Summary

• EPDM seals are known for exceptional chemical resistance, temperature resilience, and flexibility, making them highly suitable for various industrial applications.
• Featuring cost-effectiveness, long lifespan, and minimal maintenance requirements, EPDM seals offer robust advantages in sectors like automotive, aerospace, and water treatment.
• The choice between peroxide-cured and sulfur-cured EPDM offers nuanced options for specific application needs, impacting their mechanical and chemical properties accordingly.

Introduction

The selection of appropriate sealing materials is a critical factor in optimizing performance, longevity, and safety across various industrial applications. Ethylene Propylene Diene Monomer (EPDM) has distinguished itself as a material of choice, offering an extensive array of features and advantages suitable for diverse industrial requirements. This blog comprehensively analyzes EPDM seals, elucidating their characteristic features, multifaceted benefits, and common applications. Additionally, the piece will explore variables to consider when deciding between different types of EPDM cures.

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What is EPDM?

Ethylene Propylene Diene Monomer, commonly known as EPDM, is a synthetic rubber elastomer renowned for resisting several environmental conditions. Primarily made up of ethylene and propylene, derived from oil and natural gas, EPDM also contains a diene component that serves as a cross-linking agent. This unique chemical composition gives EPDM an impressive resistance to ozone, polar substances, and hot and cold water.

Developed in the s, EPDM emerged as industries like automotive and aeronautics sought more robust materials to withstand challenging environments. Since then, EPDM has been a reliable option for various industrial applications, thanks to its outstanding mechanical properties. Notably, the material exhibits flexibility and durability, typically operating between -67°F to 257°F.

When you compare EPDM to other popular sealing materials like Buna (Nitrile) and Viton® (FKM), EPDM distinguishes itself with its superior water and weather resistance. Buna excels in oil-based applications, and Viton® is well-suited for high-temperature environments. Sill, EPDM is exceptionally versatile, with the capacity to resist moisture, ozone, and UV radiation effectively.

The manufacturing of EPDM seals often involves rubber injection molding. In this process, the raw EPDM material heats until it becomes malleable and then undergoes injection into a mold shaped like the desired seal. After cooling, the seal is extracted and goes through a curing process to achieve its final, application-ready properties.

Environmental sustainability is another area where EPDM shines. The material is recyclable and boasts a long lifespan, which means less frequent replacement and, consequently, less waste. Additionally, the manufacturing process for EPDM is relatively low in toxicity, further enhancing its position as an eco-friendly choice of synthetic rubber.

Features of EPDM Seals

The features of a material are paramount in determining its suitability for specific applications. Among the diverse range of sealing materials available, EPDM seals have a unique set of features that make them highly versatile and effective in various industrial settings.

EPDM is renowned for its exceptional chemical resistance against dilute acids, alkalines, and polar solvents like ketones and alcohols. This feature makes it invaluable for applications in chemical processing, wastewater treatment, and the pharmaceutical industry. EPDM’s chemical resistance is due to its saturated elastomeric backbone, which provides stability and inertness towards many reactive chemicals. The material’s resistance to a wide range of pH values, spanning dilute acids and alkalines, is attributed to its polar molecular structure that facilitates strong intermolecular forces, offering resistance against corrosive chemical attacks.

Temperature resilience is another notable quality of EPDM seals, stemming from its unique polymer architecture, which involves a diene monomer that allows cross-linking. This cross-linking contributes to the material’s high tensile strength and ability to withstand a broad range of temperatures, from cryogenic lows of -67°F to highs of 257°F. Where used in freezing climates or high-heat applications such as steam systems, EPDM retains its physical properties, minimizing the risk of seal failure due to thermal fluctuations.

Regarding flexibility and durability, EPDM owes its performance to its unique elastomeric nature and a high degree of polymer entanglement. Its amorphous structure allows for better free-volume distribution, resulting in enhanced flexibility. EPDM also exhibits a high fatigue resistance and low compression set due to its molecular architecture, which inherently resists abrasion, tearing, and impact.

