From Chemistry Towards Technology Step-By-Step From Chemistry Towards Technology Step-By-Step От химии к технологии шаг за шагом 2782-1900 89180 10.52957/2782-1900-2024-5-3-91-103 Научные статьи Scientific articles Научные статьи The effect of the isocyanate trimerisation catalyst on the chemical composition and strength characteristics of polyurethane-polyisocyanate foams The effect of the isocyanate trimerisation catalyst on the chemical composition and strength characteristics of polyurethane-polyisocyanate foams https://orcid.org/0000-0001-7738-7600 Власов Руслан Романович Vlasov Ruslan Romanovich vlasovruslan.hs@yandex.ru Зайцев Сергей Дмитриевич Zaycev Sergei Dmitrievich szay@inbox.ru

доктор химических наук;

doctor of chemical sciences;

 Нижегородский государственный университет им. Н.И. Лобачевского Нижний Новгород Россия Lobachevsky State University of Nizhny Novgorod Nizhny Novgorod Russian Federation Нижегородский государственный университет им. Н.И. Лобачевского the Leading and National Research Nizhigorodsky State University named after N.I. Lobachevsky 24 09 2024 24 09 2024 5 3 91 103 29 05 2024 02 07 2024 https://chemintech.ru/en/nauka/article/89180/view

Nowadays polyurethane-polyisocyanurate (PIR) foams are in a wide use as structural and thermal insulation materials. Isocyanate trimerisation catalysts for foams synthesis have low selectivity in terms of isocyanurate formation. As a consequence, a significant number of target (primary) and (secondary) chemical processes occur during the synthesis of PIR foams. We estimated the dependence of isocyanate group consumption for the formation of the main primary and secondary products on composition isocyanate index by methods based on the internal standard. Indeed, with an increase in the isocyanate index, the conversion of isocyanate to isocyanurate decreases significantly. The paper examines the influence of trimerisation catalyst type on chemical composition and strength characteristics of PIR foams. Hence, catalysts based on organic salts of alkali metals are more selective to the isocyanate trimerisation process than tertiary amines and derivatives of quaternary ammonium bases.

Nowadays polyurethane-polyisocyanurate (PIR) foams are in a wide use as structural and thermal insulation materials. Isocyanate trimerisation catalysts for foams synthesis have low selectivity in terms of isocyanurate formation. As a consequence, a significant number of target (primary) and (secondary) chemical processes occur during the synthesis of PIR foams. We estimated the dependence of isocyanate group consumption for the formation of the main primary and secondary products on composition isocyanate index by methods based on the internal standard. Indeed, with an increase in the isocyanate index, the conversion of isocyanate to isocyanurate decreases significantly. The paper examines the influence of trimerisation catalyst type on chemical composition and strength characteristics of PIR foams. Hence, catalysts based on organic salts of alkali metals are more selective to the isocyanate trimerisation process than tertiary amines and derivatives of quaternary ammonium bases.

