An investigation of the flame retardation mechanism of polypropylene containing a chlorine flame retardant system by XPS(ESCA)

The flame-retarding mechanism of polypropylene containing a chlorine system has been explored by XPS(ESCA). A wealth of information, such as chemical states of chlorine and antimony in the surface as a function of temperature were obtained, some of which was obtained previously by techniques associated with the bulk properties. In contrast to the thermal analysis techniques, a discussion of the synergistic effect between chlorine and antimony was put forward on the basis of Cl−1 in the surface. The instability of metallic antimony in the surface was also revealed by the absence of Sb0 from Sb3d spectra. It should be emphasized that XPS, properly used, may be of great importance in formulation design, i.e. the match of polymers and flame retardants for technological control.