1. Free-Radical Formation
The decomposition of initiators is induced by heat in the case of molding compounds or by accelerators at temperatures below the decomposition temperature of the initiator in the case of cast polyester resins. Two types of accelerators are used, metal salts—mainly cobalt salts—and amines. The oxidoreduction of metal salts by peroxides produces free radicals. The process is very efficient since both lower and higher valencies of cations participate in the reaction.
R02H + C02+ —————— ► C03+ + RO + 0H“
ro2h + C03+ —————— ► C02+ + ro2 + H4-
C03+ + 0H~ ————— ► C02+ + OH