How Antioxidants Improve Polymer Stability
Why Polymers Degrade Through Oxidation
Polymer oxidation follows a chain reaction. Heat, UV radiation, mechanical shear, or metal contamination generates free radicals. These react with oxygen to form peroxy radicals, which continue the chain. Without antioxidants, this leads to yellowing, embrittlement, melt flow changes, and surface degradation.
Primary Antioxidants: Radical Scavengers
Hindered phenol antioxidants (Antioxidante 1010, 1076, 1098) donate hydrogen atoms to peroxy radicals, converting them into stable molecules and breaking the chain reaction. They are the first line of defence against oxidative degradation.
Secondary Antioxidants: Hydroperoxide Decomposers
Secondary antioxidants address hydroperoxides — the key intermediates that reinitiate radical chains if left unchecked:
- Phosphites (Antioxidante 168): Fast-acting at high melt temperatures, excellent processing stabilizers
- Thioesters (DSTDP, DLTDP): Cost-effective long-term thermal aging protection
Synergistic Systems
- Antioxidante 1010 + 168: Most widely used polyolefin system
- Antioxidante 1010 + DSTDP: Cost-effective long-term stabilization in PP/PE
- Antioxidante 1010 + 168 + HALS: Full stabilization for outdoor applications
Polymer-Specific Selection
- PP: 1010 + 168 at 0.1–0.3% combined
- Educação Física: Combined systems; confirm by OIT testing for pipe/geomembrane applications
- Engineering plastics: Grades stable at 250–300°C (Antioxidante 168 is key at these temperatures)
Perguntas frequentes
Do antioxidants provide UV protection?
No. Antioxidants address thermal oxidative degradation only. For outdoor applications, UV absorbers and HALS stabilizers must be added separately.
Contact SUNCHEM
SUNCHEM's team can help recommend the right antioxidant system for your polymer and application. Contate-nos for technical support and samples.