LETTERSstress components are present. The magnitude of the thermal stresses, however, is reduced by the presence of glassy subinclusion in the particle by a factor qsi inversely related to the volume fraction of subinclusion. Thus, for a given rubber content in the polyblend the level of thermal stresses decreases as more glassy polymer is transferred from the matrix into the dispersed phase.Although our analysis is based on a very simplified model of the composite particle, we believe that the main effects of the sub-inclusions on thermal stress distribution and magnitude have emerged.