At Jehbco, we manufacture our products exclusively from pure silicone. Silicone is a type of polymer known as an “elastomer” – these polymers are stretchy or elastic. For many applications, it is not quite clear which elastomer is the best to use. Probably the most well known elastomer is natural rubber, commonly known as latex. In this article, we’ll look at the properties of silicone and natural rubber and discover when you might choose one or the other.
Natural rubber, with the chemical name polyisopropene, is produced naturally from the sap of the rubber tree. Silicone, on the other hand, is a synthetic material. While both materials are elastomers, they differ in many of their properties. Some of these properties are summarised in the table below.
|-50 °C to 80 °C||-50 °C to 230 °C|
|Excellent compression set||Excellent compression set|
|Poor weather resistance||Excellent weather resistance|
|Approx. tensile strength 25 MPa||Approx. tensile strength 5 MPa|
|Excellent abrasion resistance||Poor abrasion resistance|
|Not compatible with: ozone, strong acids, fats, oils, greases, hydrocarbons.||Not compatible with: hydrocarbon fuels, alkalis and acids, steam over 121 °C, trichloroethylene, aromatic hydrocarbons.|
|Compatible with: hot and cold water, weak acids, alcohols, ketones, aldehydes.||Compatible with: ozone, oils, brake fluids, hot and cold water, salt water, high molecular weight chlorinated hydrocarbons, fire resistant hydraulic fluid.|
Both natural rubber and silicone are able to operate at very low temperatures – down to -50 °C. However, silicone is able to operate at much higher temperatures than natural rubber. Natural rubber starts deteriorating at 80 °C and melts at 120 °C. Silicone is able to be formulated to operate up to 230 °C. Silicone also has significantly better flame resistance than natural rubber. For high temperature applications, silicone is certainly the better choice.
Neither silicone nor natural rubber have good resistance to hydrocarbon fuels and lubricants. However, silicone exhibits a wider chemical resistance than natural rubber, often making it the better choice for chemical sealing applications. The choice of material in chemical applications will depend however on the exact chemicals that the material will come into contact with. Both materials are used in applications such as piping and tank lining.
Natural rubber exhibits much higher tensile strength, tear strength and abrasion resistance than silicone. It is used in high wear applications such as tyre treads and conveyor belts. Silicone has relatively low abrasion resistance, and in applications where a part will be subjected to abrasion and wear, natural rubber is a better choice.
Silicone has excellent resistance to weathering and UV, and is often found in outdoor applications such as door and window seals. In contrast, natural rubber weathers very quickly and is not suited to outdoor applications. If your application involves exposure to the elements, silicone is the better choice.
For help selecting a material for your application, please contact us with any questions.