Phase-Change Heat Capacity Characterization of Paraffin Wax–Silicone Rubber Microcapsules: A Flexible and Surface-Adaptive System for Thermal Management in Electronic Devices

Phase-change materials (PCMs) with crystalline structures and high latent heat of fusion have gained significant attention for thermal management and energy storage applications. In this study, PCM microcapsules were synthesized via interfacial polymerization combined with a solvent–nonsolvent technique, using paraffin wax with the melting point of 46–48 °C, as the core material and a room-temperature vulcanized silicone rubber as the shell. The microcapsules were embedded into flexible high-temperature-vulcanizing silicone rubber to fabricate a surface-adaptable thermal regulation system. Characterization using Fourier-transform infrared spectroscopy, attenuated total reflection, and field emission scanning electron microscopy confirmed successful paraffin wax microencapsulation, with a dominant particle size around 2 µm. Thermal performance evaluations showed that incorporating 30 wt.% paraffin wax microcapsules enhanced thermal stability and achieved an energy absorption efficiency of approximately 50% in a single thermal cycle. Kinetic analysis of the melting and crystallization processes revealed key characteristics of the phase transition behavior in the encapsulated state. The system also exhibited a specific heat capacity of up to 6500 J·kg⁻¹·K⁻¹ during melting. When applied to an electronic circuit board, the fabricated PCM system delayed the temperature increment by more than 75% compared to the control, demonstrating strong potential for electronic thermal management.