Preparation, Thermal Degradation, and Fire Behaviors of Intumescent Flame Retardant Polypropylene with a Charring Agent Containing Pentaerythritol and Triazine

A macromolecular charring agent named as PEPADC was synthesized by using cyanuric chloride, 2,6,7-trioxa-l-phosphabicyclo[2.2.2]octane-4-methanol (PEPA), and diethylenetriamine and used to prepare intumescent flame retardant polypropylene (IFR-PP) containing ammonium polyphosphate (APP). The effect of flame retardant compound on thermal degradation, flame retardancy, and fire behavior properties of a IFR-PP system has been investigated. The results suggested that the max thermal degradation temperature (Tmax) as well as char residue at 700 °C increased with IFR loading. The highest LOI value of IFR-PP is 35.5, while the IFR loading is 30 wt % and the weight ratio of APP to PEPADC is 4:1. Meanwhile, the IFR-PPs can pass UL-94 V-0 when the weight ratio of APP to PEPADC is between 1:2 and 5:1. Cone calorimetry results indicated that IFR-PPs exhibited much lower heat release rate (HRR), total heat release (THR), specific extinction area (SEA), and total smoke production (TSP) than the neat PP.