Thermal Stability and Flame Retardancy of Polypropylene with Phosphorus, Nitrogen and Silicon-Containing Compounds

Abstract

Flame retardants containing phosphorus, nitrogen and silicone elements have been synthesized. The thermal stabilities of polypropylene (PP), PSiN and PP/PSiN have been studied by thermogravimetric (TG) analysis in nitrogen, air and oxygen atmospheres. The initial decomposition temperature (IDT), maximum-rate degradation temperature (Tmax), integral procedure decomposition temperature (IPDT) and char yield at 800 °C in various atmospheres have been investigated. Although the IDT of PP was reduced by the introduction of PSiN, the Tmax, IPDT and char yield were all increased. The flame retardancy of PP/PSiN composites were evaluated by measuring their Limiting Oxygen Index (LOI) values. Their thermal stabilities agreed with the results of the flame retardancy tests: the PP/PSiN-A exhibited good flame retardancy with LOI of 26.0 and its char yields at 800 °C were 27 wt.% (in nitrogen), 12 wt.% (air) and 12 wt.% (in oxygen). The activation energies of PP, PSiN and PP/PSiN composites in various atmospheres were calculated using the method of Horowitz-Metzger.