1. Overview of MgO in NBR

Magnesium Oxide (MgO) is a commonly used alkaline activator in nitrile rubber (NBR) formulations. It mainly functions as:

• Acid acceptor

• Curing promoter

• Stabilizer

• Anti-degradation assistant

MgO effectively neutralizes acidic by-products generated during processing and vulcanization, ensuring a stable curing system and long-term product performance.

2. Key Functions of MgO in NBR

1) Neutralization of Acidic By-products

During processing and vulcanization, NBR may produce acidic substances such as organic acids or trace HCl.
MgO rapidly neutralizes these acidic components, maintaining a stable curing environment.

Benefits:

• Prevents cure retardation or scorching

• Improves cure speed and consistency

• Enhances stability of physical properties

2) Synergistic Effect with Zinc Oxide (ZnO)

MgO is often used together with ZnO to form an efficient metal soap system, significantly improving curing activity.

Benefits include:

• Faster vulcanization rate

• Higher crosslink density

• Improved heat resistance

3) Enhanced Heat, Oil, and Aging Resistance

Due to its strong alkalinity and acid-absorbing capability, MgO helps reduce rubber degradation under high-temperature or oil exposure.

Performance improvements:

• Better heat aging resistance

• Improved oil resistance (ASTM Oil No.1/2/3)

• Reduced compression set

• Extended service life of rubber products

4) Stabilization in Halogen-containing Systems

In halogenated systems, MgO is essential to absorb free HCl and prevent acid-induced degradation.

Effects:

• Prevents chain scission

• Maintains color stability

• Enhances long-term durability

3. Typical Dosage (for reference)

Actual dosage depends on the formulation and ZnO ratio.

4. Main Advantages of MgO in NBR Applications

• Accelerates and stabilizes vulcanization

• Neutralizes acidic by-products

• Works synergistically with ZnO

• Enhances heat, oil, and aging resistance

• Improves compression set

• Increases durability and long-term performance

5. Recommended MgO Grades for NBR (from Wanfeng)

PureMag-150X / PureMag-200X / PureMag-300X

Features:

• High activity and high purity

• Uniform particle size and excellent dispersion

• Strong acid-absorption capacity

• Outstanding performance as an activator and stabilizer in NBR systems

6. Typical NBR Applications Using MgO

• Oil-resistant hoses and seals

• O-rings and oil seals

• Automotive fuel-system components

• Gaskets and rollers

• General industrial oil-resistant rubber products