Influence of in‐situ growth of boron nitride with chestnut ball copper cobaltate synergistic ammonium polyphosphate on flame retardancy, smoke suppression, and thermal conductivity of polylactic acid

Abstract

Ammonium polyphosphate (APP) is generally used to prepare fire retardant polymer composites, but it is still a challenge to further improve its flame retardant efficiency. In this study, BN‐CuCo2O4 (BNCC) hybrid was successfully prepared by in‐situ growth of copper cobaltate (CC) on boron nitride (BN) by the hydrothermal method. It was added together with APP to polylactic acid (PLA) to prepare PLA composite materials. Investigations were performed into its influence on the composite's fire‐retardant ability and thermal conductivity. When 3 wt% BNCC and 12 wt% APP was added, the limiting oxygen index (LOI) of the PLA composite reached 31.7%, which was higher than that of pure PLA improved by 69.5% and it reached V‐0 rating of vertical combustion test (UL‐94). The cone calorimeter (CCT) test showed that the addition of 3 wt% BNCC and 12 wt% APP to PLA composites significantly increased both the residual char yield and the efficiency of suppressing smoke production compared to pure PLA and APP/PLA composites. BNCC could further improve its flame retardant efficiency of APP. The thermal conductivity test showed that BNCC further improved the thermal conductivity of PLA composites. Furthermore, the residual char and fire‐retardant mechanism of the composites was analyzed and intensive studied.