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The characteristics of thermooxidative degradation of materials made of cellulose (cotton) and polyester fibre blend are established, consisting of alteration of the dynamics and temperature range of liberation of combustible gases and reducing the self-ignition temperature. It is shown that T-3 fireproofing compound is an effective combustion retardant for materials made of cellulose and polyester fibre blends, since it inhibits oxidative processes in the self-ignition temperature range of combustible products and has high carbonizing power.A high burning rate is inherent in materials made of cotton and polyester blends. This is because the polyester in the blend belongs to the category of highly flammable compounds that burn with release of a large amount of heat [1]. In addition, the carbonized residue (CR) of the cellulose constituent formed in thermolysis creates favorable conditions for burning, as it is the skeleton that retains drops of the thermoplastic polymer melt in the flame zone. For this reason, reducing the combustibility of cotton and polyester materials is a complex problem.One of the basic requirements imposed on flame retardants (FR) is decomposition in the temperature range of decomposition of the modified polymer [2]. Since intensive decomposition of cotton takes place in the 250-350°C temperature region and polyester decomposes at 380-450°C, flame retardants used to reduce the combustibility of materials made from a blend of cotton and polyester must inhibit thermooxidative processes in a relatively wide temperature range that coincides with decomposition of the fibre blend.We used thermogravimetric analysis to investigate thermolysis of materials with a different cotton and polyester content to find the temperature range of their decomposition, which determines the selection of effective FR.It follows from the data in Table 1 that increasing the polyester content in a blend to 50% decreases the maximum rate (υ max ) of weight loss by the cotton constituent to 17.8%/min. A further decrease in the cotton content in the material to 35% decreases the rate of decomposition to 16.5%/min, while the maximum rate of thermooxidative decomposition of cotton is 63.7%/min.The polyester underwent insignificant changes in the basic stage of thermal decomposition of fabric made of the indicated fibre blend at 250-400°C, i.e., in the region of intensive decomposition of the cellulose constituent.As a consequence, the presence of the polyester constituent in the blend slows thermooxidation of the cotton. This is due to the fact that the polyester melt coats the cotton fibres, preventing liberation of volatile products of thermooxidative decomposition of the cellulose.Thermolysis of the thermoplastic constituent in the 400-500°C temperature region also takes place at a lower rate. This could be because thermooxidative decomposition of cellulose in the indicated region is accompanied by an endothermic effect and oxidative processes are slowed as a result.

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