Burning plastics: Mechanisms of smoke formation

Abstract

Abstract-Quantitative pyrolysis gas chromatography studies have been conducted on three grades of crosslinked polyester resin formulated for improved resistance to surface spread of flame. Pyrolysis temperatures from 723 to 1273 K were used, and these values correspond to 'surface' temperatures of materials exposed to heat fluxes of 15-149 k W m-2 which are typical of conditions experienced in real fires. Comparison is made with earlier macro studies on the evolution of smoke from plastics materials exposed to similar heat fluxes under an inert atmosphere. There is some correlation between the smoke obscuration data obtained in previous macro studies and the yield of volatile aromatic products evolved on pyrolysis. The presence of flame retardants increases the formation of carbon in the pyrolysis residue and decreases the yield of volatile aromatic products isolated. The results are considered in the context of mechanisms of smoke formation.

Thermal degradation of polyester thermosets prepared using dibromoneopentyl glycol

“…The lack of reproducibility of chromatograms obtained from pyrolysis experiments has also been observed by others. Green et al 24 reported the coefficients of variation to be in the general range of 2-12% but as high as 10-20% for certain flame-retarded polyester for- mulations. Similarly, May and co-workers28 reported coefficients of variation of 0.9-12% in a study of the pyrolysis of paint samples, which changed to 5.5-32.9% when a drifting baseline was involved.…”

“…The lack of reproducibility of chromatograms obtained from pyrolysis experiments has also been observed by others. Green et al 24 reported the coefficients of variation to be in the general range of 2-12% but as high as 10-20% for certain flame-retarded polyester for- The use of a capillary OV 101 column for the analysis of the volatiles enabled separation of the majority of the degradation products in a single run and eliminated the need for several columns. Degradation of the 20% bromine DBNPG polyesters at 530°C in air produced a mixture of organic products which gave rise to well over a 100 peaks in the capillary column chromatogram at maximum sensitivity.…”

Polyesters: A review of the literature on products of combustion and toxicity

“…Both fire retarded and non-fire retarded fiber glass reinforced polyesters were tested. The results (Tables [17][18][19] showed that the fire retarded material was more toxic based on the estimated LC,, values (Table 20). In both the vented and nonvented tests the toxicity of the fire retarded polyester was similar to that of Douglas fir, which was greater than the non-fire retarded polyester.…”

Polyesters :

“…Non-flaming combustion was achieved by an electrical radiant heater, while flaming combustion used four small butane burners. Exposures were vented (i.e., 8 1/min of fresh air were mixed continuously with the combustion products to total a circulation flow rate through both chambers of 16 15,16,17) showed that the fire retarded material was more toxic based on the estimated LC^q values (Table 18). In both the vented and non-vented tests, the toxicity of the fire retarded polyester was similar to that of Douglas fir which was greater than the non-fire retarded polyester.…”

“…Hilado [39,40,41,42,43,44] also found polyester to be more toxic than cotton and a flame retarded poly- [16] Green [17] (°K) ( [18] 900°C [18] 900°C [19] Carbon Not detected.…”