Silicone vs EPDM

Jehbco manufactures products from 100% silicone.  Often, there are a range of materials to choose from for your application – is Jehbco’s silicone the right one? In this article, we’ll explore the differences between silicone and one of its competitors – EPDM.  Silicone and EPDM are both common materials for o-rings, gaskets, seals, hoses and membranes.  The two materials have many similar properties.  Which one is right for your application?  Let’s take a closer look at the differences between the two.

Silicone and EPDM both exhibit good chemical resistance, excellent weathering resistance and good temperature resistance.  However, their properties are not the same, and, depending on the conditions of the application, one will be a better choice than the other.  The table below summarises some of the key differences between the two materials.

EPDM Silicone
-50 °C to 150 °C -50 °C to 230 °C
Great compression set Excellent compression set
Excellent weather resistance Excellent weather resistance
Approx. tensile strength 14 MPa Approx. tensile strength 5 MPa
Good abrasion resistance Poor abrasion resistance
Not compatible with: oils, greases, hydrocarbon fuels, aromatic hydrocarbons, concentrated acids, halogenated solvents. Not compatible with: hydrocarbon fuels, alkalis and acids, steam over 121 °C, trichloroethylene, aromatic hydrocarbons.
Compatible with: hot and cold water, alkalis, dilute acids, steam, ketones, fireproof hydraulic fluids. Compatible with: oils, brake fluids, hot and cold water, salt water, high molecular weight chlorinated hydrocarbons, fire resistant hydraulic fluid, ozone.

Both materials are able to operate over a wide range of materials.  EPDM and silicone both maintain flexibility down to approximately -50 °C, making both materials a good choice for low temperature applications.  However, silicone can withstand temperatures almost 100 °C higher than EPDM – up to 230 °C.  For high temperature applications, silicone is the best choice.

EPDM has high tensile strength and good abrasion resistance.  While silicone has good tensile strength, its abrasion resistance is not high, and for applications involving movement and friction, EPDM may be a better choice.  Silicone can be formulated to have improved tear strength, making it an ideal choice for applications such as vacuum sheeting.

Both EPDM and silicone have excellent resistance to ozone and UV.  EPDM is not recommended for use with oils and greases. While silicone does exhibit some swelling when exposed to oils, it is rated as compatible with oils and greases and is a better choice for applications involving these chemicals.  EPDM is compatible with alkalis and dilute acids, but is not resistant to concentrated acids.  Silicone has poor resistance to alkalis and acids, making EPDM the better choice for acid and alkali applications.  Neither material is compatible with hydrocarbon fuel, but silicone is resistant to automotive brake fluids.

While both materials exhibit good compression set, silicone has less compression set than EPDM.  This makes silicone a better choice for applications requiring a long lasting, reusable seal.

While silicone outperforms EPDM in some areas, both materials exhibit good properties and the right choice will depend on your individual application.  For help selecting a material for your application, consult our website www.Jehbco.com.au and contact us with any questions.