Recycled Polyvinyl Chloride/Highly Filled Modified Desulfurization Ash Composites With Enhanced Mechanical Properties, Flame Retardancy, and Smoke Suppression

Alternative filler for calcium carbonate used to fill recycled polyvinyl chloride (r‐PVC) is an urgent need due to the destruction of the ecological environment and the poor performance of r‐PVC products. Herein, the use of circulating fluidized bed flue gas desulfurization ash (CFB‐FGDA), a by‐product from the steel industry with fine particle size and excellent stability, was fully explored. Stearic acid (SA) and polyethylene wax (PEW) were used to modify the dry desulfurization ash, and the effects of coating sequence on surface coating, system processing performance, and material mechanical properties were studied. The results show that the coating sequence is the SA → PEW system, and its surface coating effect, processing fluidity, and mechanical properties are better than the coating sequence in the PEW → SA system. A high‐filling composite was fabricated by incorporating modified CFB‐FGDA (50 wt%) into r‐PVC, enhancing flame retardancy, smoke suppression capabilities, and mechanical performance compared with traditional calcium carbonate‐filled stone plastic flooring. Fire safety tests showed significant improvements: ignition delay increased from 259 to 404 s, total smoke release decreased from 9.0 to 7.8 m2, and total heat release dropped from 18.0 to 9.7 MJ/m2 when comparing r‐PVC/calcium carbonate to r‐PVC/CFB‐FGDA samples. Furthermore, it was also found that superior static bending strength, reduced warping under thermal changes, and improved dimensional stability were achieved in the r‐PVC/CFB‐FGDA composites compared with traditional r‐PVC/calcium carbonate products. These enhancements suggest that the r‐PVC/CFB‐FGDA composite is a promising alternative material for construction applications.