A method of analysis of the thermoviscoelastic properties of particulate composites with aggregating encapsulated inclusions is presented. Elastic and transport characteristics, expansion coefficients, loss tangents and creep factors are calculated based on the properties of constituents and composite microstructure. A parametric study is conducted to determine the effects of interface and microstructure on the variation of properties of the composite with filler stiffness. It is shown that aggregation increases realization of filler thermoviscoelastic characteristics in particulate. The presence of interlayer does not change qualitatively the variation of properties of non-aggregating particulate but modifies considerably the behavior of particulate with aggregating inclusions.