Synergistic effects of hydroxy silicone oil on intumescent flame retardant polypropylene system

The effects of hydroxy silicone oil (HSO) as a synergistic agent on the flame retardancy of intumescent flame retardant polypropylene composites (IFR-PP) were studied, and the IFR system mainly consisted of the ammonium polyphosphate (APP) and pentaerythritol (PER). The UL-94 test, thermogravimetric analysis (TGA), cone calorimeter (CONE), digital photograph and X-ray photoelectron spectroscopy (XPS) were used to evaluate the synergistic effects of hydroxy silicone oil. It has been found that the Polypropylene (PP) composite containing only APP and PER does not show good flame retardancy at 30% additive level. The cone calorimeter results show that the heat release rate, mass, total heat release, carbon monoxide and carbon dioxide of PP/APP/PER/HSO composites decrease in comparison with the PP/APP/PER ternary composite. The digital photographs demonstrated that HSO could promote to form the homogenous and compact intumescent char layer. Thus, a suitable amount of HSO plays a synergistic effect in the flame retardancy. (C) 2009 Elsevier Ltd. All rights reserved.