NBR rubber is generally more expensive than EPDM rubber. This is primarily due to the differences in their chemical compositions and the specific applications they are designed for.

NBR rubber, also known as nitrile rubber, is a copolymer of butadiene and acrylonitrile. It is known for its excellent resistance to oils, fats, and fuels, making it suitable for applications in the automotive, industrial, and construction industries. The presence of acrylonitrile in NBR rubber contributes to its higher cost, as the synthesis of this monomer is more complex and expensive compared to the production of EPDM rubber.

EPDM rubber, on the other hand, is a terpolymer of ethylene, propylene, and a small amount of a non-conjugated diene. It is highly resistant to heat, ozone, and weathering, making it ideal for applications in the automotive, electrical, and construction industries. While EPDM rubber offers excellent durability and resistance properties, it does not have the same level of oil resistance as NBR rubber. This difference in chemical composition and properties contributes to the price difference between the two types of rubber.

According to a report by Grand View Research, the global nitrile rubber market size was valued at USD 5.1 billion in 2018 and is expected to grow at a CAGR of 5.1% from 2019 to 2025. The higher cost of NBR rubber is attributed to its specialized properties and the complexity of its production process. In contrast, the global EPDM rubber market size was valued at USD 5.3 billion in 2018 and is expected to grow at a CAGR of 4.5% from 2019 to 2025. The lower cost of EPDM rubber is due to its simpler production process and more widespread use in various applications.

In conclusion, NBR rubber is generally more expensive than EPDM rubber due to its specialized properties and the complexity of its production process. The differences in chemical composition and intended applications contribute to the price discrepancy between the two types of rubber.