Nuclear magnetic resonance study of rubber–carbon black interactions

The mobilities of polymer chain segments in mixtures of rubber and carbon black were investigated by nuclear magnetic resonance. Spin–spin relaxation time (T₂) measurements on cis-polybutadiene and ethylene–propylene–diene rubber (EPDM) bound rubbers detected at least two relaxing regions: an immobile region and a relatively free region. The molecular motions in the relatively free region are still constrained compared to those of the pure gum.