Secondary Antioxidants/Preventative Antioxidant

Secondary / Preventive Antioxidants

Secondary antioxidants, also known as preventive antioxidants, play a critical role in controlling oxidation after it begins. Rather than stopping free radicals directly, these additives decompose oxidation byproducts—especially hydroperoxides—before they can generate new radical species and accelerate degradation.

Nexolent Solutions’ secondary antioxidants are designed to enhance high-temperature stability, reduce sludge and varnish formation, and extend the effective life of primary antioxidants. Commonly used in lubricants, polymers, heat transfer fluids, and specialty formulations, they are essential for maintaining cleanliness and long-term performance in demanding operating environments.

Secondary antioxidants are most effective when used in combination with primary antioxidants, creating a synergistic stabilization system that delivers both immediate protection and long-term resistance to oxidative stress. This balanced approach helps preserve viscosity, reduce deposit formation, and extend service intervals under continuous thermal exposure.

Secondary antioxidants don’t stop radicals directly—they decompose oxidation byproducts (especially hydroperoxides) before those byproducts turn into new radicals.

What they do

• Break down hydroperoxides into non-reactive species

• Reduce heat- and oxygen-induced degradation

• Extend the effectiveness of primary antioxidants

Best at

• High-temperature processing

• Long-term thermal stability

Common examples

• Phosphites

• Phosphonites

• Thioesters