NMR studies of multiple relaxations in polymers

Nuclear magnetic resonance (NMR) spectroscopy has become a valuable method of studying motions of chain segments and substituents in polymer molecules, since it views motion in away that, complements the information from other methods of measurement and since it extends the range of accessible frequencies to a region (∼108 cycles/sec.) that is beyond the usual range of dielectric and mechanical studies. In this report, a brief survey is given of the NMR relaxation processes and their significance to the understanding of thermal motions in solid polymers. The occurrence of multiple relaxation processes is discussed for a series of poly(n‐α‐olefins), poly(alkyl methacrylates), and some important elastomers, including natural rubber, polyisobutylene, and polybutadiene. Correlations are drawn with results in the literature on dynamic mechanical and dielectric relaxation in polymers.