ABSTRACT
Polypropylene (PP) needs protection in every stage of its life cycle. It starts with storage, immediately after manufacturing. Then, a small amount of a phenolic antioxidant usually gives sufficient protection. It continues with processing, during which an adequate stabilization is a prerequisite for minimizing degradation of PP in the molten state at temperatures between 200° and 300°C." It ends with a suitable stabilization for the application foreseen. This is a stabilization against thermal oxidation only, if PP is not to be exposed to light. It will be a stabilization against photothermal oxidation if ultraviolet (UV) light exposure is involved. The requirements for polyethylene (PE) are similar to those for PP, but the stabilizer levels are usually lower because PE is inherently less sensitive to oxidative attack than PP.
