Abstract
Bulk and photo initiated polymerization of styrene at 60° have been investigated in the presence of diradical‐producing initiators. Cyclic peroxides such as cyclohexanone peroxide, ascaridole, ergosterol peroxide, dimeric benzaldehyde peroxide, and cyclohexene were used as polymerization initiators. It is concluded that the propagation reactions proceed via monoradicals for these photoinitiated reactions.