Non-isothermal DSC and rheological curing of ferrocene-functionalized, hydroxyl-terminated polybutadiene polyurethane

The curing reaction of a novel linear segmented polyurethane (PU) based on a functional metallo-polyol derivative of hydroxyl-terminated polybutadiene (HTPB), (ferrocenylbutyl)dimethylsilane-grafted HTPB, and isophorone diisocyanate (IPDI) is studied under non-isothermal conditions. This reaction is of particular interest in advanced composite energetic materials for the aeronautic technology. Differential scanning calorimetry (DSC) indicates that the curing mechanism involves multiple reactions, which was further substantiated by a rheological analysis. Rheometry was used to analyse the chemorheological behaviour through the evolution of both complex viscosity (η⁎) and storage modulus (Gʹ) at four different heating rates. The profiles obtained for the viscosity were applied to four- and six-parameter Arrhenius models. The curves of rheological conversion degree were also obtained from the elastic modulus data, and values for the activation energy of this polyaddition reaction were estimated by the application of Kissinger's method.