Flame-retardant effects of cyclic phosphonate with HALS and fumed silica in polypropylene

Abstract

In this study, an N-alkoxy-hindered amine-based UV stabilizing agent (NOR-116) and nanosized silica particles (Aerosil R-972) were combined with a cyclic phosphonate based-flame retardant (FR; PCO-900) and incorporated into polypropylene via melt extrusion in a microcompounder. In order to stimulate the conditions in the favor of further processing such as fiber spinning, the content of additives in polypropylene was kept low (up to 6.5 wt %). The effects of the PCO-900, alone and in combination with NOR-116 and Aerosil-R972, on the flammability and thermal stability of polypropylene were evaluated by limit oxygen index (LOI) tests, cone calorimetry, and thermogravimetric analysis. The proposed system with 3.5 wt % PCO-900/1.5 wt % NOR-116/1 wt % Aerosil-R972 decreased the heat release, increased the LOI and thermo-oxidative stability, and, thus, improved the fire resistance of polypropylene. The possible mode of FR activity was also discussed based on the analysis