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 1914-1922 when the price of natural rubber rose from $0.115 per pound to as high as $1.02 per pound. Later in 1925, 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 1926, the first successful synthetic rubber, Buna, was patented by German company, IG Farben. Later on in 1931, IG Farben developed Buna-N (nitrile rubber). Mass production was of nitrile rubber was started later on in 1935. 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?
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.
Nitrile rubber is widely used in automotive and industrial areas where chemical resistance is vital – such as in fuel pumps.
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.
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.
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
|Good tear resistance||Poor weather resistance (ozone, sunlight)|
|Good abrasion resistance||Poor flame resistance|
|Good resistance to water and non-polar solvents||Inadequate for high temperatures|
|Less costly than fluoroelastomers|
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
- Steam resistant
- Resistant to weathering
- Flexible – 600% elongation and a tensile range of 500-2500 psi
Where Is EPDM Mainly Used?
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.
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.
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.
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.
Pros and Cons of EPDM
|Steam and water resistant||May be difficult to adhere to some materials|
|Good electrical resistance||Not compatible with most oils or acids|
|Remains stable across a large range of temperatures|
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