In-situ characterization of the cure reaction of HTPB and IPDI by simultaneous NMR and IR measurements

Abstract

The progress of the cure reaction of hydroxyl-terminated (poly)butadiene (HTPB) and isophorone diisocyanate (IPDI) to a polyurethane is of major importance for the adjustment of process parameters as well as final product properties. Simultaneous low field nuclear magnetic resonance relaxometry and near infrared spectroscopy are applied in-situ to study the progress of the cure reaction with respect to time. The sensitive spots of both methods are coincident, allowing quantitative comparison of the results of both methods, as the same region of the sample is examined. The aim is to get a more comprehensive insight into the reaction by the combination of the two analytical methods. Molecular dynamics as provided by NMR relaxation data and chemical concentration information via near infrared spectroscopy allow detailed monitoring and deeper insight into the complex reaction.