Network density and diene conversion in peroxide-cured gumstock EPDM rubbers : a solid-state NMR study

Peroxide-cross-linked EPM and EPDM rubbers have been investigated with magic-angle spinning 1H NMR spectroscopy and static 1H NMR relaxometry. The results yield a consistent nanoscale picture of the chemical and physical network properties in terms of chemical cross-links formed via macro-radical combination, chemical cross-links formed via addition to the double bonds, and physical cross-links resulting from chain entanglements.