Inhibitors
Inhibitors are chemical substances capable of inhibiting or killing the chain growth by combining with the active free radicals and forming either stable products or inactive free radicals. Hydroquinone, nitrobenzene, dinitrobenzene and benzothiazine are some of the inhibitors used in the polymer industry.
Atmospheric oxygen is a good inhibitor. The inhibiting action of oxygen is due to its biradical nature, as depicted in the following figure. This is why radical polymerization is generally carried out under nitrogen atmosphere. A major use of inhibitors is during production and storage.
Applications of Free Radical Polymerization: