Effect of Graphene Diameter on Heat Transfer Pathways in Graphene/PVDF Nanocomposite Membranes

Abstract

Modification of polymers by using high thermal conductivity fillers has become a common strategy for enhancing thermal conductivity. The low thermal conductivity of poly-(vinylidene fluoride) (PVDF) limits its development and application in the field of heat dissipation. The distinctive phonon mode exhibited by reduced graphene oxide (RGO) demonstrates exceptional thermal conductivity. In this study, PVDF served as the matrix, and composite membranes were prepared by incorporating nanothermal conductive material (graphene). The objective of enhancing the thermal conductivity has been achieved. Experimental outcomes were derived through characterization. RGO sheets smaller than 10 μm were observed to maintain the external surface morphology of the membrane unchanged. The porosity exhibited a gradual increase with growing lamellar diameters. The membrane's thermal conductivity demonstrated an initial rise followed by a subsequent decline. The peak value reached 0.15 W/m K when the RGO size ranged from 1 to 3 μm. However, further enlargement of the graphene size resulted in a significant decrease in the thermal conductivity. The presence of large pores, induced by larger-size RGOs in PVDF, had a pronounced adverse impact on the membrane's thermal conductivity. The size, surface microstructure, dosage, and composite morphology of thermally conductive particles play a pivotal role in influencing mechanical, electrical, thermal, viscosity, structural control, and processability aspects. Thus, comprehending the morphology of thermally conductive particles holds significance in the exploration, formulation, and advancement of thermally conductive polymer materials.