 polyurethane-polyisocyanate foams isocyanate trimerisation secondary chemical reactions isocyanate to isocyanurate conversion residual isocyanate allophanate carbodiimide compressive strength polyurethane-polyisocyanate foams isocyanate trimerisation secondary chemical reactions isocyanate to isocyanurate conversion residual isocyanate allophanate carbodiimide compressive strength

Das A., Mahanwar P. A brief discussion on advances in polyurethane applications // Advanced Industrial and Engineering Polymer Research. 2020. Vol. 3. Issue 3. pp. 93-101. DOI: 10.1016/j.aiepr.2020.07.002. Available at: https://www.sciencedirect.com/science/article/pii/S2542504820300269 (accessed 10.06.2024). Das A., Mahanwar P. A brief discussion on advances in polyurethane applications // Advanced Industrial and Engineering Polymer Research. 2020. Vol. 3. Issue 3. pp. 93-101. DOI: 10.1016/j.aiepr.2020.07.002. Available at: https://www.sciencedirect.com/science/article/pii/S2542504820300269 (accessed 10.06.2024). Stirna U., Beverte I., Yakushin V., Cabulis U. Mechanical properties of rigid polyurethane foams at room and cryogenic temperatures // Journal of Cellular Plastics. 2011. Vol. 47. Issue 4. pp. 337-355. DOI: 10.1177/0021955X11398381. Available at: https://journals.sagepub.com/doi/10.1177/0021955X11398381 (accessed 10.06.2024). Stirna U., Beverte I., Yakushin V., Cabulis U. Mechanical properties of rigid polyurethane foams at room and cryogenic temperatures // Journal of Cellular Plastics. 2011. Vol. 47. Issue 4. pp. 337-355. DOI: 10.1177/0021955X11398381. Available at: https://journals.sagepub.com/doi/10.1177/0021955X11398381 (accessed 10.06.2024). Kim S. H., Kim B. K., Lim H. Effect of isocyanate index on the properties of rigid polyurethane foams blown by HFC 365mfc // Macromolecular Research. 2008. Vol. 16. Issue 5. pp. 467-472. DOI: 10.1007/BF03218546. Available at: https://link.springer.com/article/10.1007/BF03218546 (accessed 10.06.2024). Kim S. H., Kim B. K., Lim H. Effect of isocyanate index on the properties of rigid polyurethane foams blown by HFC 365mfc // Macromolecular Research. 2008. Vol. 16. Issue 5. pp. 467-472. DOI: 10.1007/BF03218546. Available at: https://link.springer.com/article/10.1007/BF03218546 (accessed 10.06.2024). Simon D., Borreguero A. M., de Lucas A., Rodriquez J. F. Recycling of polyurethanes from laboratory to industry, a journey towards the sustainability // Waste Management. 2018. Vol. 76. pp. 147-171. DOI: 10.1016/j.wasman.2018.03.041. Available at: https://www.sciencedirect.com/science/article/abs/pii/S0956053X18301831 (accessed 10.06.2024). Simon D., Borreguero A. M., de Lucas A., Rodriquez J. F. Recycling of polyurethanes from laboratory to industry, a journey towards the sustainability // Waste Management. 2018. Vol. 76. pp. 147-171. DOI: 10.1016/j.wasman.2018.03.041. Available at: https://www.sciencedirect.com/science/article/abs/pii/S0956053X18301831 (accessed 10.06.2024). Zhang X. B., Yao L., Qiu L. M., Gan Z. H., Yang R. P., Ma X. J., Liu Z. H. Experimental study on cryogenic moisture uptake in polyurethane foam insulation material // Cryogenics. 2004. Vol. 52. Issue 12. pp. 810-815. DOI: 10.1016/j.cryogenics.2012.10.001. Available at: https://www.sciencedirect.com/science/article/abs/pii/S0011227512001981 (accessed 10.06.2024). Zhang X. B., Yao L., Qiu L. M., Gan Z. H., Yang R. P., Ma X. J., Liu Z. H. Experimental study on cryogenic moisture uptake in polyurethane foam insulation material // Cryogenics. 