N-alkoxyamine-containing macromolecular intumescent flame-retardant-decorated ZrP nanosheet and their synergism in flame-retarding polypropylene

High-efficiency macromolecular intumescent flame retardant (MIFR) is urgently demanded but of great challenge. In this work, a novel N-alkoxyamine-containing MIFR-decorated zirconium phosphate (ZrP) nanosheet (denoted as RQMIFR-ZrP) was synthesized and combined with ammonium polyphosphate (APP) to endowed polypropylene (PP) with excellent flame retardancy. With the addition of 6.3 wt% RQMIFR-ZrP and 18.7 wt% APP, PP classed a UL-94 V-0 rating with a high LOI value of 39.5%. Moreover, the peak heat release rate, the total heat release, the peak of CO production, and the peak of CO2 production of PP/RQMIFR-ZrP/APP decreased by 94.0%, 83.2%, 91.3%, and 91.7%, respectively. It revealed that RQMIFR-ZrP not only generated nitroxyl radicals (NO center dot) to suppress the chain degradation of PP but also promoted to form high-quality intumescent char layers with the catalytic carbonization and layered barrier effect of ZrP nanosheet, which effectively prevented PP from burning. This work provides a new approach to preparing high-performance flame-retardant polymer.

Automated summary

A novel N-alkoxyamine-containing MIFR-decorated zirconium phosphate nanosheet was synthesized and combined with APP to endow PP with excellent flame retardancy. The addition of this new flame retardant system significantly reduced heat release rate and the production of CO and CO2, providing a new approach for preparing high-performance flame-retardant polymers.