High-Value Upcycling of Waste Elastomers into Cushioning Airbag Layers for Work-at-Height Protective Clothing Airbag Layers for Work-at-Height Protective Clothing

Waste elastomer streams are difficult to convert into high-value products because crosslinked rubber phases, service-induced chain degradation, heterogeneous interfaces, and mixed additives reduce melt reprocessability and make secondary processing unstable. In this study, a waste-derived elastomer composite was developed as a flexible, sealable, and energy-absorbing airbag layer for work-at-height fall-protection clothing. Waste thermoplastic polyurethane/polyurethane elastomer scraps were used as the main recycled matrix, while ground waste rubber was introduced as a secondary modifier to improve cushioning performance and increase waste utilization. The recycled elastomers were sorted, cleaned, regenerated, compounded with compatibilizing and modifying agents, and processed into composite airbag-layer films. A virgin TPU film was used as the control, and formulations containing different recycled elastomer contents were evaluated in terms of morphology, thermal stability, processability, mechanical integrity, airtightness, burst resistance, impact cushioning, elastic recovery, cyclic compression stability, and ageing resistance. The results showed that moderate recycled elastomer incorporation improved energy dissipation while maintaining acceptable film continuity and sealing performance. Among the tested formulations, R30, containing approximately 30% recycled elastomer, provided the best balance between functional performance and resource recovery. Compared with virgin TPU, R30 retained suitable tensile strength, elongation, seam stability, and pressure retention, while reducing peak impact force and increasing absorbed energy. Higher recycled contents increased waste diversion but caused larger dispersed domains, higher void content, weaker heat-sealed interfaces, and reduced airtightness and durability. These findings demonstrate that waste elastomers can be upcycled into functional inflatable cushioning layers when recycled content and interfacial compatibility are properly controlled. The proposed strategy provides a potential high-value recycling pathway for flexible polymer waste in wearable protective equipment.