Synergistic effect of nickel formate on the thermal and flame-retardant properties of polypropylene

Nickel formate was used as a catalyst to improve the flame-retardancy of intumescent systems based on ammonium polyphosphate (APP) and pentaerythritol (petol) in polypropylene (PP). Limited oxygen index (LOI), X-ray diffraction (XRD) and thermogravimetric analysis (TGA) were used to characterize the fire-retardancy and thermal stability of the PP system and the microstructure of the burned residue. The catalytic effect was shown in an increase in LOI, and a change in the residue microstructure and the thermal stability of the PP system. LOI increased with the concentration of the catalyst in the range 0.1-5 wt% of the composition until a maximum was reached. At higher concentration of the catalyst a decrease in the LOI was observed. (c) 2005 Society of Chemical Industry.