Interpretation of the dynamic mechanical response of heterogeneous polymer blends in terms of continuum models

Dynamic mechanical measurements have been widely used for characterization of polymer blends and composites. This paper discusses application of continuum models to interpretation of the dynamic mechanical response of isotropic microscopically heterogeneous polymer blends. The models typically predict shifts in apparent glass transition temperature (location of principal loss tangent maximum) for each blend constituent. Experimentally observed shifts in the apparent glass transition of heterogeneous blend constituents may thus arise at least partly for mechanical reasons rather than because of changes in the properties or glass transition temperature of the blend constituents. It is suggested that, for heterogeneous blends of well characterized phase morphology, changes in glass transition behavior of blend constituents be determined by comparison of measured and calculated loss tangent maxima. For two‐component blends, the loss tangent at the temperature at which the loss tangents of the blend constituents are equal may be useful as a further diagnostic tool for changes in loss mechanisius.