EPDM stands out for its ability to withstand prolonged exposure to UV radiation, ozone, and extreme weather conditions. This characteristic derives from its saturation and the presence of protective antioxidants and UV stabilizers that prevent oxidative degradation. The material’s intrinsic resistance to UV radiation, ozone, and other oxidative agents stems from its non-polar nature, which limits the formation of free radicals that cause aging and material breakdown. This property makes it particularly useful for outdoor applications, like construction machinery or automotive weather stripping, where the seals regularly experience the element exposure.

EPDM’s dielectric constant and dielectric strength make it an excellent electrical insulator. The material has a low dissipation factor, and its non-polar structure minimizes free ion movement, rendering it resistant to electrical conductivity. This electrical insulation is particularly crucial in applications requiring stringent electrical isolation.

One of these less-discussed yet valuable attributes of EPDM is its color stability. Due to the absence of double bonds in its backbone, the material’s resistance to photo-oxidative degradation allows for color longevity and the ability to maintain its original hue. When combined with pigments or dyes, the material exhibits excellent colorfastness properties, making it ideal for aesthetically sensitive applications where color fidelity is essential.

Benefits of Using EPDM Seals

The extensive range of features offered by EPDM seals naturally translates into various benefits, making them a sought-after choice across multiple industries. Here, we delve into the key advantages that set EPDM seals apart from their counterparts.

• Cost-effectiveness: EPDM seals are often more cost-effective than other sealing materials like Viton® or Silicone when considering their lifespan and performance characteristics. Their resistance to environmental factors and a broad range of chemicals reduces the need for frequent replacements, adding to overall cost savings.
• Longevity in Applications: Thanks to their robust chemical and mechanical properties, EPDM seals exhibit a long service life. Their resistance to degradation from different external factors ensures that they remain effective over extended periods, reducing the overall cost of ownership.
• Minimal Maintenance Requirements: EPDM seals generally require less maintenance due to their durability and resistance to environmental conditions. This benefit translates into less downtime for equipment and reduced maintenance labor costs.
• Versatility Across Multiple Industries: The chemical, mechanical, and thermal properties of EPDM seals make them highly versatile. They find a wide application across sectors such as automotive, aerospace, water treatment, and pharmaceutical industries.
• Improved Safety Features: EPDM’s excellent chemical resistance and thermal stability enhance safety by minimizing the risk of seal failure that could lead to leaks or other hazardous conditions. The material’s insulating properties also make it a preferred choice in electrical applications for added safety.
• Environmental Benefits: EPDM’s long lifespan and recyclability contribute to its environmental benefits. Additionally, its production processes are relatively low in toxicity, making it a more sustainable option than other sealing materials.
• Ease of Installation: EPDM seals are easier to install than other types due to their flexibility and elastic properties. They can often be applied without specialized tools or adhesives, making the installation process quick and straightforward.

Common Applications of EPDM Seals

The automotive industry relies heavily on the durability and chemical resistance of EPDM seals. These qualities are crucial in automotive applications, such as cooling systems, brake systems, and air conditioning, where the seals gain exposure to many temperatures and potentially corrosive fluids. The longevity and minimal maintenance requirements of EPDM seals make them a preferred choice in automotive manufacturing, leading to more reliable and cost-effective vehicles.

Water treatment facilities also benefit from using EPDM seals. EPDM’s resistance to diluting acids and alkalines is a significant advantage in water and wastewater treatment applications. Here, seals gain exposure to chemicals like chlorine or other disinfectants. EPDM’s chemical resistance ensures the integrity of the seals, reducing the risk of leaks and improving overall plant safety.

In the pharmaceutical and food industries, the non-toxic and FDA-compliant nature of EPDM seals makes them ideal for use in various processing equipment. These industries often have stringent regulations around material safety and sanitation. The chemical stability of EPDM makes it suitable for applications that involve exposure to pharmaceutical formulations or food-grade chemicals. The seals’ longevity also ensures consistent performance, reducing replacement frequency and potential downtime.

Aerospace applications present unique challenges like extreme temperature fluctuations and the need for lightweight yet robust materials. EPDM seals are advantageous here due to their thermal resilience and low weight. They are common in hydraulic systems, fuel systems, and cabin sealing applications within aircraft. The improved safety features of EPDM, including chemical resistance and thermal stability, are especially critical in aerospace, where material failure can have catastrophic consequences.

