The Synergistic Effect of Anhydrous Magnesium Carbonate and Eco-Friendly Inorganic Flame Retardants on Soft Polyvinyl Chloride Composites

Graphical The graphical abstract illustrates that incorporating a synergistic system of AMC, MH, and ATH significantly enhances the flame retardancy and smoke suppression of SPVC. Unmodified SPVC shows intense burning and heavy smoke, while the ternary system reduces flame intensity and smoke release through endothermic decomposition, gas dilution, and protective char formation. The use of inorganic fillers to enhance the flame retardant properties of soft polyvinyl chloride (SPVC) often results in a trade-off with mechanical properties due to the relatively high filler content and inadequate dispersion within the polymer matrix. In this study, the combined synergistic effects of different inorganic flame retardants were explored to improve both flame retardancy and mechanical performance of SPVC simultaneously. First, the impact of anhydrous magnesium carbonate (AMC) content on the flame retardant and mechanical performance of SPVC was investigated. Results indicated that 60AMC/SPVC composites achieved the limiting oxygen index of 28.00% and a UL-94 rating of V-0. Additionally, the peak heat release rate showed a marked reduction of 38.75%, and the peak smoke production rate was reduced to 0.037 m 2 /s compared to SPVC. Second, the combined impacts of compound magnesium hydroxide, aluminum trihydrate, and AMC on flame retardancy and mechanical performance were investigated. The results demonstrated that compound SPVC composites exhibited a residual carbon content of 26.68%, approximately 1.5 times that of SPVC as magnesium hydroxide (MH), aluminum hydroxide (ATH), and AMC were added in equal proportions (1:1:1). The strategic use of inorganic fillers offers a straightforward and efficient approach for industrially preparing flame retardant SPVC composites.