Polyurethane prepolymers prepared from toluene 2,4-diisocyanate, toluene 2,6-diisocyanate, and polypropylene glycol with a ratio between the isocyanate and hydroxyl groups equal to 2 were analyzed by 1 H nuclear magnetic resonance (NMR) spectroscopy in acetone-d 6 . Different temperatures and concentrations were used. Toluene 2,4-dimethylurethane and toluene 2,6-dimethylurethane were synthesized and used as model compounds to assign prepolymers signals. Measurements of spin-lattice relaxation time T 1 by "inversion recovery" experiments were carried out on toluene 2,4-diisocyanate, toluene 2,6-diisocyanate, toluene 2,4-dimethylurethane, toluene 2,6-dimethylurethane, and polyurethane prepolymers. Differences in T 1 times were used to interpret prepolymers spectra, by means of the strong observed effect on protons due to the presence of adjacent isocyanate groups.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.