2004. Vol. 52. Issue 12. pp. 810-815. DOI: 10.1016/j.cryogenics.2012.10.001. Available at: https://www.sciencedirect.com/science/article/abs/pii/S0011227512001981 (accessed 10.06.2024). Lee J.-R., Dhatal D. Review of flaws and damages in space launch vehicle: structures // Journal of Intelligent Material Systems and Structures. 2013. Vol. 24. Issue 1. pp. 4-20. DOI: 10.1177/1045389X12458041. Available at: https://journals.sagepub.com/doi/abs/10.1177/1045389X12458041 (accessed 10.06.2024). Lee J.-R., Dhatal D. Review of flaws and damages in space launch vehicle: structures // Journal of Intelligent Material Systems and Structures. 2013. Vol. 24. Issue 1. pp. 4-20. DOI: 10.1177/1045389X12458041. Available at: https://journals.sagepub.com/doi/abs/10.1177/1045389X12458041 (accessed 10.06.2024). Berardi U., Madzarevic J. Microstructural analysis and blowing agent concentration in aged polyurethane and polyisocyanurate foams // Applied Thermal Engineering. 2020. Vol. 164. 114440. DOI: 10.1016/j.applthermaleng.2019.114440. Available at: https://www.sciencedirect.com/science/article/abs/pii/S1359431119330455 (accessed 10.06.2024). Berardi U., Madzarevic J. Microstructural analysis and blowing agent concentration in aged polyurethane and polyisocyanurate foams // Applied Thermal Engineering. 2020. Vol. 164. 114440. DOI: 10.1016/j.applthermaleng.2019.114440. Available at: https://www.sciencedirect.com/science/article/abs/pii/S1359431119330455 (accessed 10.06.2024). Qian X., Liu Q., Zhang L., Li H., Liu J., Yan S. Synthesis of reactive DOPO-based flame retardant and its application in rigid polyisocyanurate-polyurethane foam // Polymer Degradation and Stability. 2022. Vol. 197. 109852. DOI: 10.1016/j.polymdegradstab.2022.109852. Available at: https://www.sciencedirect.com/science/article/abs/pii/S0141391022000386 (accessed 10.06.2024). Qian X., Liu Q., Zhang L., Li H., Liu J., Yan S. Synthesis of reactive DOPO-based flame retardant and its application in rigid polyisocyanurate-polyurethane foam // Polymer Degradation and Stability. 2022. Vol. 197. 109852. DOI: 10.1016/j.polymdegradstab.2022.109852. Available at: https://www.sciencedirect.com/science/article/abs/pii/S0141391022000386 (accessed 10.06.2024). Ball G. W., Haggis G.A., Hurd R., Wood J. F. A New Heat Resistant Rigid Foam // Journal of Cellular Plastics. 1968. Vol. 4. Issue 7. pp. 248-261. DOI: 10.1177/0021955X6800400703. Available at: https://journals.sagepub.com/doi/10.1177/0021955X6800400703?icid=int.sj-abstract.similar-articles.3 (accessed 10.06.2024). Ball G. W., Haggis G.A., Hurd R., Wood J. F. A New Heat Resistant Rigid Foam // Journal of Cellular Plastics. 1968. Vol. 4. Issue 7. pp. 248-261. DOI: 10.1177/0021955X6800400703. Available at: https://journals.sagepub.com/doi/10.1177/0021955X6800400703?icid=int.sj-abstract.similar-articles.3 (accessed 10.06.2024). Modesti M., Lorenzetti A. Flame retardancy of polyisocyanurate-polyurethane foams: use of different charring agents // Polymer Degradation and Stability. 2002. Vol. 78. Issue 2. pp. 341-347. DOI: 10.1016/S0141-3910(02)00184-2. Available at: https://www.sciencedirect.com/science/article/abs/pii/S0141391002001842 (accessed 10.06.2024). Modesti M., Lorenzetti A. Flame retardancy of polyisocyanurate-polyurethane foams: use of different charring agents // Polymer Degradation and Stability. 