Valorization of Polymeric Municipal Solid Waste for Thermal Insulation Applications in Building Construction

Abstract

This research evaluates the feasibility of converting polymeric urban solid waste (USW) into thermal insulation materials for building applications by incorporating waste plastics into a rigid polyurethane (PU) matrix. Low-density polyethylene (LDPE) from municipal waste streams and high-density polyethylene (HDPE) from discarded lubricant and oil containers were processed as plastic particulates and integrated into PU to manufacture insulation panels. The materials were characterized using differential scanning calorimetry (DSC) and Fourier-transform infrared (FTIR) spectroscopy to assess thermal transitions and chemical composition. Panels were produced by molding without external heat or pressure, aiming to ensure uniform dispersion of the plastic fraction within the polymer matrix. The resulting composites were evaluated through key physical and thermal indicators, including apparent density, leachate production as an environmental impact indicator, and thermal conductivity as the primary measure of insulation efficiency. Granta EduPack software supported the selection and optimization of the polymeric matrix and hybrid composite configurations. Results comparing thermal conductivity and R-value at different mean temperatures indicate that LDPE additions can reduce thermal conductivity while maintaining structural integrity, likely supported by preservation of a porous matrix that enhances insulation performance. In contrast, high HDPE content tends to increase density and create heat-transfer pathways, raising thermal conductivity and reducing insulation effectiveness. Overall, the study highlights the technical potential of valorizing plastic waste in construction materials, supporting circular-economy strategies and reducing environmental impacts and carbon emissions by diverting plastics from incineration or landfilling.