MoO3-ZrO2 solid acid for enhancement in the efficiency of intumescent flame retardant.

Abstract To further improve the efficiency of intumescent flame retardant (IFR) system consisting of ammonium polyphosphate and charring-foaming agent, MoO 3 -ZrO 2 solid acid is used as an adjuvant. The influence of MoO 3 -ZrO 2 on the thermal decomposition, reaction to small flame and fire behavior of polypropylene (PP)/IFR composite is investigated. The incorporation of 1 wt% solid acid results in the enhanced limiting oxygen index (LOI) and fire safety of PP/IFR composite, while decreasing its peak heat release rate from 431 to 370 kW/m2. Flame retardant mechanism is proposed based on the analysis of thermal decomposition behavior and char residue. The yield and graphitization degree of char residue are improved by MoO 3 -ZrO 2. The release of CO 2 from thermal decomposition of IFR is accelerated by this solid acid. This work provides a new path to designing highly fire retardant polymer composites. Graphical abstract Unlabelled Image Highlights • The efficiency of IFR was enhanced by MoO 3 -ZrO 2 solid acid. • Thermal stability and pyrolysis behavior were investigated by TGA and TG-IR. • Flame retardant mechanism of APP/CFA/MoO 3 -ZrO 2 system was concluded. [ABSTRACT FROM AUTHOR]