Analysis of dispersion state of fillers in functionalized S-SBR/filler composites

Yamaguchi, Daisuke; Koizumi, Satoshi; Yuasa, Takeshi*; Sone, Takuo*; Tominaga, Tetsuo*

A comprehensive ultrasmall- and small-angle scattering analysis on the dispersion state of fillers in rubber/filler compounds is investigated. Recently, an effective size reduction of dispersible units of the fillers and consequential improvement of the property of the hysteresis loss was attained in the end functionalized S-SBR/filler system. Here S-SBR denotes solution polymerization styrene-butadiene rubber. To get more insight into the hierarchical structure of those systems, a complementary use of different contrasts between neutron and synchrotron X-ray was attempted. The different q-dependence of the scattering profiles taken by neutron and by X-ray suggested that two dominant structures exist in the system: one is the higher-order aggregations of the fillers and the other is the density fluctuations due to the vulcanization. By modification of the chain end of SBR with a functional group having the affinity for the fillers, the scattering signals originated from the vulcanization of SBR hardly changed, whereas those originated from the aggregation of the fillers distinctly changed. This tendency strongly supports the above scenario for the improvement of mechanical property of rubber/filler compounds.