Multifunctional elastomeric composites with enhanced heat dissipation and thermal energy storage using nano-encapsulated phase change material and graphite fillers

Multifunctional elastomeric composites capable of simultaneously dissipating and storing heat are increasingly important for thermal regulation in compact systems. However, integrating thermally conductive fillers with phase change materials (PCMs) within flexible polymer matrix remains a challenge due to conflicting mechanical and thermal requirements. In this work, a hybrid natural rubber composite is developed by incorporating nano-encapsulated phase change material (nePCM) and graphite platelets in a natural rubber latex matrix through a scalable latex compounding and room-temperature vulcanisation process. The nePCM, synthesised via mini-emulsion polymerisation, shows a well-defined core–shell structure and high thermal stability while maintaining encapsulation integrity within the rubber matrix. Microstructural analyses confirm the uniform dispersion of both nePCM and graphite, without any agglomeration or leakage. The resulting composite exhibits a synergistic performance, enhancing thermal conductivity and latent heat storage while maintaining elastomeric flexibility. Differential scanning calorimetry shows a latent heat of 42 J g −1 within the selected phase-change temperature range, aligning with matrix dilution and filler incorporation. Mechanical tests reveal a trade-off between stiffness and stretchability associated with the incorporation of nePCM and graphite fillers. Transient thermal characterisation using thermocouples, infrared thermography, and Mach–Zehnder interferometry demonstrated enhanced heat spreading and thermal buffering performance. The developed composite exhibited a thermal conductivity of 0.81 W m −1 K −1 , a convective heat transfer coefficient of approximately 14 W m −2 K −1 , and a maximum heat flux of approximately 635 W m −2 . The combined effects of graphite and nePCM enabled simultaneous thermal conduction and energy storage within the NR matrix, demonstrating the potential of the composite as a flexible passive thermal-management material for compact electronic and energy-storage applications.