Effect of modified steel slag on properties of rigid polyurethane foam

Abstract The resource utilization of steel slag (SS) represents a critical strategy for integrating environmental protection with sustainable industrial development. In this study, SS was employed as an inorganic filler to investigate the effects of SS particle size and proportion on rigid polyurethane foam (RPUF). Optimal RPUF/SS composites were achieved with an 800-mesh particle size and a 50 % addition ratio. Additionally, the impact of modified SS on the performance of RPUF was examined. The findings indicated a 17.2 % enhancement in thermal insulation properties and a substantial improvement in flame retardancy, evidenced by a 5.7-fold increase in char yield. Despite a reduction in compressive strength, the practical applicability of the composites was not compromised. The performance of the composites was found to be independent of the specific surface area of SS but was significantly influenced by the type of modifier employed (phosphoric acid, formic acid, and silane coupling agents KH550, KH560, KH570). The modification of SS with appropriate agents is essential for enhancing the performance of RPUF/SS composites and for realizing high-value resource utilization of SS in the polyurethane industry.