Analysis of Filler Aggregation in Compounds Using Small-angle X-ray Scattering: Effect of Functional Group Introduced into Polymer-ends of Solution-polymerized SBR

Some modified styrene butadiene rubbers with functional groups at polymer chain ends have been prepared by solution polymerization system (S-SBRs). They showed reduction in the hysteresis loss of rubber compounds with silica or carbon black as reinforcing filler. Especially, the modified S-SBR with both primary amino group and alkoxysilyl group exhibited significantly lower hysteresis loss properties in both silica and carbon black compounds. In order to observe the dispersibility of silica in vulcanizates with this modified S-SBR directly, the measurements of transmission electron microscopy (TEM) and small angle X-ray scattering (SAXS) were carried out. The excellent dispersion state of silica in the vulcanizates with this modified SBR was observed. This modified SBR was also effective for improvement of dispersibility of carbon black in compound from the results of SAXS experiments. These results coincided with those obtained by dynamic viscoelastic measurement.