Azo and Peroxy Initiators

The most common form of initiator for radical polymerization is a compound which acts as a thermal source of radicals. Typically this is an azo or peroxy initiator. A particular initiator will have a convenient decomposition rate over a relatively narrow temperature range. Accordingly an initiator is often categorized according to its half-life at a given temperature and many such tabulations can be found (see, for example, ref. 1). The initiators may also be used at lower temperatures when they form one component of a photochemical or redox initiation system.