PROTON NMR-STUDIES OF MOLECULAR-LEVEL MOBILITY IN VULCANIZED AND EPOXIDIZED 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 vulcanis ed samples. The data have been analysed by fitting procedures to give characteristic times which are discussed in terms of the mobility of t he various parts of the samples, and of their compositions (including the effects of paraffin wax and oil additives). Interpretation has bee n aided by recording free induction decays following a period of spin- locking. Carbon-13 magic-angle spinning spectra have also been measure d.