Production of phase change materials from waste thermoplastics for thermal energy storage applications

The projected increase of over 3% in low-density polyethylene (LDPE) usage between 2024 and 2030 has raised concerns about plastic waste. This thesis addresses this issue by exploring eco-friendly energy storage solutions. A base phase change material (PCM) was produced from waste LDPE via pyrolysis, demonstrating the feasibility of "Plastic-to-Wax Conversion Technology." Composite PCMs (C-PCMs) were also developed by incorporating carbon nanotubes (CNTs) derived from waste materials. The base PCM was compared to commercial paraffin waxes using elemental analysis, FT-IR, GC-MS, TGA, DSC, and T-history techniques. Results showed that the waste-derived PCM could serve as a sustainable alternative for thermal energy storage. However, its low thermal conductivity required enhancement. For this purpose, CNTs were added at different ratios, and it was found that a 0.5 wt.% CNT addition significantly improved thermal performance. In the final stage, the base PCM was purified using DMA to remove impurities. Thermal analyses were then conducted to evaluate the melting/freezing points and latent heat capacity of the purified composite material. The combined effect of CNT addition and purification revealed improved thermal storage properties, offering a promising approach for addressing both plastic waste and energy storage challenges.