Analyses of hierarchical structures in vulcanized SBR rubber by using contrast variation USANS and SANS

The hierarchical structures of poly(styrene-ran-butadiene) (SBR) rubbers vulcanized with sulfur in swollen state were investigated by using ultra small angle neutron scattering (USANS) and small angle neutron scattering (SANS) technique. The scattering intensity can be described by the equation consisting of two Debye-Bueche equations and Ornstein-Zernike-Debye equation indicating that the inhomogeneous structure with the size of 500 to 900 Å exits, in addition to the inhomogeneous structures with the size of 70 to 100 Å with the networks. As the results of the analyses of contrast variation USANS and SANS, The origin of the inhomogeneous structures with the size of 500 to 900 Å was found to consist of ZnO added as activator of sulfur vulcanization, and we was able to yield the size of ZnO being in the order of 1000 Å quantitatively from the partial structure factor of ZnO.