Flame retardant polymethyl methacrylate toughened by a phosphorus-containing vitrimer

The flammability of poly (methyl methacrylate) (PMMA) poses a fire safety hazard to its applications. A hybrid of piperazine pyrophosphates (PAPP) and aluminum diethylhypophosphate (ADP) were used to modify the flame retardancy of PMMA, and a phosphorus-containing vitrimer (V) was incorporated to toughen the PMMA blends. The PMMA containing 20 wt% PAPP/ADP achieves the UL-94 V0 rating with an increased limiting oxygen index (LOI) value of 24.3 vol%. After incorporating 2.0 wt% V into flame retardant PMMA, both the UL-94 V0 rating and an increase of 56 % for the impact strength of PMMA blends are obtained. The gas-condensed hybrid effects of ADP/PAPP modify the flame retardancy of PMMA and the transesterification between vitrimer and PMMA enhances its mechanical properties. This provides a feasible method to prepare PMMA blends with good comprehensive performances.