What Is The Difference Between EPDM And Natural 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 500-2500 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. 

What Is Natural Rubber?

Natural rubber is an elastic substance obtained from the latex sap of trees. Around 20,000 species of plants produce latex, but only 2,500 species have been found to contain rubber in their latex. 99% of the natural rubber we use is extracted from a tree called Hevea brasiliensis. Latex is the milky liquid that some plants ooze when you cut them. Malaysia, Indonesia, and Thailand are some of the leading producers of natural rubber.

Rubber is very important in daily life as it is used in the manufacture of thousands of products e.g., tires, gloves, shoes, toys, etc. 

How Natural Rubber Is Made

Rubber is harvested from trees in the form of latex in a process known as ‘tapping’. This process involves making incisions in the bark of the tree and collecting the sticky latex in vessels. 

In order to get the maximum amount of latex flow, tapping is usually done early in the morning when the pressure of the plant cells is highest. Once the ltex flow stops, the collected liquid is poured into containers. These containers should be made of plastic or aluminum, not copper, brass or iron.

The collected latex can be stored for up to 3 hours safely. After that the latex starts to coagulate. Pre-coagulation of the latex will affect the quality of the final rubber product.

Once harvested, the liquid latex is then mixed with a coagulation agent, such as formic acid. This causes the cohesion of rubber particles, resulting in a mass of rubber, and leaving behind a watery solution.

This block of rubber can then be pressed mechanically to flatten it into a rubber sheet. The sheets of rubber can then be washed and dried.

Alternatively, the raw latex can be mixed with synthetic rubber in various proportions to make different blends of rubber.

Properties Of Natural Rubber

• Good processability
• Excellent elastic properties
• Good tensile strength
• High elongation
• Good tear resistance
• Good wear resistance
• Heat build-up in the dynamic stress is very low. Little dissipation factor.
• Excellent cold resistance
• Good electrical insulator
• Due to the non-polar properties of natural rubber, it shows high resistance to water and acids.

What Is Natural Rubber Used For?

To make hydrophobic gear

Rubber has good water and chemical resistance that makes a suitable material for making raincoats, diving gear, water tank liners, etc.

To make items that withstand friction

The hardiness of rubber and its resistance to abrasion is why it is used to make items such as vehicle tires and machinery belts, and pipes that carry thick abrasive fluids.

To make items that can hold gases

Rubber is a good candidate for making gas pipes, balloons, and balls due to it’s relative impermeability to air and gas.

To make electricity-safe gear and items

Rubber is a good electric insulator. This is why it is used to make protective gloves and shoes.

Pros and Cons of EPDM

PROS	CONS
It is very durable. EPDM roofing for example can last 30-50 years with little maintenance.	May be difficult to adhere to some materials. The inert nature of EPDM means it does not react with and therefore may not bond very well to some materials.
Resistant to harsh conditions EPDM i various forms is resistant to weather, UV, chemicals, rot, abrasion, etc.
Relatively eco-friendly. EPDM is recyclable. It’s durability also ensures it is not being constantly replaced and sent to the landfills. It is also very compatible with green roofs and solar paneled roofs.

Pros and Cons of Natural Rubber

PROS	CONS
It is strong and flexible Natural rubber is one of the most flexible type’s of rubber. It also exhibits good tensile strength and tear resistance.	Less resistant than EPDM Natural rubber performs worse than EPDM when exposed to chemicals and oils. It may also not be the best option for surfaces that require maximum resistance to weather, ozone, oxygen or heat.
Less odor. Natural rubber has less of the ‘rubber smell’ than synthetic rubber.	Higher cost of raw materials Cultivating rubber tress and harvesting the latex is a demanding and time consuming process. It is costlier than the manufacturing of synthetic rubber.

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