Butyl Rubber vs. EPDM

Attribute	Butyl Rubber	EPDM
Chemical Structure	Isobutylene and Isoprene	Terpolymer of Ethylene, Propylene, and a Diene Monomer
Temperature Range	-40°C to 130°C	-50°C to 150°C
Weather Resistance	Good	Excellent
Chemical Resistance	Good	Excellent
Permeability	Low	Higher than Butyl Rubber

Introduction

Butyl rubber and EPDM (Ethylene Propylene Diene Monomer) are two popular types of synthetic rubber used in various industries. Both materials have unique properties that make them suitable for different applications. In this article, we will compare the attributes of Butyl rubber and EPDM to help you understand their differences and choose the right material for your specific needs.

Chemical Composition

Butyl rubber is a copolymer of isobutylene and isoprene, which gives it excellent impermeability to gases. On the other hand, EPDM is a terpolymer of ethylene, propylene, and a diene monomer, which provides it with superior resistance to heat, ozone, and weathering. The different chemical compositions of Butyl rubber and EPDM result in distinct physical and mechanical properties that make them suitable for specific applications.

Physical Properties

Butyl rubber is known for its excellent resistance to gas permeability, making it ideal for applications where airtight seals are required. It also has good resistance to heat, aging, and weathering, making it suitable for outdoor applications. On the other hand, EPDM has superior resistance to heat, ozone, and weathering, making it a popular choice for roofing membranes, automotive seals, and weatherstripping.

Mechanical Properties

Butyl rubber has good flexibility and low compression set, making it suitable for applications where sealing and vibration isolation are important. It also has good tear resistance and elongation properties, making it durable and long-lasting. In comparison, EPDM has excellent tensile strength, abrasion resistance, and elasticity, making it ideal for applications where durability and weather resistance are crucial.

Chemical Resistance

Butyl rubber has good resistance to acids, alkalis, and polar solvents, making it suitable for applications where chemical resistance is important. However, it is not recommended for use with oils, fuels, and hydrocarbons, as it can swell and degrade over time. On the other hand, EPDM has excellent resistance to ozone, UV radiation, and weathering, making it a popular choice for outdoor applications where exposure to the elements is a concern.

Temperature Range

Butyl rubber has a temperature range of -40°C to 130°C, making it suitable for applications where a wide range of temperatures is expected. It has good resistance to heat and cold, making it ideal for use in HVAC systems, automotive seals, and gaskets. In comparison, EPDM has a temperature range of -50°C to 150°C, making it suitable for applications where high temperatures and weather resistance are required.

Applications

• Butyl rubber is commonly used in applications such as tire inner tubes, pharmaceutical stoppers, and sealants.
• EPDM is widely used in applications such as roofing membranes, automotive seals, and weatherstripping.

Conclusion

In conclusion, Butyl rubber and EPDM are two versatile materials with unique properties that make them suitable for a wide range of applications. While Butyl rubber is known for its excellent gas impermeability and aging resistance, EPDM stands out for its superior heat resistance and weathering properties. By understanding the differences between Butyl rubber and EPDM, you can choose the right material for your specific needs and ensure the success of your project.