Synergistic effect of phosphorus, nitrogen, and silicon on flame-retardant properties and char yield in polypropylene

In this study, several flame retardants (FRs), containing phosphorus, nitrogen, and silicon, were synthesized. These synthesized FRs were blended with polypropylene (PP) to obtain mixture samples. The flame-retardant properties of these mixture samples,were estimated by the limiting oxygen index (LOI) value and thermal stabilities were characterized by thermogravimetric analysis. The LOI values of these samples were improved from 17.0 to 26.0 and the char yield increased from 0 to 27 wt %. A comparison of these samples, with respect to their LOI values and carbon yield, showed that the FRs, which simultaneously contained phosphorus, nitrogen, and silicon elements, can provide materials with the best flame-retardant properties, suggesting that there is a synergistic effect among the three elements on the flame-retardant properties and char yield when they are used in PP. (c) 2005 Wiley Periodicals, Inc.