Fabrication of bio-based modified flame retardant for enhancing the flame retardancy, smoke suppression, UV aging resistance and antibacterial performance of polypropylene/corn straws composites used in building fire protection

Halogen-containing flame retardants produce a large amount of toxic smoke during combustion, which jeopardizes the environment and human health. Thus, P/N-containing halogen-free flame retardants have attracted widespread attention. In this work, a novel halogen-free intumescent flame retardant material (APP@Arg-Cu) was prepared using arginine (Arg) and copper ions (Cu²⁺), followed by ammonium polyphosphate modification. This flame retardant was applied to a wood-plastic composite (WPC), and its flame retardancy, smoke suppression, antibacterial, and UV aging resistance properties were evaluated. The addition of APP@Arg-Cu significantly improved the limiting oxygen index (LOI) of WPC, with the LOI value rising from 21.1 % to 30.2 %. Consequently, the UL-94 V-0 rating was easily achieved. Moreover, peak heat release (PHRR), total heat release (THR), and total smoke production (TSP) were reduced by 55.7 %, 21.4 %, and 63.5 %, respectively. The introduction of Arg-Cu also enhanced the graphitization of the residual carbon, optimized its structure, and improved its thermal stability. An antimicrobial test showed that WPC/APP@Arg-Cu had a significant inhibitory effect on Escherichia coli and Staphylococcus aureus. After UV aging treatment for up to 600 h, the mechanical properties of WPC, WPC/APP, and WPC/APP@Arg-Cu were reduced by 18.5 %, 37.2 %, and 8.9 %, respectively, indicating the better UV aging resistance of WPC/APP@Arg-Cu. Moreover, while a house model constructed entirely of WPC collapsed within 60 s of exposure to a butane flame, a house model made using flame-retardant WPC remained intact after burning for over 1000 s. This study proposes a green and low-cost flame retardant that enables the wider application of high-performance WPC. • Preparing bio-based flame retardant from corn stover helps reduce resource waste. • Biodegradable retardant reduces chemical retardant-based environmental pollution. • This flame retardant effectively reduces smoke and toxic gas generation. • Treated wood-plastic composites show good flame-retardant properties. • Treated wood-plastic composites show antibacterial properties.