A series of rubbers has been investigated in the 1-100 kHz range by proton relaxometry (measurement of the nuclear relaxation rate as a function of the amplitude of the magnetic field along which nuclear magnetization is aligned: the static field B-0 for the longitudinal rate R-1, the radio-frequency field B-t for the rotating-frame rate R1,). Data can be interpreted according to R-i = a(i) + bi/v(xi), where v(0.1) = gammaB(0,1)/2pi (gamma being the gyromagnetic ratio), the index i charactetizing the sample as well as the nature of the relaxation parameter (longitudinal or rotating-frame). a(i) and b(i) are related to residual dipolar couplings and thus afford the possibility of material discrimination. (C) 2003 Published by Elsevier Science B.V.