Fabrication and characterization of graphene-loaded recycled poly(ethylene terephthalate) electrospun composite nanofibrous mats with improved thermal conductivity

In this study, graphene-loaded electrospun recycled poly(ethylene terephthalate) (rPET) nanofibrous mats were produced and characterized morphologically, spectrally, mechanically and thermally. Particularly, the effects of graphene nanoplatelets (GNP) and multilayer graphene (GML) in improving the thermal conductivity and heat dissipation abilities of rPET-based composite nanofibers were investigated. The morphological analyzes pointed out that 1% graphene loading led to smooth nanofibers while 5 and 10% of GNP-loading resulted in coarser nanofibers with rougher surfaces and agglomerations. The differential scanning calorimetry results pointed out that the crystallization temperature increased with increasing graphene content as a result of the pronounced nucleation effect. The thermogravimetric analysis demonstrated an improvement in the thermal stability of the composite nanofibers. The thermal conductivity coefficients increased to 25.422 W/mK-35.842 W/mK for rPET/GNP nanofibers and up to 62.669 W/mK for rPET/GML nanofibers, compared to that of 12.753 W/mK for neat rPET nanofibers which correspond to an increase between 99 and 391%. Heat dissipation capability of the graphene-loaded composite nanofibers was illustrated with infrared thermography data, displaying an increase in the average surface temperature of the nanofibrous mats between 2 and 19°C at 30 s of heating. The results suggest the use of the graphene-loaded rPET composite nanofibers as textile materials for thermoregulating applications. Highlights: Recycled poly(ethylene terephthalate)/graphene composite nanofibers are electrospun. Thermal conductivity of graphene-loaded nanofibers increases by up to 391%. Graphene loading in nanofibers leads to faster and more uniform heat dissipation. Mechanical properties of composite nanofibers improve. Value-added recycled polyester materials for thermal management are foreseen.