Study of Pyrolysis Gaseous Products of Various Fibers-Relationship between Pyrolysis Products and Flame Retardancy

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Pyrolysis of cotton, silk and wool fabrics was studied by Curie-point pyrolysis-gas chromatography (Py-GC) and Curie-point pyrolysis-gas chromatography-mass spectrometry (Py-GC-MS). The pyrolysis temperature for cotton samples was set 590ﾟC while that for wool and silk samples were 794ﾟC.A Py-GC chromatogram of the untreated cotton showed the formation of levoglucosan, a key intermediate in the pyrolysis of cellulose. Cotton samples treated with phosphorus flame retardants gave less levoglucosan. Moreover, the total amount of the volatile pyrolysis products decreased with increase in the phosphrus contents of the treated cotton samples. These values obtained by Py-GC were consistent with the flame retardancy attained by the treatment.Characteristic pyrolysis products from both silk and wool samples were hydrogen cyanide, acetonitrile and acrylonitrile all of which contain nitrogen. In addition to those, wool samples gave sulfur-containing hydrogen sulfide, carbonyl sulfide and methyl mercaptan by pyrolysis. Silk and wool samples treated with bromine or N-bromosuccinimide yielded bromine-containing bromomethane, bromoethane, bromophenol and bromocresol. The total amount of pyrolysis products samples decreased by the treatments. In conclusion it is demonstrated in this work that Py-GC and Py-GC-MS analyzes of chemically treated fibers are a useful tool for the evalution of flame retardancy of the treated fibers and the structural analysis of the chemically modified fibers.