Effect of polysiloxane and silane‐modified SiO2 on a novel intumescent flame retardant polypropylene system

Abstract The effects of polysiloxane and silane‐modified SiO 2 (M‐SiO 2 ) on properties of intumescent flame retardant polypropylene (IFR‐PP) have been studied. The results demonstrate that both polysiloxane and M‐SiO 2 could effectively enhance the flame retardancy of the IFR‐PP, despite only 20 wt% loading of IFRs. Remarkably, the polysiloxane can clearly improve the water resistance of IFR‐PP. It can obtain UL‐94 V‐0 rating, and its LOI remains over 34% after the water treatment. The surface tension data, XPS data, and SEM sufficiently prove that the some of polysiloxane transfers to the IFR‐PP surface during processing. The TGA data show that the polysiloxane more effectively enhances the thermal stability of the IFR‐PP at high temperature and increases the char residue. The CONE results reveal that the polysiloxane can clearly change the decomposition behavior of PP and markedly reduce flammability parameters. The homogenous and compact intumescent char layers further confirm that polysiloxane is a very effective silicon‐containing additive for the flame retardancy and water resistance of the IFR‐PP. Copyright © 2010 John Wiley & Sons, Ltd.