2002. Vol. 78. Issue 2. pp. 341-347. DOI: 10.1016/S0141-3910(02)00184-2. Available at: https://www.sciencedirect.com/science/article/abs/pii/S0141391002001842 (accessed 10.06.2024). Tsarfin M. Ya. Kataliticheskie sistemy na osnove alkogolyatov i karboksilatov chetvertichnogo ammonievogo osnovaniya dlya polucheniya izocianuratsoderzhashchih penoplastov [Catalytic systems based on alcoholates and carboxylates of quaternary ammonium base for the production of isocyanate-containing foams. Diss.] : dis. ... kand. him. nauk. Vladimir. 1990. 188 p. (in Russian). Tsarfin M. Ya. Kataliticheskie sistemy na osnove alkogolyatov i karboksilatov chetvertichnogo ammonievogo osnovaniya dlya polucheniya izocianuratsoderzhashchih penoplastov [Catalytic systems based on alcoholates and carboxylates of quaternary ammonium base for the production of isocyanate-containing foams. Diss.] : dis. ... kand. him. nauk. Vladimir. 1990. 188 p. (in Russian). Kresta J. E., Hsieh K. H. The Co-Catalytic Effect of Carbamate Groups in Cyclotrimerization of Isocyanates // Die Makromolekulare Chemie. 1978. Vol. 179. Issue 11. pp. 2779-2782. DOI: 10.1002/macp.1978.021791120. Available at: URL: https://onlinelibrary.wiley.com/doi/10.1002/macp.1979.021800429 (accessed 10.06.2024). Kresta J. E., Hsieh K. H. The Co-Catalytic Effect of Carbamate Groups in Cyclotrimerization of Isocyanates // Die Makromolekulare Chemie. 1978. Vol. 179. Issue 11. pp. 2779-2782. DOI: 10.1002/macp.1978.021791120. Available at: URL: https://onlinelibrary.wiley.com/doi/10.1002/macp.1979.021800429 (accessed 10.06.2024). Zhitinkina A.K., Shibanova N.A., Tarakanov O.G. Kinetics and Mechanism of the Catalytic Cyclotrimerisation and Polycyclotrimerisation of Isocyanates // Russian Chemical Review. 1985. Vol. 54 Issue 11. pp. 1104-1125. DOI: 10.1070/RC1985v054n11ABEH003160. Available at: https://doi.org/10.1070/rc1985v054n11abeh003160 (accessed 10.06.2024). Zhitinkina A.K., Shibanova N.A., Tarakanov O.G. Kinetics and Mechanism of the Catalytic Cyclotrimerisation and Polycyclotrimerisation of Isocyanates // Russian Chemical Review. 1985. Vol. 54 Issue 11. pp. 1104-1125. DOI: 10.1070/RC1985v054n11ABEH003160. Available at: https://doi.org/10.1070/rc1985v054n11abeh003160 (accessed 10.06.2024). Farkas A., Mills G. A. Catalytic Effects in Isocyanate Reactions // Advances in Catalysis. Farkas A., Mills G. A. Catalytic Effects in Isocyanate Reactions // Advances in Catalysis. Vol. 13. pp. 393 446. DOI: 10.1016/S0360-0564(08)60290-4. Available at: https://www.sciencedirect.com/science/article/abs/pii/S0360056408602904 (accessed 10.06.2024). Vol. 13. pp. 393 446. DOI: 10.1016/S0360-0564(08)60290-4. Available at: https://www.sciencedirect.com/science/article/abs/pii/S0360056408602904 (accessed 10.06.2024). 15. Dabi S., Zilkha A. Synergistic effect in the trimerization of isocyanates by organometallic catalysts // European Polymer Journal. 1980. Vol. 16. Issue 9. pp. 827-829. DOI: 10.1016/0014-3057(80)90111-1. Available at: https://www.sciencedirect.com/science/article/abs/pii/0014305780901111 (accessed 10.06.2024). 15. Dabi S., Zilkha A. Synergistic effect in the trimerization of isocyanates by organometallic catalysts // European Polymer Journal. 