Characterisation of crosslinked elastomeric materials by 1H NMR relaxation time distributions

One of the most critical structural parameters in elastomeric materials is the density of cross-linking between the polymeric chains. This chemical feature greatly affects chain motions and is determinant in controlling mechanical properties of the final product. NMR techniques are widely and efficiently applied to investigation of such materials. In this study we have measured both transverse and longitudinal 1H relaxation times of a series of polybutadiene rubber samples with increasing crosslink density induced by chemical treatment. This approach allowed the observation of T1 and T2 decrease with the increase of crosslink density in the samples examined. The data obtained have been analyzed and compared to theoretical models.