The selection and use of free radical initiators

There are over 50 different organic peroxides and azo compounds (in over 100 different formulations) produced commercially as free radical initiators (curing agents) for the polymer and resin industries. Thus, the user has many initiators to choose from and has usually relied on the resin and/or initiator producer to select his initiator system. This paper will discuss these initiators in general showing the different types‐ of initiator classes; how and why the activity of each class of initiator is varied by structure changes; how different initiators and/or promoter levels affect the curing process; and present guidelines that an end user might use to choose the right initiator for his resin system.