EPDM Rubber Extrusions: Weather Resistance and Durability

EPDM rubber extrusions are known for their exceptional weather resistance and durability. Made from ethylene, propylene, and a diene monomer, EPDM offers superior resistance to UV radiation, ozone, and extreme temperatures, making it the best choice for outdoor applications in various industries, including automotive, construction, and renewable energy. In this article, we dive into EPDM rubber extrusion and how it’s different to other types of extrusion.

Properties of EPDM Rubber Extrusions

EPDM rubber is a synthetic rubber made from ethylene, propylene, and a diene monomer, this is where it gets its name from.

• Ethylene: A colourless gas used as a primary monomer in EPDM rubber production, contributing to the polymer's backbone and providing stability and strength.

• Propylene: Another primary monomer in EPDM rubber, propylene enhances the flexibility and durability of the polymer, allowing for better elasticity and resistance to degradation.

• Diene Monomer: A secondary monomer in EPDM rubber, the diene monomer introduces unsaturation sites that allow for vulcanisation (cross-linking), improving the rubber's heat and ageing resistance.

EPDM differs from other types of rubber primarily in its superior resistance to weathering, ozone, and UV radiation, making it ideal for outdoor applications. It operates effectively across a wide temperature range (-50°C to +150°C). Unlike natural rubber, EPDM is less susceptible to degradation from environmental exposure. Compared to nitrile rubber, which excels in oil and fuel resistance, EPDM is not suited for such applications but offers better weather resistance. Silicone rubber withstands extreme temperatures but is more expensive. Neoprene provides balanced properties but lacks the same level of UV and ozone resistance as EPDM.

Applications in Different Environments

Automotive Industry

1. Weatherstripping: used around doors and windows to prevent water, dust, and air from entering the vehicle.

2. Seals and gaskets: employed in engine compartments, boot seals, and other parts where a durable, flexible seal is required.

3. Hoses: coolant hoses, vacuum hoses, and other fluid transfer systems due to EPDM's resistance to heat and chemicals.

4. Window and Windscreen seals: to ensure a tight seal and prevent leaks, while also reducing noise and vibration.

Construction Industry

1. Roofing membranes: used in flat roofing systems for waterproofing due to its resistance to UV, ozone, and weathering.

2. Window and door seals: provides airtight and watertight seals around windows and doors.

3. Expansion joints: used in concrete and masonry structures to absorb thermal expansion and contraction, preventing cracks.

4. Pipe seals and gaskets: in plumbing systems to prevent leaks and ensure tight joints.

Industrial Applications

1. Electrical insulation: used for insulating cables and wires due to its good dielectric properties and resistance to environmental factors.

2. Belts and conveyor systems: for moderate abrasion resistance and flexibility in conveying systems.

3. Tubing and hoses: in various industrial fluid transfer applications where resistance to water, steam, and chemicals is essential.

4. Vibration dampening: in machinery and equipment to reduce noise and vibration.

HVAC (Heating, Ventilation, and Air Conditioning)

1. Duct seals: used to seal joints in HVAC ductwork, preventing air leaks and ensuring efficient airflow.

2. Gaskets and seals: in air conditioning units, furnaces, and other HVAC equipment to prevent leaks and enhance energy efficiency.

Marine Industry

1. Hatch seals and door seals: used in boats and ships to provide watertight seals.

2. Window and windscreen seals: for watertight and airtight seals that can withstand harsh marine environments.

3. Cable insulation: to protect electrical cables from water and environmental exposure.

Aerospace

1. Door and window seals: in aircraft to provide airtight seals and reduce noise.

2. Environmental seals: around various components to protect against environmental factors like temperature extremes and UV radiation.

Consumer Products

1. Appliance seals: used in washing machines, refrigerators, and other household appliances for sealing and insulating purposes.

2. Sporting goods: in equipment like grips and padding due to its durability and flexibility.

3. Garden hoses: due to its resistance to weathering, UV, and flexibility.

Agriculture

1. Irrigation systems: seals and gaskets in irrigation systems to prevent leaks and ensure efficient water delivery.

2. Farm equipment: seals and hoses used in various agricultural machinery for fluid transfer and environmental protection.

