Novel Ethylene-Propylene-Diene Monomer rubber panels filled with Phase Change Material and expanded graphite for energy efficiency of buildings

The integration of organic Phase Change Materials (PCMs) in building walls has become essential to surpassing the limitations of conventional insulation. Within this scope, we developed novel Ethylene-Propylene-Diene Monomer (EPDM) composite materials incorporating paraffin as PCM. To achieve this, Expanded Graphite (EG) was introduced via a preliminary vacuum impregnation process. This carbonaceous filler acts as a multifunctional support, ensuring shape stability and enhancing the structural integrity of the rubber matrix. The resulting composites exhibit an outstanding melting enthalpy of 167 J/g—a record-high value for EPDM-based systems within the 22–31 °C range—while the percolative EG network raises thermal conductivity to 1.7 W/m·K (a ten-fold increase over the neat PCM). Dynamic thermal tests in a climatic chamber confirmed a significant thermal lag and the ability to dampen temperature peaks effectively. Furthermore, mechanical characterization at 21 °C and 40 °C demonstrated that the panels maintain a compressive strength exceeding 0.1 MPa even when the PCM is molten, ensuring structural reliability during storage and transport. In summary, leveraging a superior synergy between heat storage and thermal transport validated by Figure of Merit (FoM) analysis, these novel PCM/EG-based panels offer a high-performance solution for passive cooling applications in sustainable architecture.