Chemical structure investigations of polyurethane binders based on difunctional linear glycidyl azide polymer (GAP) cured with isophorone diisocyanate (IPDI) were performed using C-13-NMR spectroscopy in solution. Chemical functions such as urethane, urea, allophanate, and biuret were all expected to be detected in these polymeric binders. C-13-NMR assignment of the C=O urethane and urea functions were found in these polymers as determined by using model compounds of IPDI. The C-13-NMR data gathered in this article can be considered as basic parameters for further characterization of polyurethane structure based on IPDI. Also, C-13 CP MAS NMR spectra of GAP-IPDI-based polymers were carried out to identify the various chemical functions present in solid polyurethane elastomer. In addition, the curing evolution of a GAP-IPDI-based polymer at 50 and 80 degrees C in bulk was monitored, and the reaction path of the binder was readily determined. Some conclusions on the effects of the cure catalyst and the curing temperature were also drawn.