone and can lower the melting temperature.

Conclusion

As you can see, there are a lot of factors that can affect the melting temperature of silicone. It is essential to consider all of these factors when choosing silicone for your project.

With a little bit of research, you should be able to find the perfect silicone for your needs.

So, there you have it. That’s all you need to know about the silicone melting temperature.

More Resources:

Silicone Manufacturing Process – Source: LegenDay

History Of Silicone – Source: LegenDay

What is RTV-1 Silicone – Source: Legenday

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