NMR measurements of gaseous sulfur hexafluoride (SF6) to probe the cross-linking of EPDM rubber

The effects of embedding gaseous SF6 into EPDM rubber were investigated using NMR methods. It was found that observed sorption and desorption processes follow the behavior of the dual mode sorption model. A strong correlation was found between EPDM cross-linking and transversal relaxation time of embedded SF6. EPDM samples with different cross-link densities, preliminarily determined by H-1 transversal relaxation using the Gotlib model and Litvinov's method, were investigated using embedded SF6. The sensitivity of the F-19 transversal relaxation rate of SF6 to the EPDM cross-link density variation was found to be at least 10 times higher than for H-1 in the polymer chain. First experiments on probing the swelling effects in EPDM due to its contact with polar liquids have been performed. Copyright (c) 2005 John Wiley & Sons, Ltd.