Finally, the oil & gas industry employs EPDM seals in various capacities, such as valves, pumps, and hydraulic systems. Although EPDM is not generally resistant to hydrocarbons, specialized applications within this sector can use specific grades of EPDM. The material’s robustness against extreme environmental conditions and ease of installation are crucial in the demanding environments typically encountered in oil & gas operations.

Peroxide vs. Sulfur-Cured EPDM

When choosing EPDM seals, the key decision often involves opting for peroxide-cured or sulfur-cured variants. While both types share the core attributes of EPDM, such as excellent weather resistance and versatility across applications, the curing process can significantly impact their mechanical and chemical properties.

The creation of peroxide-cured EPDM uses organic peroxides as curing agents, resulting in a polymer structure that excels in high-temperature and chemical resistance. This cure type has stronger and more stable cross-links, contributing to higher tensile strength and superior compression set resistance. Its heightened chemical stability makes it suitable for applications that involve exposure to a broader range of chemicals such as automotive and aerospace industries.

Sulfur-cured EPDM, by contrast, uses sulfur as the curing agent, offering its own advantages. This curing method generally produces more flexible and elastic seals, qualities highly valued in construction and low-temperature applications. While not as chemically resistant as peroxide-cured EPDM, the sulfur-cured variant performs reliably against a narrower range of chemicals and is typically more cost-effective.

Comparing the two, peroxide-cured EPDM excels in harsh environments, particularly where high temperatures or broad chemical resistance is required. On the other hand, sulfur-cured EPDM is often preferred for its flexibility, making it an excellent choice for dynamic applications requiring good elongation properties. The choice between the two often boils down to specific application needs, balancing factors like chemical resistance, temperature tolerances, and mechanical properties to make an informed decision.

Conclusion

What Is The Difference Between EPDM And Nitrile Rubber?

What Is Nitrile Rubber?

Nitrile rubber is one of the most popular sealing materials. It is also known as Buna-N, Perbunan, Acrylonitrile Butadiene Rubber, and NBR. Nitrile rubber was developed as a substitute for natural rubber that would have better chemical and physical properties. Its origin can be traced back to between - when the price of natural rubber rose from $0.115 per pound to as high as $1.02 per pound. Later in , the rubber supply from Asian countries faced a shortage and the price of natural rubber reached $1.25 per pound. In response to this shortage, German and American companies started to research synthetic rubber as a potential alternative.

In , the first successful synthetic rubber, Buna, was patented by German company, IG Farben. Later on in , IG Farben developed Buna-N (nitrile rubber). Mass production was of nitrile rubber was started later on in . During World War II, Germany banned the export of nitrile rubber to UK and USA, prompting Standard Oil and other companies licensed by IG Farben to start their own nitrile rubber production.

Properties Of Nitrile Rubber

• Puncture resistant (3 times as much as natural rubber)
• Oil resistant (Most known for this)
• Temperature resistant (Generally can function in -40-degree to 226-degree F temperatures)
• Resistant to aliphatic hydrocarbons
• Good tear resistance
• Excellent adhesion to metal and rigid materials
• Good resistance to gas permeability

What Is Nitrile Rubber Used For?

Gloves

Nitrile rubber is more resistant to oils and acids, and is also stronger than other rubber variants such as natural rubber. This makes it ideal for manufacturing laboratory and medical gloves.

Fuel hoses

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Nitrile rubber is widely used in automotive and industrial areas where chemical resistance is vital – such as in fuel pumps.

Gaskets

Due to its resistance against oils and other liquids, nitrile rubber is a good choice for making industrial gaskets. Its tensile strength and abrasion resistance also make it ideal for gaskets.

Rollers

Nitrile rubber finds widespread use in the roller industry due to its resistance to oils and petroleum-based solvents, as well as its abrasion resistance and impact resistance also make it an ideal candidate for making rollers.

Plumbing materials

The water resistance of nitrile rubber makes it a good choice for making plumbing implements such as pipes, tubing, O-rings, and gaskets.

Molded and extruded products

Nitrile rubber can be molded into custom shapes for specific uses. It can be molded, extruded or calendered into parts and goods of various shapes and sizes. However, due to its relative higher cost, it is reserved for applications where oil-resistance is vital.

