The role of interphase in filler partition in rubber blends

The purpose of this study is to investigate the filler partition and the in terphase in rubber blends by means of dynamic-mechanical analysis. In order to determine the volume fraction and the thickness of the interfacial laye r in a preliminary stage unfilled blends with polymers of different degree of compatibility are investigated. The dynamic-mechanical analysis of blend morphology considers the dynamic loss moduli of the discrete phases in the glass transition regime. It allows for a description of the phase network connectivity and leads to a quantitative estimation procedure of the interp hase volume fraction and filler distribution between the phases. Since neig hboured phases with strong differences in mechanical response show high str ess gradients in their contact region, the effect of filling depends not on ly on filler loading and filler dispersion but also on the distribution coe fficient, i.e. the ratio of filler content of each polymer phase. It is qua ntitatively determined to what extend the filler is located in the interpha se and in the discrete polymer phases. The filler partition is shown to dep end on the thermodynamic interactions of the respective fillers and polymer s.