STRUCTURE ANALYSES OF SWOLLEN RUBBER–CARBON BLACK SYSTEMS BY USING CONTRAST VARIATION SMALL-ANGLE NEUTRON SCATTERING

In a previous study [Takenaka et al., Macromolecules 42, 308 (2009)], we have investigated the polymer layers absorbed on silica (Si) particles in rubber–Si systems with the contrast variation small-angle neutron scattering (SANS) method. We have investigated the polymer layers absorbed on carbon black (CB) particles in rubber–CB systems with contrast variation SANS method. The scattering intensities of specimens swollen by the solvents having various scattering length densities were measured. The contrast variation SANS for the specimens yielded partial scattering functions: the scattering function for polymer–polymer correlation SPP(q), the scattering function for CB–CB correlation SCC(q), and the scattering function for polymer–CB correlation SPC(q). The analyses of SCC(q) explored the structures of the aggregates formed by CB particles. The analyses of SPC(q) and SCC(q) clarified the existence of dense polymer layers around CB aggregates. Several characteristic parameters are estimated from the analyses, such as the size of aggregates, the thickness of layers, and the volume fractions of polymer layers and matrix. We found that the adsorption layer around CB aggregates is thicker than that around Si aggregates in rubber–Si systems.