Metal functionalized POSS as fire retardants in polypropylene

This paper deals with the study of the combustion properties of dimeric and oligomeric Al-and Zn-isobutyl silsesquioxane (POSS)/polypropylene (PP) composites, in comparison with neat PP and PP/octaisobutyl POSS.The presence of Al-POSS leads to a decrease in combustion rate with respect to PP, resulting in a decrease of Heat Release Rate (−43% at 10 wt% POSS loading) as well as reduction in CO and CO₂ production rates, whereas a negative effect on the above parameters is obtained with octaisobutyl POSS. Zn-POSS does not significantly affect the PP combustion behaviour.The effect of Al-POSS is most likely related to its chemical activity, which favours the formation of a moderate amount of char residue, by catalysing secondary reactions in the polymer during combustion.