A facile bioinspired fire coating hybridising carbon-derived peanut shells and black phosphorous for timber structures : experimental and numerical characterisation

Abstract

In recent years, the utilisation of bio-based materials in flame retardants (FRs) has been widely advocated due to significant recyclability, flame retardancy and cost-effectiveness. For example, carbon derived from peanut shells (CPS) with sheet-like structures are natural FRs with rich carbon sources for epoxy resins (EP). In this study, we hybridised CPS with black phosphorous (BP) via the ball milling method and embedded it in EP to exploit their synergistic effects. CPS enhances the formation of a durable char layer, complemented by BP's dual action in scavenging radicals in the gas phase and promoting char formation in the condensed phase. The modified EP (EP/BP/CPS) has offered excellent flame resistance towards pinewood that 3 wt% addition of EP/BP/CPS can significantly reduce the peak heat release rate (pHRR) and total heat release (THR) and total smoke reduction (TSR) by 45 %, 14 %, and 28 % compared to pure EP coated pinewood. Importantly, we proposed a numerical framework that can be fully utilised to integrate the fire field model, reconstruct the fire scene and predict the fire development stages by coupling pyrolysis kinetics with computational fluid dynamics (CFD). The combustion behaviour of pinewood coated with EP/BP/CPS was characterised. In particular, the burning characteristics such as pHRR, time to ignite (TTI) and burning duration were well-predicted. This work has proven that the hybridised EP/BP/CPS is an effective and sustainable FR coating for timber structure buildings, while its combustion behaviour can be numerically characterised for large-scale fire safety assessment.