Pros and Cons of Nitrile Rubber

What Is EPDM?

EPDM, short for ethylene propylene diene monomer, is a type of synthetic rubber. It is used in low-slope or flat roofing applications.

In order to understand what EPDM is, we first have two identify the two major types of rubber: natural rubber, and synthetic rubber. 

Synthetic rubber is defined as ‘any elastomer that is artificially made’. In other words, it is any man-made polymer that is viscous (thick) and elastic (stretchy). It is superior to natural rubber in two major respects, thermal stability and resistance to oils and related compounds.

How Is EPDM Manufactured?

EPDM, like other synthetic rubbers, is made by polymerizing the by-products of crude oil processing. One such by-product is isoprene, which is polymerized to produce cis-1,4-polyisoprene—a synthetic version of natural rubber.

However, EPDM, like other rubbers, has poor mechanical properties. To combat this, EPDM is usually compounded with fillers (such as fumed silica) and plasticisers (such as mineral oils) in order to increase its strength and flexibility.

Properties Of EPDM

• Resistant to high temperatures
• Adaptable to low temperatures
• UV resistant
• Waterproof
• Steam resistant
• Resistant to weathering
• Flexible – 600% elongation and a tensile range of 500- psi

Where Is EPDM Mainly Used?

Auto parts

The automotive industry is where EPDM is used most. The waterproof nature and all-weather resistance of EPDM make it an ideal material for sealing the seams in vehicles. This includes door seals, window seals, trunks seals, and hood seals. Because of its durability and ability to withstand friction, EPDM is also used in the blades of windshield wipers. 

Additionally, EPDM finds use in the tubings of the water pumps, thermostats, EGR valves, oil coolers, radiators, etc. It is a favorable material to make such hoses because of its resistance to high and low temperatures, as well as its ability to accommodate various chemicals and oils without breaking down. 

EPDM linings are also sold as aftermarket accessories for vehicle owners who want to protect their cars from weather. These linings are especially RV or trailers because they are always exposed to all types of weather.

Industries

Among other characteristics, the flexibility and toughness of EPDM lend it well to being used in harsh environments such as factories and laboratories. EPDM is fairly unreactive with many low strength industry chemicals and gases, which is why it is used in things such as face masks for industrial respirators. EPDM’s low electrical conductivity also makes it suitable to be used as insulation in electrical components. EPDM is also used to make various tubings, gaskets, belts, diaphragms, grommets and geomembranes are also made using EPDM.

Construction

Roofing is one of the main application areas of EPDM. It is loved because it can withstand UV rays, hailstorms, strong winds, and other extreme conditions. 

EPDM roofing is much more common in the Northern climate areas than Southern climate areas since Northern areas are cooler.. Its heat absorption and insulation properties help to keep interiors warm and also to melt snow on the rooftops. 

A disadvantage of EPDM in roofing is that it can shrink over time, leading to leaks and costly repairs. However, if installed correctly and in the right climate, EPDM roofing can last up to 40 years.

Heating, Ventilation, Air Conditioning, and Cooling (HVAC) 

For HVAC systems to perform well and reliably, the right materials need to be used. Materials that are accessible, insert, and allow for a large temperature range, EPDM fits the bill.

Noisy air conditioning systems are a common complaint among consumers. EPDM has a density that makes it a good sound insulator. Using it within HVAC systems helps to deaden the vibrations of the motors and fans. 

EPDM is useful in cooling and heating systems that require connections to be air and water-tight, but still maintain flexibility. 

For devices that are exposed to the elements, such as air conditioning units, their damage can be prevented by using EPDM gaskets, grommets, and ductings which are resistant to UV radiation, moisture, oxidizing agents, among other environmental factors.

Water sealing

The structure of EPDM is that of tightly packed molecules. This is why it provides such good barriers against escape or passage of liquids and gases. As such it is a good seal for water and gas tanks, even ponds.

EPDM is a good alternative to metal for sealing in moisture-rich environments because it can’t rust. EPDM also doesn’t harbor microorganisms such as bacteria, fungi, or leeches. 

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Pros and Cons of EPDM

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