1980. Vol. 16. Issue 9. pp. 827-829. DOI: 10.1016/0014-3057(80)90111-1. Available at: https://www.sciencedirect.com/science/article/abs/pii/0014305780901111 (accessed 10.06.2024). Bechara I. Some Aspects of Innovative Catalysis of the Isocyanate Trimerization Reaction – Polyisocyanurate Foam Formation and Properties // Journal of Cellular Plastics. 1979. Vol. 15. Issue 2. pp. 102-113. DOI: 10.1177/0021955X7901500205. Available at: https://journals.sagepub.com/doi/10.1177/0021955X7901500205 (accessed 10.06.2024). Bechara I. Some Aspects of Innovative Catalysis of the Isocyanate Trimerization Reaction – Polyisocyanurate Foam Formation and Properties // Journal of Cellular Plastics. 1979. Vol. 15. Issue 2. pp. 102-113. DOI: 10.1177/0021955X7901500205. Available at: https://journals.sagepub.com/doi/10.1177/0021955X7901500205 (accessed 10.06.2024). Wakeshima I., Suzuki H., Kijima I. The Cyclic Trimerization of Isocyanates by Organic Tin (II) Compounds Containing Sn-O-C Bonds // Bulletin of the Chemical Society of Japan. 1975. Vol. 48. Issue 3. pp. 1069-1070. DOI: 10.1246/bcsj.48.1069. Available at: https://academic.oup.com/bcsj/article-abstract/48/3/1069/7354657 (accessed 10.06.2024). Wakeshima I., Suzuki H., Kijima I. The Cyclic Trimerization of Isocyanates by Organic Tin (II) Compounds Containing Sn-O-C Bonds // Bulletin of the Chemical Society of Japan. 1975. Vol. 48. Issue 3. pp. 1069-1070. DOI: 10.1246/bcsj.48.1069. Available at: https://academic.oup.com/bcsj/article-abstract/48/3/1069/7354657 (accessed 10.06.2024). Tiger R. P., Badayeva I. G., Bondarenko S. P., Entelis S. G. Kinetics and mechanism of cyclic trimerization of isocyanates using a tertiary amine-alkylene oxide catalytic system // Polymer Science U.S.S.R. 1977. Vol. 19. Issue 2. pp. 484-495. DOI: 10.1016/0032-3950(77)90098-3. Available at: https://www.sciencedirect.com/science/article/abs/pii/0032395077900983 (accessed 10.06.2024). Tiger R. P., Badayeva I. G., Bondarenko S. P., Entelis S. G. Kinetics and mechanism of cyclic trimerization of isocyanates using a tertiary amine-alkylene oxide catalytic system // Polymer Science U.S.S.R. 1977. Vol. 19. Issue 2. pp. 484-495. DOI: 10.1016/0032-3950(77)90098-3. Available at: https://www.sciencedirect.com/science/article/abs/pii/0032395077900983 (accessed 10.06.2024). Reymore H. E., Carleton P. S., Kolakowski R. A., Sayigh A. Isocyanurate Foams: Chemistry, Properties and Processing // Journal of Cellular Plastics. 1975. Vol. 11. Issue 6. pp. 328-344. DOI: 10.1177/0021955X7501100608. Available at: https://www.semanticscholar.org/paper/Isocyanu-rate-Foams%3A-Chemistry%2C-Properties-and-Reymore-Carleton/1e5214dc5fdb9732d067e204e0eb05cb7bdc65f3 (accessed 10.06.2024). Reymore H. E., Carleton P. S., Kolakowski R. A., Sayigh A. Isocyanurate Foams: Chemistry, Properties and Processing // Journal of Cellular Plastics. 1975. Vol. 11. Issue 6. pp. 328-344. DOI: 10.1177/0021955X7501100608. Available at: https://www.semanticscholar.org/paper/Isocyanu-rate-Foams%3A-Chemistry%2C-Properties-and-Reymore-Carleton/1e5214dc5fdb9732d067e204e0eb05cb7bdc65f3 (accessed 10.06.2024). Guo Y., Muuronen M., Deglmann P., Lucas F., Sijbesma R. P., Tomovic Z. Role of Acetate Anions in the Catalytic Formation of Isocyanurates from Aromatic Isocyanates // Journal of Organic Chemistry. 2021. Vol. 86. Issue 8. pp. 5651-5659. DOI: 10.1021/acs.joc.1c00119. Available at: https://pubs.acs.org/doi/10.1021/acs.joc.1c00119 (accessed 10.06.2024). Guo Y., Muuronen M., Deglmann P., Lucas F., Sijbesma R. P., Tomovic Z. Role of Acetate Anions in the Catalytic Formation of Isocyanurates from Aromatic Isocyanates // Journal of Organic Chemistry. 