Antioxidants: Polymers such as polypropylene (PP) are not usable outdoors without appropriate stabilizers, because of the presence of readily removable hydrogen atoms on the tertiary carbon atoms.

• 抗氧剂：有的聚合物,如聚丙烯,如果其中不加适当的稳定剂,就不能在户外使用,这是因为它分子中的碳原子上存在着易消除的氢原子。