The combustion and pyrolysis process of flame-retardant polystyrene/cobalt-based metal organic frameworks (MOF) nanocomposite

Considerable toxic gases and high temperature smoke will be generated during the combustion of polystyrene (PS), which restricts its application. Here, a cobalt-based MOF-71-NH2 (hereinafter referred to as MOF-NH2) has been synthesized and further modified with phosphonitrilic chloride trimer (PCT) by a post-synthesis modification (PSM) strategy, named as PCT@MOF-NH2, which was used to enhance the flame retardancy of PS. Desirable results were obtained as expected: the fire safety and tensile strength of PS were prominently improved after adding PCT@MOF-NH2. Compared with pure PS, there were more than 40% and 31% decreases in the value of pHRR and THR with 3.0 wt% content of PCT@MOF-NH2. From the analysis of gaseous and condensed products after combustion, the possible flame retardancy mechanism of PS nanocomposites can be attributed to the barrier effect of PCT@MOF-NH2, which provides a promising application field of MOFs to improve flame retardation of polymer materials.