Abstract
Fire sensors offer an effective strategy for mitigating fire hazards. This work reports the development of self-sensing glass fibre–reinforced composites (GFRCs) by incorporating a graphene oxide (GO)–aramid sensing layer into their structure. Two sensor configurations were explored: GO–coated aramid webs (GO–AW) and GO–aramid nanofibre films (GO–ANF). These sensors function via the thermal reduction of GO to conductive reduced graphene oxide (rGO) under heat or flame, enabling rapid (<1 s) fire detection and real-time wireless alerts via an IoT–enabled system. The GO–AW web strip, patterned with conductive ink electrodes and embedded in a GFRC laminate, effectively responded to both conductive (direct contact) and radiative (external heat flux) heat, acting as a robust pre–fire sensing material. Integration with an ESP32 microcontroller enabled wireless, real–time monitoring and instant alerts, ensuring practical applicability in fire–safety–critical environments. Furthermore, the incorporation of GO–AW enhanced the thermal and mechanical properties of the composite, with the flexural modulus increasing from 3.1 to 6.5 GPa and the glass transition temperature from 86 °C to 94 °C. The presence of GO–AW in the GFRC also reduced flammability of the composite, indicated by reduction in the peak and total heat release rate by 22 and 45 %, respectively in cone calorimetric experiments. Overall, the integration of GO–AW not only imparted fire-sensing functionality but also improved the composite's structural integrity and flame retardancy, demonstrating broad potential for structural and industrial applications.