Graphite and metal nitrate-infused HDPE composites for enhanced thermal performance in energy-efficient building envelopes

Abstract The growing market of efficient thermal management materials in architectural and energy systems has led to the creation of polymer composite materials with better heat dissipation properties. In this work, the high-density polyethylene (HDPE) composites loaded with graphite and different metal (Cu, Mg, Bi, Fe, Sr, Na) nitrate doped carbon quantum dots (CQDs) are presented. The metal nitrate doped CQD is synthesized using pulsed thermal treatment using citric acid, urea, and metal nitrates. The Cu-doped CQD composite exhibited a substantial enhancement in thermal conductivity compared to bare HDPE, with an improvement of approximately 10.5%. Additionally, dielectric measurements revealed that Bi-, Fe-, and Cu-doped composites exhibited the highest improvements in conductivity, indicating strong interfacial interactions and effective charge transport pathways within the composite matrix. Analysis such as Fourier Transform Infrared Spectroscopy (FTIR), X-ray Diffraction (XRD), Differential Scanning Calorimetry (DSC), Thermogravimetric Analysis (TGA), Scanning Electron Microscopy (SEM), and dielectric spectroscopy analyses further revealed extensive interaction between filler matrices, a decrease in phonon scattering, and a positive increase in crystallinity which led to the improved thermal performance.The TGA results showed that the composite exhibited greater thermal stability, and the residue mass after the decomposition process was 9%, indicating increased carbonization and structural integrity. These results point to a scalable approach for developing lightweight corrosion resistant thermal management composites that can be used in the design of energy efficient wall panels and heat-dissipative building materials.