The origin of a new transition in dynamic mechanical spectra of multilayer polymeric composite

An additional damping transition at −25 °C, which has never been reported in blended system, is observed in dynamic mechanical spectra (DMS) of isotactic polypropylene/ethylene 1-octene copolymer (iPP/POE) composites with alternating multilayered structure. With increasing layer number, this additional transition becomes larger followed by the decrease of the damping peak of iPP. Through mechanical analysis, the maximum of interfacial stress is found at −25 °C, where the new damping peak appears coincidentally. Hence, the origin of the additional transition is ascribed to the advanced defreezing of chain segments of iPP for balancing difference of the mechanical response between adjacent layers.