How Antioxidant 168 Improves Thermal Stability in Plastics?

During high-temperature processing, plastics can undergo oxidation, leading to discoloration, reduced mechanical strength, and shortened service life. To counter this, manufacturers use specialized antioxidant chemicals that protect polymer integrity. One of the most effective solutions is Antioxidant 168, known by its chemical name tris(2,4-di-tert-butylphenyl) phosphite. Classified under CAS No 31570-04-4, this hydrolytically stable phosphite processing stabilizer plays a vital role in preventing process-induced degradation. Its ability to react with hydroperoxides formed during polymer autoxidation ensures thermal stability, long-lasting performance, and consistent product quality

Understanding Antioxidant 168

Antioxidant 168 (CAS 31570-04-4) is a hydrolytically stable phosphite processing stabilizer widely used in polymer manufacturing. Its chemical name is tris(2,4-di-tert-butylphenyl) phosphite, with the molecular formula C₄₂H₆₃O₃P and a molecular weight of 646.9 g/mol. Available in both powder and granule forms, it appears as a white, free-flowing material with a melting range of 183–186°C.

In contrast with primary antioxidants which chelate free radicals directly, Antioxidant 168 functions as a secondary antioxidant in polymers and reacts with autoxidized hydroperoxides. This reaction avoids polymer chain degradation and sustains the physical, mechanical, and visual characteristics of the final output. Owing to the high thermal stability and non-discolouring character of it, it is acceptable for high-temperature processing and provides steady output over application including polyethylene (PE), polypropylene (PP), polystyrene (PS), PVC, and engineering plastics.

The Role of Antioxidants in Polymer

• During manufacturing and processing, polymers are exposed to high heat, shear forces, and sometimes oxygen-rich environments. These conditions trigger oxidation, a chain reaction where free radicals attack polymer chains, causing discoloration, brittleness, and loss of mechanical strength.
• Antioxidant chemicals are added to disrupt this process and protect the material. There are two main categories:
• Primary antioxidants – Trap free radicals before they damage the polymer structure.
• Secondary antioxidants – Decompose hydroperoxides into non-reactive products, preventing further oxidation. Antioxidant 168 is a second-category stabilizer that works with primary antioxidants to provide sustained protection. It manages oxidation during high-temperature processing and in final usage, helping to preserve product quality, appearance, and durability.

How Antioxidant 168 Improves Thermal Stability

During polymer processing, high temperatures will initiate the production of hydroperoxides that increase chain scission and cross-linking reaction rates. Antioxidant 168 aims at this issue head-on through reaction with hydroperoxides before they degrade polymer chains. This not only halts subsequent oxidation but also inhibits physical strength and elasticity loss in the finished material.

Its hydrolytic stability ensures consistent performance even in moisture-rich environments, making it ideal for demanding applications such as extrusion, injection molding, and film production. Because it does not cause discoloration, it is particularly valuable in products where visual clarity or consistent color is important.

Together with primary antioxidants like Antioxidant 1010, it offers a combined action — instant and long-term protection against thermal and oxidative degradation. The overall result is higher processing efficiency, longer service life, and better overall material performance.

Applications Across Industries

The versatility of Antioxidant 168 makes it suitable for a wide range of industrial applications.

Plastics & Polymers

· Stabilizes compounds, such as PE, PP, PS, PVC, and masterbatches

· Protects against degradation, due to heat, during processing and use

Rubber Industry

· Retains elasticity and resiliency, even under severe operational conditions

Coatings & Paints

· Prevents oxidative degradation

· Prevents the degradation of the surface appearance and integrity over time

Lubricants & Oils

· Maintains thermal stability

· Prevents wear from oxidation to machinery parts

Adhesives & Sealants

· Enhances reliability for bonding

· Increases performance and durability over time

Other High-Temperature Applications

· Applicable to industrial materials requiring longevity and stability in extreme environments.

Best Practices for Using Antioxidant 168

Typically, for best performance of Antioxidant 168, it is included in processing or compounding for consistent mixing throughout the polymer. Amounts of Antioxidant 168 will vary with the polymer type and application but can often be used in the range of 0.05–0.5% by weight.

For best performance, Antioxidant 168 is frequently used with a primary antioxidant (such as Antioxidant 1010) to facilitate immediate and long-term protection. This synergistic antioxidant pairing will improve the material’s oxidation resistance and performance over time.

Proper storage of performance materials is important as materials should be kept in a cool dry space, free from sunlight and humidity. If you adhere to these guidelines, you will ensure the lacquer maintains thermal stability, performance reliability, and protects the physical properties and performance over cost differences in high temperature processing operations.

The Trusted Choice for Thermal Stability in Polymers

Antioxidant 168 is essential for thermal stability, mechanical properties, and a good appearance of many materials. The effective decomposition of hydroperoxides and the interruption of polymeric chains by Antioxidant 168 helps ensure that products retain good appearances and performance characteristics for a long time. Compared with other antioxidants, Antioxidant 168 is very stable to hydrolysis, does not discolour, and can be used with many types of polymers. As one of the largest producers of Antioxidant 168 (CAS No 31570-04-4), Vinati Organics sources high purity on purpose material and supplies it globally as Veenox® 168. As part of a quality-focused and compliance-driven organisation, you can trust Vinati Organics to be there and deliver the right chemistry for your application’s needs, while being certified for multiple countries, including FDA/Chemical and ACC compliance