Kinetic and thermodynamic analysis of the polymerization of polyurethanes by a rheological method

Graphical abstract: - Highlights: • Kinetic and thermodynamic analysis for the formation of a functional polyurethane (PU) has been carried out. • Rheological parameters were used to obtain the profile of the resin's curing degree. • Kamal-Sourour autocatalytic kinetic model describes well this polyaddition reaction. • A deeper understanding of the mechanism of PU systems has been achieved. • This metallo-PU finds its application in the chemistry of advanced energetic materials. - Abstract: As part of an investigation into the mechanism and chemorheology of linear segmented polyurethane (PU) systems, this paper presents the kinetic and thermodynamic characterization of the reaction between an advanced functional metallo-polyol derivative of hydroxyl-terminated polybutadiene (HTPB), (ferrocenylbutyl)dimethylsilane grafted HTPB, and isophorone diisocyanate (IPDI). The evolution of viscoelastic properties, such as the storage modulus (G′), was recorded in bulk under isothermal conditions at four different temperatures between 50 and 80 °C, and a resin curing degree profile was obtained for this elastic modulus. The use of the Kamal-Sourour autocatalytic kinetic model was proposed, describing the overall curing process perfectly. All the kinetic and thermodynamic parameters, including reaction orders, kinetic constants and activation energy, were determined for the polyaddition reaction under study. A relevant autocatalysis effect, promoted by the urethane group, has been found. The isoconversion method was also used to analyze the variation of the global activation energy with conversion. The global activation energy increases slightly as the curing reaction proceeds with a maximum value reached at approximately 30% conversion. In addition, the Eyring parameters were calculated from the obtained kinetic data.