Abstract <p>The mechanisms of charge accumulation and relaxation in the initial and composite films based on polypropylene filled with montmorillonite and high-density polyethylene filled with diatomite were investigated using thermally stimulated spectroscopy methods. It was shown that the introduction of filler into the polymer matrix leads to a change in the polarization mechanism due to the formation of new deep traps at the polymer/filler interface, along with a simultaneous reduction in the conductivity of the materials due to the hydrophilic properties of the fillers. Numerical estimates of the parameters of electrically active defects (activation energy and frequency factor), as well as the relaxation time of the electret state in the studied samples, are provided. The possibility of using the studied composite materials as active packaging for food products is considered.</p>