Where does silicone rubber come from?

To grasp the multitude of ways silicone rubber can be used, it is important to realise its origins. In this blog, we take a look at where silicone comes from to understand more about its characteristics.

Understanding the different types of rubber

To understand what silicone is you first need to know the different types of rubber available. In its purest form, natural rubber is more commonly recognised as latex and actually comes directly from a rubber tree. These trees were first discovered in South America and usage of the rubber from within them dates back to the Olmec culture (Olmec literally means “Rubber People”!).

Anything which is not formed from this natural rubber is therefore man-made and is known as synthetic.

A new substance made by mixing various materials together is called a synthetic polymer. If the polymer displays elastic properties, it is identified as an elastomer.

What is silicone made from?

Silicone is identified as a synthetic elastomer as it is a polymer which displays viscoelasticity – that is to say it shows both viscosity and elasticity. Colloquially people call these elastic characteristics rubber.

Silicone itself is made up of carbon, hydrogen, oxygen and silicon. Note that the ingredient contained within silicone is spelt differently. The ingredient silicon comes from silica which is derived from sand. The process to make silicon is complex and involves many stages. This arduous process contributes to silicone rubber’s premium price compared to natural rubber.

The silicone-making process involves extracting silicon from silica and passing it through hydrocarbons. It’s then mixed with the other chemicals to create silicone.

How is silicone rubber made?

Silicone rubber is a combination of an inorganic Si-O backbone, with organic functional groups attached.  The silicon-oxygen bond gives silicone its high temperature resistance and flexibility over a wide range of temperatures.

The silicone polymer is mixed with reinforcing fillers and processing aids to form a stiff gum, which can then be crosslinked at elevated temperature using either peroxides or polyaddition curing.  Once crosslinked the silicone becomes a solid, elastomeric material.

Here at Silicone Engineering, all our silicone materials are cured using heat which classifies our silicone products as HTV silicone or High Temperature Vulcanised. All our silicone grades are kitted, mixed and manufactured at our 55,000-sq. ft. facility in Blackburn, Lancashire. This means we have full traceability and accountability of the production process and can ensure the highest standards of quality management throughout. We currently process over 2000 tonnes of silicone rubber each year which allows us to be very competitive in the silicone market place.

What are the benefits using of silicone rubber?

The production process and material composition of silicone rubber gives it a great amount of flexibility, which is what makes it so popular for so many uses. It’s able to withstand extreme fluctuations in temperature from as low as -60°C to as high as 300°C.

It also has excellent environmental resistance from Ozone, UV and general weathering stresses making it ideal for outdoor sealing and protection to electrical components such as lighting and enclosures. Silicone sponge is a lightweight and versatile material making it ideal for reducing vibrations, stabilising joints and decreasing noise within mass transit applications – making it popular for use in environments such as trains and aircraft where customer comfort is helped by the use of silicone rubber.

This is just a brief overview of the origins of silicone rubber. However, at Silicone Engineering we understand how important it is that you understand everything about the product you are buying. If you would like to find out more to understand how silicone rubber can work in your industry then get in touch with us today.

What is EPDM?

When selecting a rubber for use, many Engineers end up needing to make a choice between selecting silicone or EPDM. We obviously have a preference for silicone(!) but how do the two match up against each other? What is EPDM and if you find yourself needing to choose between the two, how do you decide? Here is our quick-fire guide to EPDM…

What is EPDM?

EPDM stands for Ethylene Propylene Diene Monomers and it’s a type of high density synthetic rubber. It’s not as heat resistant as silicone but is able to withstand high temperatures up to 130°C. Because of that it’s used as a component within a wide variety of industries including industrial, construction and automotive. In lower temperatures, EPDM will reach brittle point at -40°C.

EPDM is also popular as an outdoor rubber as it’s resistant to weathering including acid and alkali resistance. As such, you’ll typically find it being used for things such as window and door seals or waterproofing sheets.

EPDM also has good abrasion, cut growth and tear resistance.

What more can silicone offer?

While silicone and EPDM share a number of features such as excellent environmental resistance, there are also a number of significant differences and it’s important to acknowledge these when making your purchasing decisions.

Silicone is a mix of carbon, hydrogen, oxygen and silicone and this mixture gives a number of benefits which EPDM doesn’t. Silicone is much more heat resistant, being able to withstand temperatures up to 230°C while maintaining its physical properties. What’s more, it’s also a sterile elastomer and as such is popular within the food and beverage industries. In lower temperatures silicone also exceeds EPDM and will not reach brittle point until -60°C.

Silicone is also stretchier and provides more elongation than EPDM. It can also be formulated to be just as tear resistant as EPDM. Both of these aspects make it ideal for use as vacuum membranes in machines used to produce solar panels and laminated furniture, often called vacuum forming machines.

Silicone is a more stable elastomer and as a result buyers feel that silicone is better as a more secure long-term solution because of this. Although silicone is seen as the more costly out of the two, EPDM’s lifespan is often shorter than that of silicone and therefore has to be replaced in application more often. This results in the long term cost exceeding that of silicone.

Finally, while both EPDM and silicone will swell if placed in oil for long periods of time at high temperatures, silicone has resistance to food oils at room temperature which is why it is used in food oil processing as seals and gaskets for processing machinery.

How to choose between the two?

While this short guide simply summarises some of the differences between the two the best way to determine which rubber you need is to understand the purpose of use and exact application. Identifying how you will want to use it, what conditions it will be subject to and how you need it to perform will allow you to have a much clearer view as to which rubber to choose.

Also, be sure to consider aspects such as the strength, flexibility and weight the material will need to withstand as these can also be crucial deciding factors. When you have this information our comprehensive guide to Silicone Rubber vs EPDM can provide you with the in-depth information you need to make your final determination.

If you would prefer to discuss your project requirements with one of our team then someone is always available. Call us today on 0845 421 2050.


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