Study on a novel and efficient flame retardant synergist–nanoporous nickel phosphates VSB‐1 with intumescent flame retardants in polypropylene

Nanoporous nickel phosphate VSB‐1 was synthesized by hydrothermal method and its structure was characterized. Then VSB‐1 was added to the ammonium polyphosphate (APP) and pentaerythritol (petol) system in a polypropylene (PP) matrix for the first time, and the synergistic effect of VSB‐1 with intumescent flame retardants (IFR) was studied. With the addition of 2 wt% VSB‐1 and 23 wt% IFR, the LOI value of PP/IFR composites increased from 28.0 to 35.5. The UL‐94 test showed that PP with 20% IFR burned and had no rating, but with the addition of 2 wt% of VSB‐1 and 18% of IFR, it could reach V‐0 rating. The results of the X‐ray photoelectron spectroscopy (XPS) showed that the ratios of P/C and N/C of PP/IFR/VSB‐1 systems changed significantly from 0.133 to 0.205 (54% increase) and from 0.0328 to 0.047 (45.4% increase), respectively under 800°C for 10 min. Compared with the organophilic montmorillonite (OMT), 4 Å zeolite, and zinc tetraborate (ZB), VSB‐1 showed better synergistic effect at the same loading. Copyright © 2008 John Wiley & Sons, Ltd.