2021. Vol. 86. Issue 8. pp. 5651-5659. DOI: 10.1021/acs.joc.1c00119. Available at: https://pubs.acs.org/doi/10.1021/acs.joc.1c00119 (accessed 10.06.2024). Al Nabulsi A., Cozzula D., Hagen T., Leitner W., Muller T. E. Isocyanurate formation during rigid polyurethane foam assembly: a mechanistic study based on in-situ IR and NMR spectroscopy // Polymer Chemistry. 2018. Vol. 9. Issue 39. pp. 4891-4899. DOI: 10.1039/C8PY00637G. Available at: https://pubs.rsc.org/en/content/articlelanding/2018/py/c8py00637g (accessed 10.06.2024). Al Nabulsi A., Cozzula D., Hagen T., Leitner W., Muller T. E. Isocyanurate formation during rigid polyurethane foam assembly: a mechanistic study based on in-situ IR and NMR spectroscopy // Polymer Chemistry. 2018. Vol. 9. Issue 39. pp. 4891-4899. DOI: 10.1039/C8PY00637G. Available at: https://pubs.rsc.org/en/content/articlelanding/2018/py/c8py00637g (accessed 10.06.2024). Gibb J. N., Goodman J. M. The formation of high-purity isocyanurate through proazaphosphatrane-catalysed isocyanate cyclo-trimerisation: computational insights // Organic & Biomolecular Chemistry. 2013. Vol. 11. Issue 1. pp. 90-97. DOI: 10.1039/C2OB26547H. Available at: https://pubs.rsc.org/en/content/articlelanding/2013/ob/c2ob26547h (accessed 10.06.2024). Gibb J. N., Goodman J. M. The formation of high-purity isocyanurate through proazaphosphatrane-catalysed isocyanate cyclo-trimerisation: computational insights // Organic & Biomolecular Chemistry. 2013. Vol. 11. Issue 1. pp. 90-97. DOI: 10.1039/C2OB26547H. Available at: https://pubs.rsc.org/en/content/articlelanding/2013/ob/c2ob26547h (accessed 10.06.2024). Shashoua V. E., Sweeny W., Tietz R. F. The Homopolymerization of Monoisocyanates // Journal of the American Chemical Society. 1960. Vol. 82. Issue 4. pp. 866-873. DOI: 10.1021/JA01489A026. Available at: https://pubs.acs.org/doi/10.1021/ja01489a026 (accessed 10.06.2024). Shashoua V. E., Sweeny W., Tietz R. F. The Homopolymerization of Monoisocyanates // Journal of the American Chemical Society. 1960. Vol. 82. Issue 4. pp. 866-873. DOI: 10.1021/JA01489A026. Available at: https://pubs.acs.org/doi/10.1021/ja01489a026 (accessed 10.06.2024). Zharkov V. V., Vlasov R. R. A Quantitative Study of the Allophanate Formation Reaction in PIR Foams by FT-IR Spectroscopy // Journal of Cellular Plastics. 2022. Vol. 58. Issue 6. pp. 877-891. DOI: 10.1177/0021955X221141544. Available at: https://journals.sagepub.com/doi/full/10.1177/0021955X221141544 (accessed 10.06.2024). Zharkov V. V., Vlasov R. R. A Quantitative Study of the Allophanate Formation Reaction in PIR Foams by FT-IR Spectroscopy // Journal of Cellular Plastics. 2022. Vol. 58. Issue 6. pp. 877-891. DOI: 10.1177/0021955X221141544. Available at: https://journals.sagepub.com/doi/full/10.1177/0021955X221141544 (accessed 10.06.2024). Vlasov R. R., Ryabov S. A. Razrabotka metodiki kolichestvennogo opredeleniya osnovnyh vtorichnyh svyazej v poliuretan-poliizocianuratnyh penoplastah [Development of a methodology for the quantitative determination of the main secondary bonds in polyurethane-polyisocyanurate foams] // XXIV Mezhdunarodnaya nauchno-prakticheskaya konferenciya studentov i molodyh uchenyh «Himiya i himicheskaya tekhnologiya v XXI veke» [XXIV International Scientific and Practical Conference of Students and young Scientists "Chemistry and chemical technology in the XXI century"]. Tomsk: Izd-vo Tomskogo politekhnicheskogo universiteta. 