Effect of Catalytic Synergism of Bimetallic Centers on the Flame Retardant and Smoke Suppressing Properties of Flexible Polyvinyl Chloride.

In this study, we synthesized a layered double hydroxide (LDH) with bimetallic centers of copper and iron (CuFe-LDH) and employed it as a multifunctional flame retardant and smoke suppressant to enhance the flame retardancy and smoke suppression properties of polyvinyl chloride (PVC). The results indicate that during the combustion of the CuFe-LDH/PVC composite, a dense carbon layer with tortuous pathways forms in the condensed phase through Lewis acid-catalyzed and reduction-coupling mechanisms. Coupled with the dilution effects of H₂O and CO₂ during combustion, the CuFe-LDH/PVC composite exhibits remarkable flame retardant and smoke suppressant properties, achieving a limiting oxygen index value of 34.8% and achieving a UL-94 V-0 rating. Compared to pristine PVC, the peak heat release rate of the CuFe-LDH/PVC composite was reduced by 20.55%, and the maximum average rate of heat emission decreased by 27.9%. Furthermore, the maximum smoke density and maximum average rate of smoke emission were reduced by 36.5% and 67.8%, respectively. This research proposes a novel method for designing and synthesizing additives that enhance the flame retardancy and smoke suppression performance of PVC from a catalytic perspective while avoiding the formation of multi-phase interfaces, thereby alleviating the adverse effects of traditional co-addition methods on polymers.