Study of crystal defects and spectroscopy characteristics of ammonium polyphosphate

Two kinds of commercial ammonium polyphosphate (APP) and three kinds of APP which were prepared in the laboratory were studied by X-ray diffraction (XRD), Fourier transforms infrared spectroscopy (FTIR), scanning electron microscopy (SEM) and transmission electron microscopy (TEM). In identification of the form II crystal APP by XRD and FTIR, some discrepancies were discussed. It is pointed out that the absorbance of the FTIR spectra at 682 cm^-1 can exist not only in the form I APP, but also in the form II APP with the crystal lattice defects. The SEM images indicate that the form II APP is of multilayer crystal structure. XRD and TEM can reveal the crystal lattice defects. Copyright Protection.