2023. Volume 1. pp. 378-379. (in Russian). Vlasov R. R., Ryabov S. A. Razrabotka metodiki kolichestvennogo opredeleniya osnovnyh vtorichnyh svyazej v poliuretan-poliizocianuratnyh penoplastah [Development of a methodology for the quantitative determination of the main secondary bonds in polyurethane-polyisocyanurate foams] // XXIV Mezhdunarodnaya nauchno-prakticheskaya konferenciya studentov i molodyh uchenyh «Himiya i himicheskaya tekhnologiya v XXI veke» [XXIV International Scientific and Practical Conference of Students and young Scientists "Chemistry and chemical technology in the XXI century"]. Tomsk: Izd-vo Tomskogo politekhnicheskogo universiteta. 2023. Volume 1. pp. 378-379. (in Russian). Buist J. M., H. Gudgeon. Advances in Polyurethane Technology. London: Maclaren and Sons LTD, 1968. 311 p. Buist J. M., H. Gudgeon. Advances in Polyurethane Technology. London: Maclaren and Sons LTD, 1968. 311 p. Von Merten R. Lauerer D., Braun G., Dahm M. Über den Aufbau von Polyurethan-Kunststoffen. II. Die Struktur von Polyurethan-Shaumstoffen in Abhangigkeit von der Temreratur, der Zeit und der Rezeptur; IR-spektroskopische Nachweisgrenzen fur Urethan- und Harnstoffgruppen in Polymeren // Die Markomolekulare Chemie. 1967. Vol. 101. Issue 1. pp. 337-366. Von Merten R. Lauerer D., Braun G., Dahm M. Über den Aufbau von Polyurethan-Kunststoffen. II. Die Struktur von Polyurethan-Shaumstoffen in Abhangigkeit von der Temreratur, der Zeit und der Rezeptur; IR-spektroskopische Nachweisgrenzen fur Urethan- und Harnstoffgruppen in Polymeren // Die Markomolekulare Chemie. 1967. Vol. 101. Issue 1. pp. 337-366. Campbell T. W., Monagle J. J., Foldi V. S. Carbodiimides. I. Conversion of Isocyanates to Carbodiimides with Phospholine Oxide Catalyst // Journal of the American Chemical Society. 1962. Vol. 84. Issue 19. pp. 3673-3677. DOI: 10.1021/ja00878a015. Available at: https://pubs.acs.org/doi/10.1021/ja00878a015 (accessed 10.06.2024). Campbell T. W., Monagle J. J., Foldi V. S. Carbodiimides. I. Conversion of Isocyanates to Carbodiimides with Phospholine Oxide Catalyst // Journal of the American Chemical Society. 1962. Vol. 84. Issue 19. pp. 3673-3677. DOI: 10.1021/ja00878a015. Available at: https://pubs.acs.org/doi/10.1021/ja00878a015 (accessed 10.06.2024). Bhattacharjee D., Engineer R. An Improved Technique for the Determination of Isocyanurate and Isocyanate Conversion by Photoacoustic FTIR // Journal of Cellular Plastics. 1996. V. 32. Issue 3. pp. 260-273. DOI: 10.1177/0021955X9603200304. Available at: https://journals.sagepub.com/doi/10.1177/0021955X9603200304 (accessed 10.06.2024). Bhattacharjee D., Engineer R. An Improved Technique for the Determination of Isocyanurate and Isocyanate Conversion by Photoacoustic FTIR // Journal of Cellular Plastics. 1996. V. 32. Issue 3. pp. 260-273. DOI: 10.1177/0021955X9603200304. Available at: https://journals.sagepub.com/doi/10.1177/0021955X9603200304 (accessed 10.06.2024). Modesti M. Lorenzetti A. An experimental method for evaluating isocyanate conversion and trimer formation in polyisocyanurate-polyurethane foams // European Polymer Journal. 