Ovalioglu, H., The Effect of Sample Age and Neutron Radiation to Dynamic Nuclear Polarization Parameters in Some Asphaltene Suspensions. Journal of Dispersion Science and Technology, 2011. 32(10): p. 1470-1476.
Nuclear magnetic resonance and the Overhauser effect type dynamic nuclear polarization experiments were performed to study suspensions of asphaltene in the xylene isomers at a low magnetic field of 1.44mT at room temperature. Intermolecular spin-spin interactions occur between nuclear spins of hydrogen in the solvent medium and the free electron spins in the asphaltene micelles. The samples were prepared in three different asphaltene concentrations at vacuum. The samples were waited for four years and dynamic nuclear polarization parameters were found via dynamic nuclear polarization experiments performed again. Thus, it was investigated the effect of sample age to dynamic nuclear polarization parameters. In addition, the medium concentrations of each sample were exposed to radiation for 48 hours and neutron radiation effects to the dynamic nuclear polarization parameters were investigated. The results are discussed.