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A fractional calculus approach was used to study the correlation between the complex elastic modulus and the complex relative permittivity for a polystyrene (PS) film with thickness of ~80 μm. Experimental measurements were carried out using dynamic mechanical analysis and dynamic dielectric analysis. Experimental results show the mechanical and dielectric manifestations of the main relaxation (glass transition process), whose molecular mobility was analyzed by two innovative models: a mechanical fractional model and a dielectric fractional model. Parameters of fractional models show that, when temperature increases, the molecular mobility of the main relaxation also increases, but the cooperativity of mobility decreases. Besides, molecular mobility is greater in the mechanical manifestation of the main relaxation than in the electric manifestation. From theoretical results obtained from fractional models for the isochronal mechanic storage modulus, E′(T), and the isochronal relative permittivity, εr′T, a correlation model for mechanical and dielectric properties of PS film was obtained. This correlation model describes εr′T in function of E′(T). These results suggest that this correlation model can be used to study molecular mobility of mechanical and dielectric dynamic properties of the polymer films samples and predict changes in their behavior by modifying ambient conditions. [ABSTRACT FROM AUTHOR]