2001. Vol. 37. Issue 5. pp. 949-954. DOI: 10.1016/S0014-3057(00)00209-3. Available at: Available at: https://www.sciencedirect.com/science/article/abs/pii/S0014305700002093 (accessed 10.06.2024). Modesti M. Lorenzetti A. An experimental method for evaluating isocyanate conversion and trimer formation in polyisocyanurate-polyurethane foams // European Polymer Journal. 2001. Vol. 37. Issue 5. pp. 949-954. DOI: 10.1016/S0014-3057(00)00209-3. Available at: Available at: https://www.sciencedirect.com/science/article/abs/pii/S0014305700002093 (accessed 10.06.2024). Raffel B., Lovenich C. J. High Throughput Screening of Rigid Polyisocyanurate Foam Formulations: Quantitative Characterization of Isocyanurate Yield via the Adiabatic Temperature Method // Journal of Cellular Plastics. 2006. Vol. 42. Issue 1. pp. 17-47. DOI: 10.1177/0021955X06060943. Available at: https://journals.sagepub.com/doi/10.1177/0021955X06060943 (accessed 10.06.2024). Raffel B., Lovenich C. J. High Throughput Screening of Rigid Polyisocyanurate Foam Formulations: Quantitative Characterization of Isocyanurate Yield via the Adiabatic Temperature Method // Journal of Cellular Plastics. 2006. Vol. 42. Issue 1. pp. 17-47. DOI: 10.1177/0021955X06060943. Available at: https://journals.sagepub.com/doi/10.1177/0021955X06060943 (accessed 10.06.2024). Lovenich C. J., Raffel B. A Quantitative Investigation of the Effect of the Recipe on the Trimer-yield in Polyisocyanurate Foams // Journal of Cellular Plastics. 2006. Vol. 42. Issue 4. pp. 289-305. DOI: 10.1177/0021955X06063515. Available at: https://journals.sagepub.com/doi/10.1177/0021955X06063515 (accessed 10.06.2024). Lovenich C. J., Raffel B. A Quantitative Investigation of the Effect of the Recipe on the Trimer-yield in Polyisocyanurate Foams // Journal of Cellular Plastics. 2006. Vol. 42. Issue 4. pp. 289-305. DOI: 10.1177/0021955X06063515. Available at: https://journals.sagepub.com/doi/10.1177/0021955X06063515 (accessed 10.06.2024). Li J. P., Ren F. J., Li L. H., Yan Y. Study on the Capability of Trimerization Catalyst in PIR-PU Foam // Plastic Additives. 2014. Issue 6. pp. 49-53. Li J. P., Ren F. J., Li L. H., Yan Y. Study on the Capability of Trimerization Catalyst in PIR-PU Foam // Plastic Additives. 2014. Issue 6. pp. 49-53. Dick C., Dominguez-Rosado E., Eling B., Liggat J. J., Lindsay C. I., Martin S. C., Mohammed M. H., Seeley G., Snape S. E. The flammability of urethane-modified polyisocyanurates and its relationship to thermal degradation chemistry // Polymer. 2001. Vol. 42. pp. 913-923. DOI: 10.1016/S0032-3861(00)00470-5. Available at: https://www.sciencedirect.com/science/article/abs/pii/S0032386100004705 (accessed 10.06.2024). Dick C., Dominguez-Rosado E., Eling B., Liggat J. J., Lindsay C. I., Martin S. C., Mohammed M. H., Seeley G., Snape S. E. The flammability of urethane-modified polyisocyanurates and its relationship to thermal degradation chemistry // Polymer. 2001. Vol. 42. pp. 913-923. DOI: 10.1016/S0032-3861(00)00470-5. Available at: https://www.sciencedirect.com/science/article/abs/pii/S0032386100004705 (accessed 10.06.2024). Clift S. M., Grimminger J., Muha K. New Polyisocyanurate Catalysts for Rigid Polyurethane Foams // Proceedings of SPI 35th Annual Polyurethane Technical/Marketing Conference. Boston. 1994. pp. 1-22. Clift S. M., Grimminger J., Muha K. New Polyisocyanurate Catalysts for Rigid Polyurethane Foams // Proceedings of SPI 35th Annual Polyurethane Technical/Marketing Conference. Boston. 1994. pp. 1-22.