EPDM rubber is one of the most widely used synthetic elastomers in industry. The following article from Thai Duong Plastics will help you better understand the features, technical properties, and advantages of EPDM compared to other types of rubber, so you can choose the most suitable material for your specific application.
Overview of EPDM Rubber (Chemical-Resistant Rubber)
EPDM (Ethylene Propylene Diene Monomer) is a synthetic rubber belonging to the M-class group under ASTM D-1418 classification. The M-class indicates that EPDM’s main polymer chain is saturated. It is a copolymer of ethylene and propylene, with a small amount of diene added to allow for crosslinking during vulcanization. Thanks to its saturated backbone, EPDM offers high stability against environmental factors such as UV rays, ozone, and oxidation.
This material was first researched in the 1950s and became commercially available in the 1960s. During the oil crisis, EPDM became popular as it could replace petroleum-based materials in the construction and automotive industries.
See also: What is Rubber?
Composition and Technical Properties of EPDM Rubber
EPDM is a non-polar synthetic elastomer made from three types of monomers (ethylene, propylene, and a small amount of diene monomer such as ENB, DCPD, VNB, etc.). Ethylene and propylene form the main polymer chain, while the diene component enables crosslinking during vulcanization.
The molecular structure of EPDM features a saturated backbone, giving it excellent resistance to oxidation and environmental degradation. This is also why EPDM is widely used in outdoor applications and situations that demand outstanding weather resistance.
Vulcanization can be achieved using two common systems: sulfur and peroxide. Sulfur vulcanization is suitable for standard applications and is cost-effective, while peroxide vulcanization offers higher heat and chemical resistance, making it ideal for harsh environments or demanding technical requirements.
5 Key Physical Properties
The physical specifications below highlight EPDM’s performance in typical mechanical and temperature conditions:
- Hardness: Ranges from 40 to 90 Shore A, allowing for adjustment based on required elasticity.
- Tensile strength: Can reach up to 25 MPa depending on compounding, ensuring excellent mechanical stability.
- Elongation at break: From 300% to 600%, reflecting excellent elasticity and recovery after deformation.
- Density: Between 0.9 and 1.3 g/cm³, optimizing product weight while maintaining strength.
- Heat resistance: Performs reliably from -50°C to 150°C, suitable for a wide range of climates and industrial temperatures.
Typical Chemical Properties
EPDM rubber provides excellent chemical resistance, especially to polar solvents such as acetone, alcohol, glycol, organic acids, and dilute alkalis. This makes it highly durable in mild chemical environments, steam exposure, and outdoor atmospheres.
EPDM also exhibits strong resistance to UV rays, ozone, and oxidation. However, it is not compatible with non-polar hydrocarbon compounds, mineral oils, gasoline, or lubricating greases. In these environments, the material tends to swell, deform, and lose mechanical properties.
Common Applications of EPDM Rubber
Thanks to these properties, EPDM rubber is widely used in various sectors such as:
- Construction: Roofing membranes, expansion joints, waterproofing materials, and outdoor rubber flooring.
- Automotive: Door seals, coolant hoses, vibration dampers, and expansion joints.
- Chemical and water treatment industries: Seals for tanks, industrial valves, and components exposed to highly corrosive environments.
- Food industry: White EPDM rubber compliant with FDA standards is used in equipment and piping that come into contact with food and drinking water.
- Electrical industry: Thanks to its excellent insulation properties, EPDM is used for cable jacketing and electrical insulation pads in devices.
Additionally, EPDM is found in household goods, sporting equipment, heat-resistant tapes, and load-bearing components used outdoors.
Notes on Processing EPDM Rubber
Although EPDM is highly resistant, it is more challenging to process than some other rubbers. During mixing or extrusion, EPDM tends to wrap around rollers and adheres poorly to fabrics or metals. This requires proper processing techniques and the use of suitable adhesives to ensure strong bonding between layers.
In injection molding and compression molding, vulcanization temperature and time must be carefully controlled. For peroxide-cured EPDM, avoid using in uncoated metal molds prone to corrosion, as peroxide compounds can cause strong oxidation reactions.
Advantages of EPDM Rubber Compared to Other Rubbers
Compared to other synthetic rubbers, EPDM stands out for its wide temperature range, weather resistance, and resistance to polar chemicals. Unlike NBR, which is oil-resistant but poor against ozone and UV, EPDM performs exceptionally well outdoors and in mild chemical exposures.
Compared to silicone, EPDM is less expensive and offers greater mechanical strength for applications requiring tensile or impact resistance. While FKM (Viton) excels in oil resistance, EPDM has the advantage of higher elasticity and lower production cost.
EPDM rubber is a versatile synthetic material with outstanding mechanical, chemical, and environmental performance. To learn more about the effective use of EPDM in industrial rubber molding, contact Thai Duong Plastics for detailed consultation.