Understanding Elastomers: Silicone Rubber
Elastomers are polymers that have a coiled structure which makes them highly elastic: elastomer is a portmanteau of “elastic” and “polymer”. This material has important properties that makes it suitable for use in all different industries, including healthcare, construction, aerospace engineering and transportation.
In this guide, we’ll discuss the different types of elastomers and explore some of the most common industry uses. With a comprehensive understanding of their properties and characteristics, you’ll be able to make a more informed decision on which is the best option for your specific industrial requirements.
Types of elastomers
Elastomers can be divided into two categories: saturated and unsaturated. There are important distinctions between the two which makes them suitable for different applications.
Molecular Structure of Elastomers – Saturated
The primary characteristic of saturated elastomers is their stability when exposed to external factors such as temperature, ozone, oxygen and radiation. Because the polymer chains are fully saturated, a reaction to these conditions will only occur under very specific circumstances. Since saturated elastomers are less reactive, they’re more resilient to environmental differences. Chemically, polymer chains in saturated elastomers contain carbon atoms that are connected by single bonds, resulting in lower reactivity.
Examples of saturated elastomers and their common uses:
- Silicone rubber: seals, gaskets, electrical insulation
- Polyacrylic rubber: automotive components, vibration dampening
- Fluorosilicone rubber: aerospace components and other parts that may come into contact with fuel based oils or petroleum
Molecular Structure of Elastomers – Unsaturated
The molecular structure of unsaturated elastomers differs from saturated in that they contain carbon-carbon double (or triple) bonds. The unsaturated bonds in these elastomers makes them more chemically reactive than saturated alternatives. Unsaturated elastomers can be cured by sulphur vulcanisation: this is the process where individual polymer chains become cross-linked to create a stronger, more durable material. When it comes to industrial applications, unsaturated elastomers are more commonly used because they’re often stronger.
Examples of unsaturated elastomers and their common uses:
- Butyl rubber: tyres and sporting goods
- Natural rubber: medical devices and children’s toys
- Polybutadiene: footwear and automotive parts
Properties and Benefits of Elastomers
It’s important to note that different types of elastomers will have their own unique properties. For example, a silicone rubber (a saturated elastomer) is able to withstand far higher temperatures than butyl rubber (unsaturated). This highlights how crucial it is to understand the individual properties of different types, to ensure you’re implementing the right applications for each material.
✔ Elasticity and flexibility. The key differentiator between elastomers and other types of polymers is their elasticity. Due to their unique molecular structure, elastomers can withstand immense stress when stretched out and can return to their original shape when this force is removed. For the best performance, unsaturated elastomers need to be cured to enhance elasticity.
✔ Melting points. Saturated elastomers have extremely high melting points. There are lots of factors that can impact the actual melting point, such as the time exposed to extreme temperatures. When exposed intermittently, silicone rubber can withstand temperatures of around 300ºC without permanent deformation. The same applies to lower temperatures, with no physical or chemical changes occurring as low as -60ºC.
✔ Durability. When used in high-pressure environments, materials need to be extremely durable and resilient in harsh conditions. Compared to lots of other manufacturing materials, elastomers are incredibly durable and generally have high tear resistance, ensuring better performance and longevity over time.
✔ Chemical resistance. Lots of elastomers exhibit good chemical resistance, but there is a high level of variability depending on the type of material and the chemical it’s exposed to.
When it comes to silicone, it’s highly capable of maintaining performance when in contact with a range of acids, but is prone to swelling when exposed to oil or petroleum. On the other hand, nitrile rubber offers strong resistance to lots of industrial fluids like oil, grease and alcohols, which is why it’s commonly used in the auto
motive sector and in industrial machinery.
Market Sectors and Applications
As mentioned above, it’s important to select the right elastomer with the most suitable properties for each specific purpose. While there are some shared traits, two elastomers can vary drastically in their physical characteristics and applications.
From everyday products to the most technical industrial components, uses for elastomers are incredibly varied. Here are three of the most common:
- Automotive. Perhaps without realising it, we come into contact with elastomers almost every day. In our cars, the most common uses for elastomers are in tyres, windshield wipers, seals and gaskets.
- Rail and Mass Transit industry due to its high flammability resistance and low smoke emissions, including HVAC gaskets, electronic enclosure seals, and vibration dampening in the flooring systems. These applications make it a key component in maintaining both passenger comfort and safety.For more information around how silicone is used in rail applications , read our case study on the New York Subway.
- Medical devices and healthcare. A huge number of medical devices contain elastomers to utilise their many useful properties: oxygen masks, catheters, implants, prosthetics and IV systems are several examples. They’re also commonly used in personal protective equipment, such as latex gloves and face masks. During the pandemic, silicone rubber had a key role in protecting patients, healthcare professionals and the general public. Read our case study on the use of silicone in face shields.
- Construction. Owing to its robust chemical composition and versatility, a range of elastomers are used throughout the construction industry. One of their primary uses is in seals and gaskets which in turn protects buildings from environmental elements. Elastomers also have a crucial role in vibration management, enhancing the safety credentials of structures.
Finding the right material for the job
It’s clear that elastomers offer a range of benefits to a number of different projects and industries. However, with so many variations, it’s important you understand which is best tailored to meet your specific needs. Elastomers are present in both the most cutting-edge innovations and simple everyday items; they can offer solutions to complex business problems, so having this understanding could give you a clear competitive edge.
For all your silicone requirements, get in touch with our team of specialists today.