THE EFFECT OF CARBON-BLACK FILLING AND CROSS-LINKING IN STRETCHED SBR NETWORKS - A H-2-NMR STUDY

The line splitting delta-v in H-2-NMR spectra of deuterated benzene in stretched crosslinked SBR depended linearly on the classical stretch term alpha-2-1/alpha for samples with and without carbon black filling. The ratio LS = delta-v/(alpha-2-1/alpha) was measured in dependence on the solvent fraction PHI. The extrapolated value L of this ratio at PHI = 0 gave a linear dependence on the inverse molecular mass 1/M(c) of inter-crosslink chains. This was expected according to a simple model of chain dynamics and offers a further NMR-method for M(c)-determination even in filled networks. However, the slope of the L(1/M(c))-line increases with an addition of carbon black which indicates a higher molecular order. Three reasons for this could be discussed. However, one of them is preferable.