The process of thermooxidation destruction of industrial butadiene-nitrile copolymers of the grades SKN-18, SKN-26 and substandard products is investigated. The process is carried out in aromatic solvents (toluene in the xylene) under the influence of air oxygen in the presence of an adduct of the radical initiator azodiisobutyronitrile with N-metilpirrolidone. The mass-average molecular weights of the resulting products were determined by gel permeation chromatography, and molecular weight distribution calculations were performed. The influence of the temperature and the content of the initiator on the change in the intrinsic viscosity of solutions of the resulting degradation products, depending on the time of the process, is considered. Based on a comparative analysis of the destruction parameters using toluene and xylene at 80 °C and an initiator concentration of 0.8% by weight. It was found that the type of solvent and the time of destruction practically do not affect the process of thermooxidative destruction with the production of low molecular weight polymers with a molecular weight of 40 ? 103. It is shown that in the course of the destruction of industrial rubbers differing in the content of acrylonitrile, the process proceeds with the formation of higher molecular weight compounds in rubbers with a higher content of acrylonitrile units. When carrying out the destruction of substandard rubber SKN-26SNT with high Defoe hardness, it is necessary to increase the concentration of the initiator to 1.1% of the mass. and temperature. The mechanism of thermooxidative destruction of the studied polymers is considered. According to the data of IR spectroscopy and chemical analysis, it was found that the products of thermooxidative destruction of nitrile butadiene rubbers contain oxygen-containing functional groups. Thus, a simple commercially method for producing low-molecular-weight butadiene-nitrile polymers based on special-purpose rubbers and substandard product with functional hydroxyl, carboxyl and epoxy groups has been developed.

1. Chernaya A.N., Nikulin S.S. Modification of petroleum polymer resin from the C9 fraction with maleic acid and its use for the protective treatment of wood. Chemical industry today. 2009. no. 4. pp. 28–33. (in Russian).

2. Papkov V.N., Gusev Yu.K., Rivin E.M., Blinov E.V. Butadiene-nitrile rubbers. Voronezh, FGBOU VPO "Voronezh State University of Engineering Technologies", 2014. 218 p. (in Russian).

3. Lonshakova T.I., Chernykh K.A., Utilin I.V. Thermal-oxidative destruction of diene rubbers by molecular oxygen in solution initiated by polymer oxidates. Chemistry and Computer Modeling. Butler messages. 2004. vol. 5. no. 2. pp. 63–67. (in Russian).

4. Tikhomirov S.G., Semenov M.E., Khaustov I.A., Bityukov V.K. et al. Control and prediction of quality parameters of polymers in the process of their destruction in solution. Theoretical foundations of chemical technology. 2018. vol. 52. no. 4. pp. 466–472. (in Russian).

5. Obrecht W., Muller Ju.M., Nuyken O. Process for the metathetic degradation of nitrile rubber. Patent US, no. US 2009076227 A1, 2009.

6. Ong C., Mueller Ju.M., Soddemann M., Koenig T. Metathesis of nitrile rubbers in the presence of transition metal catalysts. Patent US, no. US 20120329941 A1, 2012.

7. Obrecht W., Ong C., Miller J.M., Nuyken O. Process for degrading nitrile rubbers in the presence of catalysts having an increased activity. Patent US, no. US 8609782 B2, 2013.

8. Shekhavtsova T.N., Shatalov G.V., Shestakov A.S., Papkov V.N. Thermal-oxidative destruction as a method for obtaining low-molecular polydiene polymers. Rubber and rubber. 2018. vol. 77. no. 6. (in Russian).

9. Shekhavtsova T.N., Shatalov G.V., Shestakov A.S., Papkov V.N. Obtaining low molecular weight functionalized polymers by thermooxidative degradation of stereoregular polybutadiene. Condensed media and interfacial boundaries. 2016. vol. 18. no. 3. pp. 414–421. (in Russian).

10. Karaseva S.Ya., Zhabina A.A. Chemistry and technology of macromolecular compounds. 2015. (in Russian).

11. Sokolova M.D., Fedorova A.F., Davydova M.L. Influence of 6PPD Stabilizer on Climatic Stability of Rubbers Based on Butadi-ene-Nitrile and Epichlorohydrin Rubbers. Materials Science Forum. Trans Tech Publications Ltd, 2019. vol. 945. pp. 433-437. doi: 10.4028/www.scientific.net/MSF.945.433

12. Davydova M.L., Fedorova A.F. Research changes in the properties of butadiene-nitrile rubber under various aging conditions. Journal of Elastomers & Plastics. 2021. pp. 00952443211029036. doi: 10.1177/00952443211029036

13. Wang X., Chen D., Zhong W., Zhang L. et al. Experimental and theoretical evaluations of the interfacial interaction between carbon nanotubes and carboxylated butadiene nitrile rubber: Mechanical and damping properties. Materials & Design. 2020. vol. 186. pp. 108318. doi: 10.1016/j.matdes.2019.108318

14. Shadrinov N.V., Borisova A.A. Thermophysical and Dynamic Properties of Nitrile Butadiene Rubber Filled with Ultra-High Mo-lecular Weight Polyethylene. Inorganic Materials: Applied Research. 2021. vol. 12. no. 4. pp. 1112-1119. doi: 10.1134/S2075113321040389

15. Bochkarev E.S., Vostrikov D.S., Tuzhikov O.O. Ozone Resistance of Vulcanizates Based on XNB Rubber. Defect and Diffu-sion Forum. Trans Tech Publications Ltd, 2021. vol. 410. pp. 686-691. doi: 10.4028/www.scientific.net/DDF.410.686

16. Fedorova A.F., Davydova M.L., Sokolova M.D., Pavlova V.V. The Effect of Phenolic Antioxidants on the Nominal Tensile Strength of Nitrile Butadiene Rubbers during Full-Scale Exposure. Polymer Science, Series D. 2021. vol. 14. no. 2. pp. 312-317. doi: 10.1134/S1995421221020064

17. Dubkov K.A., Panov G.I., Parmon V.N. Nitrous oxide as a selective oxidant for ketonization of C= C double bonds in organic compounds. Russian Chemical Reviews. 2017. vol. 86. no. 6. pp. 510.

18. Yan H., Li H., Li W., Fan X. et al. Probing the Damping Property of Three?Dimensional Graphene Aerogels in Carboxylated Nitrile Butadiene Rubber/Polyurethane Blend. Polymer Engineering & Science. 2020. vol. 60. no. 1. pp. 61-70. doi: 10.1002/pen.25259

19. Zuleta E.C., Baena L., Rios L.A., Calder?n J.A. The oxidative stability of biodiesel and its impact on the deterioration of metallic and polymeric materials: a review. Journal of the Brazilian Chemical Society. 2012. vol. 23. no. 12. pp. 2159-2175.

20. Wei X., Wu H.L., Zhang L.W., Zhang S.Y. et al. Failure Analysis of Nitrile Rubber O-Rings Static Sealing for Packaging Barrel. Journal of Failure Analysis and Prevention. 2018. vol. 18. no. 3. pp. 628-634. doi: 10.1007/s11668-018-0451-3