Synergestic Effects of Zinc hydroxystannate on the Flame retardancy and Thermal degradation of Intumescent Flame-Retardant Polypropylene

摘要

The flammability and thermal degradation properties of polypropylene (PP) composites containing zinc hydroxystannate (ZHS) and intumescent flame retardant additives (IFR), i.e. ammonium polyphosphate (APP) and pentaerythritol (PER) were characterized respectively by limiting oxygen index (LOI), UL 94 measurements and thermogravimetry analysis in this work. A synergistic effect in flame retardancy was observed when ZHS was used in combination with APP and PER. The experimental data indicated that ZHS enhanced the LOI value. The PP/IFR composites passed the UL-94 V-0 rating test in the presence of lwt% ZHS. The TGA results showed that ZHS could accelerate the char formation of IFR, therefore, greatly increase the thermal stability of PP composites. The FTIR spectra revealed that the flame retardant mechanism of ZHS could be ascribed to its catalysis degradation of the PP resin, which promoted the formation of charred layers with the P-O-P and P-O-C complexes in the condensed phase. SEM observation further indicated that ZHS could promote forming the stable and folded intumescent char layer and effectively protect the underlying polymer from burning.