Recent advances in aramid-based multilayer composites for thermal-moisture comfort regulation in firefighter protective clothing

Firefighters operating in high-temperature and high-intensity environments are vulnerable to heat stress caused by metabolic heat, sweat accumulation, and deterioration of the clothing microclimate. Aramid fibres are widely used in firefighting suits because of their excellent flame resistance, thermal stability, and mechanical strength; however, their hydrophobicity and low moisture regain restrict liquid sweat transport and water vapour release. This review examines the structural evolution of aramid-based firefighting materials and critically summarises single-component, binary, and multi-component composite systems. It analyses how moisture-wicking fibres, breathable membranes, phase-change materials, air-spacer structures, and aerogels regulate liquid water transport, vapour diffusion, latent heat buffering, and sensible heat insulation, while comparing key indicators including TPP, Rct, and Ret. Existing studies show that these strategies regulate heat and moisture transfer through different mechanisms, but their overall performance depends on interfacial compatibility, pore continuity, structural configuration, and service ageing. Future research should emphasise dynamic heat–moisture testing, full-garment and human-subject evaluation, and performance retention after thermal, hydrothermal, mechanical, and laundering ageing. This paper identifies material- and interface-level design considerations for improving heat and moisture management while preserving thermal protection.