All polypropylene ( all- PP) composites were manufactured by exploiting the polymorphic forms of PP, in which alpha (alpha)- PP tapes worked as reinforcement and beta ( beta)- PP served as matrix. The mechanical performance of the composite was investigated in a range of frequencies and temperatures using dynamic mechanical thermal analysis ( DMTA). The volume fractions of matrix and reinforcement were estimated using optical microscope images. Both the DMTA and the static flexural bending tests revealed that the alpha- PP tapes act as an effective reinforcement for the beta- PP matrix. Time - temperature superposition ( TTS) was applied to estimate the stiffness of the composites as a function of frequency ( f = 10(-9)... 10(23)) in the form of a master curve. The Williams - Landel - Ferry ( WLF) model described properly change in the experimental shift factors used to create the storage modulus versus frequency master curve. The activation energies for the a and b relaxations were also calculated by using the Arrhenius equation.