Thermal Diffusivity and Thermal Effusivity Enhancement of Graphene based Polyvinyl Chloride Nanocomposites

The development of thermal diffusivity, thermal effusivity and heat capacity per unit volume of polymer nanocomposites, based on PVC filled with different concentration of graphene flakes up to 1.3 vol.% have been investigated using photoacoustic technique. The composites were prepared in the form of thin films with relatively small thickness (23–30 μm). Morphological and structural characterizations of the prepared composite films have been performed using laser confocal microscope, SEM and Raman spectroscopy. The composites exhibit an improvement in both thermal diffusivity (175%) and thermal effusivity (136%) of their values for neat polymer at the highest graphene content used. However, with increasing graphene content no significant variations in the measured values of heat capacity were obtained. The experimental results were analyzed using the mixed model for the thermal conductivity of a two-phase system. We obtained good agreement between our results and the predictions of this model at thermal diffusivity (= (1.5 ± 0.07) × 10⁻⁴ m²s⁻¹) and thermal effusivity (= (1.83 ± 0.06) × 10⁴ Ws^1/2m⁻²K⁻¹) of fillers. The predicted thermal diffusivity value of graphene flakes is comparable to the published thermal diffusivity of graphene plates. On the other hand, according to the author's knowledge, the thermal effusivity of graphene was not previously studied. However, the thermal effusivity predicted in this work is in fair agreement with that estimated using the reported thermal properties data of graphene.