Used primarily as a high-performance antioxidant and stabilizer in polymers, especially in polycarbonates and engineering plastics. It protects materials from degradation caused by UV radiation and thermal oxidation, enhancing the durability and lifespan of plastic products exposed to harsh environmental conditions. Also employed in coatings and adhesives where long-term stability is critical. Its biphenyl structure provides strong radical scavenging ability, making it effective in preventing yellowing and loss of mechanical properties in transparent and high-clarity applications.