Mechanistic study on flame retardance of polycarbonate with a small amount of potassium perfluorobutane sulfonate by TGA-FTIR/XPS

The work focuses on a mechanistic study of the title system with the aid of both TGA-FTIR (in the gas phase) and XPS (in the condensed phase). It is concluded that: (1) although the change in yield of char for PC/PPFBS is insignificant with respect to PC itself it appears that the majority of the crucial FR activity is in the condensed phase as indicated by the XPS data; (2) TGA-FTIR experiments support the view that the degradation of polycarbonate proceeds by the cleavage of the Cα-O and the Cβ-H bonds, leading to the formation of dienes, diols and carbon dioxide; (3) the reverse reaction of the intermediates, like phenols, may occur via the basic catalyst, possibly K-alkyl oxide, a weaker base is generated in the process; (4) voluminous evolution of CO2 accelerated by PPFBS may give flame retardance by way of intumescent action and its dilution into the gas phase.