A buyer's guide comparing SUNCHEM's primary antioxidant (1010) and secondary antioxidant (168) — how each protects polymers, when to choose one, and why they're frequently used as a complementary system.
Polymer oxidation is a chain reaction: heat and mechanical shear generate free radicals, which react with oxygen to form hydroperoxides, which in turn break down into more radicals. "Primary" and "secondary" antioxidant are functional categories describing which stage of that chain reaction a compound interrupts — not a ranking of importance.
Antioxidant 1010 is a primary antioxidant: it scavenges free radicals directly, donating a hydrogen atom to neutralize them before they can propagate further degradation. Antioxidant 168 is a secondary antioxidant: it decomposes hydroperoxides — the reactive intermediates that form earlier in the cycle — before they can break down into new radicals. Because they act on different points of the same degradation pathway, the two are complementary stabilization components rather than competing products.
| Comparison Dimension | Antioxidant 1010 | Antioxidant 168 |
|---|---|---|
| Chemical Role | Primary antioxidant (hindered phenolic type) — donates hydrogen atoms to interrupt the oxidative radical chain. | Secondary antioxidant (phosphite type) — reduces hydroperoxides to stable, non-reactive alcohols. |
| Function Mechanism | Free radical scavenging — breaks the chain reaction at the propagation stage. | Hydroperoxide decomposition — removes reactive intermediates before they generate new radicals. |
| Polymer Protection Role | Protects against long-term thermo-oxidative degradation over the polymer's service life. | Protects against processing-stage degradation — heat and shear-induced discoloration and property loss. |
| Processing Stability | Contributes moderate protection during processing; primary strength is long-term stabilization. | Provides strong melt-phase stability — color retention and viscosity control during extrusion and molding. |
| Long-Term Stability | Provides strong long-term thermal-oxidative stability across the product's service life. | Limited long-term stability alone; strongest when paired with a primary antioxidant. |
| Typical Applications | Polypropylene, polyethylene, engineering plastics, fibers, films — general-purpose long-term heat stabilization. | Same base polymer families, applied specifically at the compounding, extrusion, and molding stages. |
| Common Usage Scenarios | Used alone where processing conditions are moderate and long-term heat aging resistance is the priority. | Rarely used alone; typically combined with a primary antioxidant as part of a synergistic stabilization package. |
Chemical class: Hindered phenolic antioxidant | Role: Free radical scavenging
Antioxidant 1010 interrupts the oxidative chain reaction by donating a hydrogen atom to a free radical, converting it into a stable, non-reactive species before it can propagate further degradation. This direct action on the radical itself is why it is classified as a "primary" antioxidant.
Chemical class: Phosphite antioxidant | Role: Hydroperoxide decomposition
Antioxidant 168 works one step earlier in the degradation pathway: it reduces hydroperoxides into stable alcohols before those hydroperoxides can break down into new radicals. It does not scavenge radicals directly, but it removes a major source of new radical formation — which is why it is classified as "secondary."
Because the two compounds act on different points in the same degradation cycle, using them together addresses more of the oxidation pathway than either can alone. Antioxidant 168 reduces hydroperoxides before they regenerate radicals; Antioxidant 1010 scavenges any radicals that form regardless. In combination, this is generally described in the industry as a complementary, synergistic antioxidant system — not two competing options.
Long-term heat aging resistance is the primary concern and processing conditions are moderate (standard extrusion/molding temperatures).
Color retention and melt-phase stability during high-shear or high-temperature processing are the primary concern, and long-term aging is addressed separately or is less critical.
The application requires both processing-stage color/viscosity control and long-term service-life durability — the most common configuration in polyolefin and engineering plastics compounding.
Both antioxidants are used across PP compounding; processing-stage protection (168) and long-term heat aging resistance (1010) are both relevant depending on end application.
High-throughput PE grades benefit from 168's melt-phase color and viscosity stability; PE with long outdoor or high-temperature service life benefits from 1010's long-term protection.
Higher-temperature engineering resins are more prone to processing-stage oxidative damage, making 168 particularly relevant — often alongside 1010 for the finished part's service life.
Across extrusion, injection molding, and compounding, antioxidant selection should be driven by which stage of degradation — processing or service-life — is the greater risk for the specific application.
SUNCHEM supplies both Antioxidant 1010 and Antioxidant 168 as a manufacturer and supplier with quality-controlled sourcing and export documentation support, giving buyers a single point of contact for complementary primary and secondary antioxidant systems rather than sourcing each component separately. Our team can help evaluate which product — or combination — fits a specific processing and service-life requirement.
Antioxidant 1010 is a primary antioxidant that scavenges free radicals to protect polymers over their service life. Antioxidant 168 is a secondary antioxidant that decomposes hydroperoxides, primarily protecting the polymer during processing. They act at different stages of oxidation and are chemically distinct — 1010 is a hindered phenolic compound, 168 is a phosphite.
It depends on what needs protecting. If long-term heat aging resistance is the priority, 1010 alone may be sufficient under moderate processing conditions. If melt-phase color and viscosity stability during processing is the priority, 168 plays the larger role. Many formulations use both together — see the Buyer Decision Guide above.
Yes. Combining a primary antioxidant (1010) with a secondary antioxidant (168) is a common industry approach because the two work on different parts of the oxidation cycle. Exact dosage ratios depend on the polymer system, processing conditions, and end-use requirements — contact SUNCHEM's technical team for formulation-specific guidance.
A secondary antioxidant like 168 interrupts the oxidation cycle by decomposing hydroperoxides before they regenerate radicals. A primary antioxidant like 1010 interrupts the cycle by scavenging free radicals directly. Used together, they address oxidation from two complementary angles, which is why combined systems are widely used in polyolefin and engineering plastics compounding.
SUNCHEM's technical team can help you evaluate Antioxidant 1010, Antioxidant 168, or a combined system for your specific polymer and processing conditions.