Abstract: Into a flame retardant polypropylene composites containing poly (ethylene urea-formaldehyde) and ammonium polyphosphate, a small amount of magnesium stannat was introduced as a synergetic flame retarding agent. The flame retardant properties and the resultant char layers of the composites were studied through cone calorimeter, TG, FTIR, SEM, and EDX energy spectroscopy. The measured results showed that a loading of 1wt% magnesium stannate increased combustion residue, improved the quality of char layers, and led to higher efficiency of flame retardancy, in addition, the burning time with flame was prolonged from 415s to 805s. Upon loaded with 1wt% of magnesium stannate, for reaching a level of UL-94 V-0, the loading of flame retardant decreased from 32% to 28%, limited oxygen index rose from 33.4% to 35.1%, tensile strength of the composites increased from 24.3MPa to 26.0MPa, elongation at break increased from 23% to 45%, compared with devoid systems.

Key words: Magnesium stannat, Intumescent flame retardant, Polypropylene, Synergetic effect