Biodegradable graphite-reinforced composites for energy efficiency and renewable energy storage applications

The demand for sustainable solutions in energy efficiency and renewable energy systems continues to grow as environmental and climate concerns intensify. Materials that can support low-carbon technologies and improve thermal management are essential for advancing clean energy and smart infrastructure. Traditional phase change materials, while effective in heat storage, are often limited by their environmental toxicity, lack of biodegradability, and poor long-term stability. This study focuses on developing biodegradable polymer-based composites with enhanced thermal properties using expanded graphite to address these limitations and support the transition to sustainable materials in energy systems. The composites were formulated using blends of polycaprolactone (PCL), polyhydroxybutyrate (PHB), and polyethylene oxide (PEO), with expanded graphite added to improve thermal conductivity and shape stability. Characterization was conducted using differential scanning calorimetry (DSC), thermogravimetric analysis (TGA), scanning electron microscopy (SEM), Fourier-transform infrared spectroscopy (FTIR), and X-ray diffraction (XRD). Among the tested formulations, the PCLB/PEO/EG composite achieved a melting point of 58.01°C and enthalpy of fusion of 70.44 J/g, while maintaining thermal stability and mechanical integrity after extensive thermal cycling. A minimum of 15 % expanded graphite was found essential to ensure structural durability. These materials present a good solution for heat storage in solar thermal applications and for thermal regulation in compact electronic devices. Their biodegradable nature and strong thermal performance contribute directly to the goals of energy efficiency, renewable energy adoption, and sustainable consumption. Future research may explore scaling up production and assessing integration into real-world smart energy systems.