Proton NMR studies of molecular-level mobility in vulcanised and epoxidised natural rubber

Proton spin-lattice relaxations in the laboratory and rotating frames, together with transverse relaxation (free induction decay), have been measured for natural and epoxidised rubber, plus a series of vulcanised samples. The data have been analysed by fitting procedures to give characteristic times which are discussed in terms of the mobility of the various parts of the samples, and of their compositions (including the effects of paraffin wax and oil additives). Interpretation has been aided by recording free induction decays following a period of spin-locking. Carbon-13 magic-angle spinning spectra have also been measured.