Silicone vs EPDM. What is Difference?

EPDM and silicone are two frequently utilized rubber materials in various industrial applications. Silicone is widely used as a general-purpose rubber, whereas EPDM is more specialized. In this discussion, we will explore the fundamental characteristics of EPDM and silicone rubber, along with their similarities and differences. This information will assist you in understanding which type of rubber is more suitable for specific applications.

What is Silicone?

Silicone, also referred to as polysiloxane, is widely recognized for its remarkable flexibility and resistance to extreme temperatures. In addition to these properties, silicone also exhibits flame resistance, hypoallergenic characteristics, gas permeability, chemical inertness, and nonstick properties. Silicone rubber is classified as an elastomer, which is an elastic polymer featuring an inorganic silicon-oxygen backbone connected to organic molecules. The manufacturing process involves extracting silicon from silica, subjecting it to hydrocarbons, and blending the resultant material with chemicals to produce silicone rubber.

However, it’s important to note that silicone is not resistant to steam, hydrocarbon fuel, alkalis, acids, trichloroethylene, or aromatic hydrocarbons. Silicone finds widespread application in various sectors including electronics, industrial settings, aerospace industry, construction projects, automotive manufacturing, medical field, consumer products, and HVAC systems.

What is EPDM?

EPDM rubber, also known as Ethylene Propylene Diene Monomer, is widely preferred for various outdoor and challenging environment applications due to its excellent resistance to water, heat, cold, weather conditions, ozone, UV rays, steam, electricity, and abrasion. EPDM is composed of a chemically saturated backbone of polymethylene, connected by single bonds. However, it does have certain limitations when it comes to resisting oil, grease, hydrocarbon fuel, concentrated acid, and halogenated solvents. EPDM is commonly utilized in roofing, plumbing, HVAC systems, and automotive applications.

How are EPDM and silicone alike?

It is understandable why there can be some confusion between EPDM and silicone, as they share several common characteristics:

  • Excellent resistance to weathering.
  • Effective electrical insulators.
  • Retain flexibility even at low temperatures, reaching approximately -50°C/-58°F.
  • Can withstand certain chemicals.
  • Display varying degrees of impressive compression set.
  • Widely used for water-system seals, O-rings, hoses, and membranes.
  • Capable of achieving an exceptionally smooth surface finish.
  • Flame retardant properties.
  • Can tolerate high temperatures to different extents.

However, beyond these shared qualities, EPDM and silicone diverge in their distinct advantages. Let’s delve into the specific benefits offered by each material.

The pros and cons of EPDM

The Pros of EPDM

EPDM possesses a stable and saturated polymer backbone structure, which contributes to its unique advantages.

Among all rubber materials, EPDM exhibits the highest level of water resistance, making it a preferred choice for outdoor applications and commonly used as a roofing material. EPDM demonstrates exceptional durability against harsh weather conditions, including sleet and snow.

Another key reason for its widespread use in outdoor settings, particularly in construction, is its remarkable resistance to abrasions, tears, and the deteriorating effects of weathering, ozone, and exposure to UV rays.

EPDM also offers favorable electrical resistance properties, making it highly suitable for applications such as electrical insulation and gaskets. It exhibits resistance not only to water but also to acids, alkalies, and phosphate esters. EPDM effectively withstands steam and functions well under both low and high-temperature conditions, although silicone can tolerate even higher temperatures.

Additionally, EPDM boasts a low compression set, meaning it retains its resilience even under prolonged pressure.

The Cons of EPDM

It is important to avoid using EPDM in conjunction with oils, greases, hydrocarbon fuels, concentrated acids, or halogenated solvents. Additionally, it is worth noting that EPDM typically has a shorter lifespan compared to silicone. Therefore, depending on the specific application, EPDM may require more frequent replacement.

The pros and cons of Silicone

The Pros of Silicone

Silicone is considered food-safe and is an incredibly versatile material, thanks to its unique chemistry and the various ways it can be modified. As a result, it offers a wide range of possibilities and applications.

One of its most notable characteristics is its exceptional ability to withstand extremely high temperatures, making it particularly popular for masking purposes. While melting points may vary based on manufacturers and their specific criteria, silicone generally remains stable up to 232°C/450°F, in contrast to EPDM’s limit of 148°C/300°F.

