Surface flame retardancy of clay mineral powder infused onto the top of the layer of vinyl ester/bamboo composites through a modified VARTM process

The mechanical properties of fire-resistant biocomposites are significantly compromised owing to the high amounts of flame retardants (FRs) required for satisfactory results and the limited interfacial interactions between flame retardants (FRs) and polymer/natural fibers. The study addresses these challenges by modifying the vacuum-assisted resin transfer molding (VARTM) process to include two inlets and two outlets, allowing for the simultaneous infusion of an FR-filled resin on the top layer and pure resin in the remaining layers. Vermiculite clay mineral (VCM) was employed as an FR additive in vinyl ester (VE) using mechanical mixing methods such as the three-roll mill and overhead stirring. Bamboo fabric (BF) was used as the reinforcement in fabricating of VC-VE/BF fire-resistant bio-composites. Microscopic and spectral analyses confirmed clay dispersion and interactions within the composites. The FR-loaded side exhibited superior flame resistance (with a peak heat release rate (pHRR) of 467.1 W/g) and a 44% increase in thermal stability compared to the remainder of the composite. The findings indicate improved thermal and mechanical properties. The study presents a novel design for eco-friendly, FR composites.