EPDM vs Silicone
Both are rubbers and both are sometimes confused with one another. What is the difference between EPDM and Silicone? When should you use one over the other?
First of all, the most basic. EPDM is an abbreviation for ethylene propylene diene monomer. This is a synthetic rubber that is very popular in the automotive and construction industries. Silicone, commonly called polydimethylsiloxane, is an inorganic polymer based on quartz sand. Its applications range from automobiles and aerospace to food and beverages.
What are the similarities between EPDM and silicone?
It is easy to understand why there is some confusion. EPDM and silicone:
Has excellent weather resistance
Are excellent as electrical insulators
Maintain flexibility around -50°C/-58°F
Resist some chemicals
To varying degrees, there are large compression sets
Are popular as o-rings, hoses and membranes
Can be finished to an extremely smooth surface
Is a flame retardant
Can withstand different degrees of high temperature
However, this is where they are similar. Let’s take a look at the advantages of each material.
EPDM
Advantages of EPDM
EPDM rubber has a stable, saturated polymer backbone structure, which gives this material an advantage.
Among all rubbers, EPDM is the most water resistant, which is why it is so popular in outdoor applications and is often used as a roofing material. EPDM rubber can withstand severe weather conditions such as sleet and rain.
Another reason for its outdoor use, especially in construction, is its excellent abrasion resistance and tear resistance, and its ability to withstand the degradation effects of weathering, ozone and ultraviolet exposure.
EPDM rubber also provides good electrical resistance. Its chemical properties make it particularly suitable for electrical insulation and gaskets. It is resistant to polar solvents, not only water, but also acids, bases and phosphate esters. EDPM does a good job of withstanding steam and low and high temperatures, although silicone can withstand higher temperatures.
The degree of compression set of this material is very low, so it will not lose too much elasticity under long-term pressure.
Advantages of silicone
Silicone is food safe. It is a versatile material, thanks to its chemical properties and various methods that it can be modified. Therefore, it offers huge possibilities.
Perhaps its most attractive feature is its ability to withstand extremely high temperatures, which is why it is particularly popular in masking applications. Manufacturers will give different melting points based on their experience and their own standards, but usually silicone can reach 232°C/450°F.
Like EDPM, silicone has excellent resistance to ozone and weathering. Most manufacturers classify its water resistance as excellent, but its water swell resistance is generally poor. Silicone can be modified to resist water, as seen in products such as silicone sealants. Otherwise, the strength of EPDM in this area is lacking. Silicone does not have good acid and alkali resistance, which means that if it rains, the rubber will be damaged and become useless.
On the positive side, silicone is resistant to car brake fluid, while EPDM is not. Silicone also has excellent compression set, which is even lower than EPDM rubber.
