Bio-based tin phytate interface assembled bismuth oxychloride for enhanced flame retardancy and smoke suppression in polyvinyl chloride coatings

The utilization of polyvinyl chloride (PVC) coatings is pervasive across numerous industries and market applications. However, due to its highly flammable nature, PVC coatings generate a large amount of toxic smoke when burning. We developed a bio-derived flame retardant and smoke suppressant, PASn@BiOCl, utilizing interface assembly technology. Compared to pure PVC coating, the addition of only 15 phr BiOCl@PASn significantly enhanced its various properties. The limiting oxygen index of PVC coating improved from 23.4% to 29.2%. Additionally, the UL-94 vertical burning test rating of the PVC coating has been improved from NR (No Rating) to V-0. More importantly, the peak heat release rate and peak smoke production rate of the PVC coating decreased by 70.7% and 60.7%, respectively, demonstrating the effective suppression of combustion and smoke generation. We also analyzed the pyrolysis products at different temperatures and the combustion behavior at various stages using Py-GC/MS and TG-IR techniques. It was observed that the char layer generated by PVC/BiOCl@PASn exhibited greater stability and density. The decomposition products including bismuth oxides, tin oxides, and phosphorus oxides formed a stable insulating layer on the charcoal surface, which effectively acted as a cohesive phase flame retardant. This highly efficient flame retardant and smoke suppressant PVC coating has enormous application potential in the fields of building materials, automobiles, textiles, and electrics.