Mechanism of Peroxide Cross-Linking of EPDM Rubber

The results of three experimental studies, i.e. GC-MS of peroxide-crosslinked alkene/alkane mixtures, 13 C NMR of peroxide-cured, 13 C-labeled 2 -ethylidene- 5 norbornene - ethylene-propylene-diene-monomer (EPDM) and EPR of peroxide curing of EPDM, are combined, yielding a more accurate description of the mechanism of peroxide cure of EPDM. Both alkyl and allyl macro-radicals are formed via H-abstraction from the EPM main chain and the residual diene unsaturation, respectively. Combination of these macro-radicals yields alkyl/alkyl, alkyl/allyl and allyl/allyl cross-links and addition of these macro-radicals to the residual diene unsaturation yields alkyl/alkene and allyl/alkene cross-links.