| Abstract: | The thermal decomposition products that evolve from mixtures of poly(vinyl chloride) (PVC), poly(vinylidene chloride) (PVC2), and chlorinated paraffin (CP) with Sb2O3 and (BiO)2CO3, respectively, have been analyzed by a method of direct pyrolysis in the ion source of a mass spectrometer. This method allowed us to detect volatile products with masses as high as 226 (SbCl3), 314 (BiCl3), 484 (Sb4), 580 (Sb4O6), and 836 (Bi4). Except for SbCl3, this is the first direct evidence of the presence of these species in the gas phase. The volatilization rate profiles of these species versus the pyrolysis temperature have been also determined. Our data confirm that the effectiveness of the title mixtures as flame-retardant agents depends on the transport of volatile metal products in the flame and provide direct evidence of the presence of metallic Sb and Bi below the polymer ignition temperatures. |
