Investigation on pyrolysis of intumescent flame-retardant polypropylene (PP) composites based on synchrotron vacuum ultraviolet photoionization combined with molecular-beam mass spectrometry

The pyrolysis of intumescent flame-retardant polypropylene (PP) composites was studied by synchrotron vacuum ultraviolet photoionization combined with molecular-beam mass spectrometry (SVUV-PIMS). Pyrolytic products of intumescent flame-retardant PP composite formed at certain temperature have been identified by the measurement of photoionization mass spectra at different photon energies. By using SVUV-PIMS, some isomers were identified. Meanwhile, the effect of high-efficient flame-retardant synergist–nanoporous nickel phosphate on pyrolytic products of intumescent flame-retardant PP composite was also studied. By analyzing the pyrolysis of the intumescent flame-retardant PP composites with or without the flame-retardant synergist, the synergistic flame-retardant mechanism was discussed as the condensed-phase flame-retardant mechanism not gas flame-retardant mechanism as expected. The studies in this work are much helpful for further understanding the flame-retardant mechanism of intumescent flame-retardant PP composites.