Renewable Energy

1. Solar panel seals: used around solar panels to provide airtight and watertight seals, protecting the panels from environmental exposure.

2. Wind turbine seals: in wind turbines to prevent the ingress of dust, water, and other contaminants.

Benefits Over Other Rubber Types

In summary…

• EPDM (Ethylene Propylene Diene Monomer) is best for applications requiring weather, ozone, and UV resistance. It is commonly used in automotive weather stripping and seals, roofing membranes, and outdoor applications.

• Nitrile is best for applications involving oils and fuels. It is commonly used in fuel hoses, gaskets, and seals where oil resistance is crucial.

• Silicone is excellent for high and low-temperature applications. It is commonly used in medical devices, food-grade applications, and seals exposed to extreme temperatures.

• Neoprene is good all-around performance with balanced properties. It is commonly used in automotive and industrial gaskets, hoses, and weather-resistant applications.

• Natural Rubber is best for applications requiring high tensile strength and flexibility but limited in weather and chemical resistance. It is commonly used in tyres, vibration mounts, and seals.

Manufacturing Process of EPDM Rubber Extrusions

Let’s take a look at the manufacturing process for EPDM.

1. Raw Material Preparation

• The primary raw material is the EPDM polymer, which is sourced in pellets or bales. Fillers like carbon black, clay, or silica are added to enhance properties such as strength, durability, and resistance.

• Plasticisers and oils are used to improve the processability and flexibility of the rubber.

• Sulfur or peroxide-based curing agents are added to facilitate the vulcanisation process.

• Antioxidants, UV stabilisers, and other chemicals are added to improve the performance and longevity of the EPDM rubber.

2. Mixing

• The raw materials are fed into an internal mixer where they are thoroughly mixed under controlled temperature and pressure to form a homogeneous rubber compound.

• The mixed compound is then passed through a two-roll mill to further blend the ingredients and improve the consistency. This step also helps in cooling the material and preparing it for extrusion.

3. Extrusion

• The compounded EPDM rubber is fed into an extruder, which consists of a barrel and a screw. The screw conveys the material through the barrel, where it is heated and pressurised.

• The heated rubber is forced through a die, which shapes the rubber into the desired profile. The die design determines the cross-sectional shape of the extruded product.

• The extruded rubber is then cooled to maintain its shape and prepare it for the next stage. Cooling can be achieved using air, water, or a combination of both.

4. Vulcanisation (Curing)

In this process, the extruded rubber is passed through a continuous vulcanisation system, such as a microwave or salt bath, where it is exposed to heat to initiate the curing reaction. This cross-links the polymer chains, giving the rubber its final properties. For some applications, the extruded profiles may be cured in an autoclave, a pressurised vessel where the rubber is exposed to steam or hot air for a specified time.

5. Finishing

• The extruded and cured rubber profiles are cut to the required lengths using automated cutting machines.

• The finished products are inspected for quality, ensuring they meet the required specifications and standards.

• Depending on the application requirements, additional post-processing steps may include trimming, punching holes, or adding adhesive backing.

Here is a more concise comparison focusing on the specific differences of EPDM rubber compared to other rubber types in each step of the manufacturing process:

Future Developments in EPDM Rubber Technology

Advancements in EPDM rubber technology are driving innovations across various industries, from automotive sealing systems and renewable energy solutions to building and construction, furthering performance, durability, and sustainability.

Automotive Sealing Systems

Automakers like BMW and Tesla have been integrating advanced EPDM rubber extrusions into their vehicle sealing systems. These seals are designed to provide superior weatherproofing, noise reduction, and durability. The use of multi-material co-extrusion techniques, where EPDM is combined with other materials like thermoplastic vulcanisates (TPVs), enhances the performance of these seals by providing better flexibility and sealing properties.

Renewable Energy Solutions

Companies such as First Solar are using EPDM rubber extrusions in their solar panel mounting systems. The EPDM components are utilized for gaskets and edge seals that ensure water resistance and UV protection, prolonging the life of solar panels. The extrusions are designed to withstand harsh environmental conditions while maintaining their flexibility and sealing capabilities, ensuring optimal performance of the solar installations.

Find out about the rubber extrusions we make or take a look at our blog where we demystify all types of rubber extrusion, looking at different materials, processes, and applications.