d5dc493e414043c788908e5875f7290320260412042135968depositorname@domain.comregistrantJournal of Aerospace Technology and ManagementJ. Aerosp. Technol. Manag.2175-9146202416Christiane BuenoDall’AgnolDepartamento de Ciência e Tecnologia Aeroespacial, Brazil; Instituto Tecnológico de Aeronáutica, Brazil; Instituto de Aeronáutica e Espaço, Brazilhttp://orcid.org/0009-0001-2768-5498Rita de Cássia LazzariniDutraDepartamento de Ciência e Tecnologia Aeroespacial, Brazil; Instituto Tecnológico de Aeronáutica, Brazilhttp://orcid.org/0000-0001-9958-1279Milton FariaDinizInstituto de Aeronáutica e Espaço, Brazilhttp://orcid.org/0000-0003-0246-0660Lucas SousaMadureiraInstituto de Aeronáutica e Espaço, Brazilhttp://orcid.org/0000-0001-7190-323XSilvana NavarroCassuDepartamento de Ciência e Tecnologia Aeroespacial, Brazil; Instituto Tecnológico de Aeronáutica, Brazil; Instituto de Aeronáutica e Espaço, Brazilhttp://orcid.org/0000-0002-6978-0266ABSTRACT Polymers based on glycidyl azide polymer (GAP) and isocyanate present molecular structures dependent on NCO/OH molar ratio and diisocyanate reactivity. In this study, GAP polymers are obtained from a reaction with aromatic (toluene diisocyanate, TDI) or aliphatic (isophoranediisocyanate, IPDI) diisocyanates, varying the NCO/OH molar ratio from equimolar to 2.5. The increment in NCO/OH molar ratio increases the gel fraction in GAP/TDI polymers up to 90 wt%, along with a progressive growth in their glass transition temperature (Tg), which rises 10 °C from NCO/OH equimolar to 2.5. In opposition, in the GAP/IPDI polymers, the maximum gel fraction is 20 wt%, and the Tg value practically does not change in NCO excess. Infrared spectroscopy shows the predominant presence of urethane groups in polymers containing up to 2.0 NCO/OH molar ratio; however, at 2.5, urethane and allophanate characteristic bands are present in both polymers. That reactivity is controlled by chemical kinetics since the activation barrier of the reaction between the GAP and TDI is 10 kcal.mol-1 lower than in the corresponding reaction with the IPDI. 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