Abstract
All polyolefin-based plastics materials undergo oxidation reactions, which can occur at every stage in the life cycle of a polymer during manufacture and storage, as well as in processing and end use. Antioxidant systems protect polymers against oxidation by controlling the molecular weight changes that lead to a loss of physical, mechanical and optical properties. Traditional stabilizer systems for polyolefins are typically based on a combination of a phenolic antioxidant and a phosphorus based melt processing stabilizer. The phenolic antioxidant provides melt processing stability as a hydrogen atom donor and free radical scavenger, but is also incorporated to achieve some desired level ofthermal stability. The phosphorus-based melt processing stabilizer functions as a hydroperoxide decomposer during the melt compounding step.
Recently, Ciba introduced a powerful new melt processing stabilizer based on lactone chemistry. The addition of this new chemistry to the traditional binary systems boosts the stabilization performance, while having a positive impact on the performancecost profile of the system. The benefits of the lactone chemistry are also seen when it is combined with high performance phosphorus-based processing stabilizers, and when it is used with phenolic antioxidants for specific end use applications. This paper presents performance data for traditional binary antioxidant systems, high performance phosphorus based systems, and phenolic antioxidants, when they are combined with the lactone. The paper also describes the performance of new polyol systems based on lactone technology. The data demonstrates the opportunity for an improvement in the performance cost profile of these systems when combined with lactone chemistry.