A novel flame retardant containing calixarene and DOPO structures: Preparation and its application on the fire safety of polystyrene

A novel flame retardant (FR) containing phosphorus and calixarene structures was synthesized, and the FR combined with ammonium polyphosphate (APP) was then incorporated into polystyrene (PS). The flame retardancy and thermal stability of the flame retardant composites were investigated. The limiting oxygen index can reach 21.0% when the mass ratio of FR/APP was 3:2. Char residues at 650 degrees C in an air atmosphere increased from 2.2% to 21.5% notably when FR/APP was incorporated into PS matrix, indicating an improvement of thermo-oxidation resistance. Compared to the virgin PS and FR/PS composites, the peak heat release rate of FR/APP/PS composites is reduced to 259.87kW/m(2) (PS8), indicating synergistic flame retardant effects between FR and APP. Generally, stable char layer of FR/APP/PS is responsible for the improved flame retardant properties, which not only effectively prevented the release of combustion gases but also protect the interior substrate from oxygen and heat permeation.