Similar to EPDM, silicone exhibits outstanding resistance to ozone and weathering. Most manufacturers rate its water resistance as excellent, although its resistance to water swell is typically poor. Silicone can be modified to enhance its water resistance, as demonstrated by products like silicone sealants. However, it falls short of EPDM’s strength in this particular area. According to Polymer Solutions, an independent materials testing lab in the U.S., silicone “does not possess good acid and alkali resistance,” which means that exposure to rain can potentially damage and render the rubber ineffective.

On the positive side, silicone demonstrates resistance to automotive brake fluids, whereas EPDM does not. Silicone also showcases excellent compression set properties, which are even better than those of EPDM.

The Cons of Silicone 

Although silicone exhibits good tensile strength, it generally has a poor level of abrasion resistance. It is worth noting that silicone can be formulated to enhance its tear resistance. However, it is important to avoid using silicone in situations where it will encounter steam temperatures exceeding 121°C/249°F, hydrocarbon fuels, alkalis, acids, trichloroethylene, and aromatic hydrocarbons.

What’s the Difference Between EPDM and Silicone?

Silicone vs EPDM: Application and Uses

Both silicone and EPDM find a wide range of applications, but they are not interchangeable in every role. Here are examples where either silicone or EPDM can be equally suitable:

Automotive Industry: Silicone and EPDM are commonly used in the automotive sector due to their stability and high-temperature resistance. They are both capable of withstanding intense weather conditions, ultraviolet rays, and ozone, which are potential hazards in this industry.

Building and Construction Industry: EPDM and silicone are utilized in applications such as door and window seals, gaskets, O-rings, and hoses. Their elastic properties, flexibility, and durability make them ideal choices for these purposes.

Electronics: Both silicone and EPDM serve as good insulators in electronics. They are employed in applications such as gaskets and electrical insulators for power delivery cables.

See more: Silicone For Automotive 

See more: Silicone for Building Construction

See more: Silicone for Electronic

In addition to these shared applications, silicone has exclusive areas where it is commonly used:

Aerospace: Silicone plays a vital role in the aerospace industry due to its high tensile strength and temperature resistance. It is extensively utilized in critical components, including protective coatings for circuit terminals, sealants, encapsulants, engine components, thermal protection, sensors, adhesives, and fuel tank coatings.

Food/Beverage: Silicone finds widespread use in the food and beverage industry due to its stability at high temperatures and resistance to damage from most chemicals. As the production of food requires strict safety measures to prevent contamination, silicone is an ideal material for storing and handling food and beverage products.

EPDM also has specific areas where it can be applied:

HVAC: EPDM is commonly employed in the heating, ventilation, and air conditioning (HVAC) industry. Its low electrical conductivity, vibration reduction capabilities, and ability to accommodate thermal expansion make it suitable for applications such as grommets, drain tubes, and gaskets.

Consumer Appliances: EPDM is utilized to reduce noise and vibration in consumer appliances that generate significant amounts of noise. It helps improve the overall performance and comfort of these appliances.

Silicone vs EPDM: Recycling and Sustainability

While silicone can be recycled, it necessitates a specialized recycling plant as conventional methods are not effective. In contrast, EPDM is considerably easier to recycle. The reuse of EPDM materials contributes to waste reduction and minimizes the demand for manufacturing new raw materials. Moreover, EPDM can be recycled by breaking down the material into smaller compounds, which can then be utilized in the production of rubber mats, running tracks, and similar applications.

Silicone vs. EPDM: Cost

There is no easy answer when comparing the cost of silicone rubber and EPDM. Both types of materials have a variety of prices, depending on the quality and quantity of the product. In general, silicone rubber is generally more expensive than EPDM, but there are many factors that can affect the price of either material.

It is important to note that cost is not the only factor to consider when choosing materials. The suitability of the material for a particular application should be the primary consideration. With that said, let’s take a closer look at the cost comparison of silicone rubber and EPDM.

This article presented silicone and EPDM, explained what they are, and discussed the properties and applications of each. To learn more about silicone and EPDM, contacA1 Silicones

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