A Guide To Know The Difference Between Silicone Rubber & EPDM !!

EPDM and silicone are two commonly used rubbers in industrial applications, with silicone acting as a general use rubber while EPDM is more specialized. Both are sometimes confused with one another. What’s the difference between EPDM and Silicone and when should you use one over the other? 

EPDM stands for Ethylene Propylene Diene Monomer. It’s a synthetic rubber popular in construction and automotive industries. Silicone, as Polydimethylsiloxane is commonly called, is an inorganic polymer, and based on quartz sand. It’s used in applications that range from automotive and aerospace to food and beverage.

How are EPDM and Silicone alike?

It’s easy to see why there’s some confusion. Both EPDM and silicone:

• Offer excellent weathering resistance
• Are excellent as electrical insulators
• Maintain flexibility down to around -50°C/-58°F
• Stand up to some chemicals
• To a varying degree, have great compression set
• Are popular as water-system seals, O-rings, hoses and membranes
• Can be finished to an extremely smooth surface
• Are flame retardant
• Withstand high temperatures, to a varying degree

That’s where their similarities end, however. Let’s take a look at the advantages that each material offers.

The Advantages of EPDM

• EPDM has a stable, saturated polymer backbone structure, which gives the material its advantages. 
• Of all the EPDM rubber is the most water resistant, which is why it’s so popular for outdoor applications and is often used as a roofing material.
•  EPDM stands up to harsh weather conditions such as sleet and snow.
• Another reason for its use outdoors, particularly in construction, is its excellent resistance to abrasions and tears and ability to stand up to the degrading effects of weathering, ozone and UV ray exposure.
• EPDM also offers good electrical resistance. Its chemical properties make it especially suitable for electrical insulation and gaskets. 
• It resists polar solvents, and not just water, but also acids, alkalis, and phosphate esters. 
• EDPM does a great job of withstanding steam and low and high temperatures, though silicone can take on even higher temperatures.
• The material has a low compression set, so it won’t lose much resilience over prolonged pressure.

The Advantages of Silicone

• Silicone is food safe. It’s an incredibly versatile material, thanks to its chemistry and the many ways that it can be modified. Consequently, it offers vast possibilities.
• Perhaps its most appealing characteristic is its ability to take on extremely high temperatures, which is why it’s especially popular for masking applications. Manufacturers will all give different melting points based on their experience and own criteria, but generally silicone can stand up to 232°C/ 450°F. Compare that to EPDM’s 148°C/300°F.
• Like EPDM, Silicone has outstanding resistance to ozone and weathering.
• Silicone can be modified to stand up to water, as seen by such products as silicone sealants. 
• On the plus side, Silicone is resistant to automotive brake fluids, while EPDM is not. Silicone also has an excellent compression set, which is even lower than EPDM.

At a glance: EPDM vs Silicone

Where will you find EPDM?

Wherever water and abrasion resistance are the first priorities, but EPDM isn’t only for outdoor applications; its water resistance makes it an excellent seal for plumbing applications too. Here are the most popular applications for EPDM and how it’s used.

1. 1. Used in HVAC:  To Supports thermal expansion and resists vibration. Example – Grommets that isolate vibrations while providing an airtight dust and watertight seal.
   2. Used in Enclosures:  To provide good resistance to polar solvent. Example- Sealing gaskets are used on metal sheets, providing an extra seal while isolating vibrations and keeping enclosures free of dust and water.
   3. Used in Automotive: Bonds quickly with metal, offers a strong barrier against the weather, and reduces force of engine’s vibrations. Example- Flexible top bubble gaskets can be pressed by hand or automation & Dual-hard self-adhesive gaskets for areas that need to stand up to daily rigorous demands.
   4. Used in Masking: As it is resistant to chemicals. Example- Tight seal of Easy pull masking caps prevents paint ingress as well as quick to apply and remove.
   5. Used in Construction: Water and abrasion resistant. Example- Single flipper gaskets create a weather seal around vents, doors and other openings. Flexible profiles can be applied by hand. Used as a roofing membrane, especially for low-sloped buildings.
   6. Consumer Appliances: Protects against vibrations. Example- Washing Machine Foot with Shore A 70 rubber base to prevent appliances from moving due to vibration.

Where will you find Silicone?

Silicone properties include elongation, good thermal conductivity, and high resistance to very high temperatures make it a versatile material. Here are just some of the applications where it’s often used.

1. Used in HVAC: Excellent compression set. Example- Fan mounts with high elongation provide excellent shock and vibration protection.
2. Used in Masking: Resistant to extremely high temperatures, which allows for blasting, powder coating, e-coating, anodizing, plating and wet painting. Example- High-temperature plugs provide excellent sealing for plating, anodizing, spray  painting and other finishing applications. Masking pull plugs for threaded and plain through holes  material is flexible  enough to allow for variation in sizes that need masking. Versatile masking straight caps fit over studs, pins or tube ends. Plugs mask threaded and non-threaded holes. Range of colors possible for easy identification.
3. Used in Electronics: Excellent stability against mechanical and electrical shock and vibration. Example- USB and RJ Plugs protect entry from dirt and moisture ingress.
4. Used in Industrial: Flame retardant, flexible and protects from radiation. Example-  Fire protection sleeves are self-extinguishing, Mouse tails plug very small holes with tight, sealed fit, Rotary dampers include silicone among other materials to provide damping resistance.
5. Used in Cable Management: Outstanding thermal range and elongation. Example- Cable straps can be stretched and wrapped around bundles.

Both EPDM and silicone have their merits and drawbacks, depending on the application they’re used for. If you’d like more information on these and other types of rubber, you can check out our blog- https://www.kesaria.com/blog/what-are-the-different-types-of-rubber-material/