Hybrid Microencapsulated Phase-Change Filler/Polymer Composites With Low Heat Buildup for Sustainable Applications

Excessive heat buildup in rolling tires accelerates rubber degradation and increases energy consumption, yet strategies for active thermal management in tire-grade natural rubber (NR) remain limited. Phase-change materials (PCM) offer latent heat storage for temperature regulation, but their incorporation into NR without sacrificing mechanical performance is challenging. Here, we design hybrid microencapsulated PCM/NR composites by introducing silica-shelled paraffin microencapsulated PCMs (MEPCM), prepared via a sol–gel route, as co-fillers with reinforcing silica. Partial replacement of silica with MEPCM endows the NR matrix with heat-absorption and energy-storage capability while maintaining a viable balance of stiffness, strength, and abrasion resistance. Under rolling and compression tests, composites containing 20 phr MEPCM exhibit 26.5% and 28.5% reductions in rolling and compressive heat generation, respectively, relative to the silica-filled control. Although high microcapsule loadings compromise mechanical strength and durability, moderate MEPCM incorporation preserves tensile and wear properties within ranges suitable for tire applications. Interfacial reinforcement via the silane coupling agent Si-69 enhances filler–rubber interactions, leading to improved tensile strength, elongation at break, and abrasion resistance. These results establish hybrid MEPCM-filled NR as an effective strategy for developing low-heat-buildup, temperature-regulating rubbers, offering a promising platform for next-generation green tire materials.