Fire hazard of textile materials based on polyester fibers for rail vehicles

Introduction. Wide application for the arrangement of passenger railcars (curtains, upholstery and covers of chairs and sofas, bedding) is occupied by fabrics made of fire-proof, chemically modified polyester fibers that meet ­foreign requirements. An experimental study of the parameters of fire hazard of such a fire-resistant textiles ac­cording to the Russian requirements to furnish railcars showed the impossibility of achieving normative criteria on the toxicity of combustion products and smoke-forming ability because of the peculiarities of the process of ­thermal decomposition. Therefore, an important task is to conduct a comprehensive research on the feasibility of establishing realistic numerical values of criteria of toxicity of products of combustion and smoke generation.

Problem of the issue. A feature of the thermal decomposition of polyethylene terephthalate (PET) is its ability to be in a viscous state at high temperatures. The most effective method of fire protection of PET fibers is chemical modification at the stage of their production due to the introduction of organophosphorus functional compounds in the synthesis process. Wide application in the construction of railcars, flameproof tissue is significantly hampered by their failure to comply with the requirements for smoke generation ability and toxicity index of combustion ­products.

Results and discussion. Introduction in the polymer chain of PET retardants that do not affect the conditions of tech­nological processing, possibly with their contents not more than 10 % by mass. This amount of flame re­tardant provides the material’s resistance to ignition and flame spread on the surface, lack of education burning melt, but does not alter significantly the toxicity index of combustion products and the rate of smoke generation. Experimental data on the toxicity of combustion products (the yield of CO and CO₂ in the mode of flaming combus­tion) flame retardant, low flame on the surface of the fabrics, flameproof polyester fibres. A comparison of the results of determination of toxicity index of products of combustion to the results of calculations of the generalized index of toxicity (CIT_g).

Conclusions. The criterion value of CIT_g (0.75) was established for evaluating the possibility of using textile materials in railway sleeping railcars, corresponding to the index of toxicity of combustion products from 34 to 52 mg/m³ (43 mg/m³ ± 20 %), which indicates the possibility of using fabrics with the index of toxicity of combustion products HCl₅₀ ≥ 35 mg/m³. Proposals have been developed to improve fire safety requirements for textile materials used in passenger railcars.

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