We have used infrared spectroscopy to study the reaction between phenyl isocyanate and glucose, cellulose, lignin, and wood. In the latter instance we have investigated oven-dried wood, wood at its fiber saturation point, and wood at 19% and 7% moisture levels. Our results show that
the isocyanate reacts with all these entities, but that its reaction with water is quicker than with any of the other hydroxyl-containing compounds, and when water is present the water-isocyanate reaction dominates all others. Lignin was found to react more readily than any of the sugar derivatives.
In oven-dried wood, the presence of strong new absorptions at 1712 and 1694 cm-1 (indicative of a carbamate group) is evidence of a direct chemical bond between the isocyanate and the wood polymer structure. We have also studied the reaction between 4,4'-diphenylmethane diisocyanate
(MDI)—a commercially used adhesive—with wood flour at various levels of moisture content (MC), and the infrared spectra again support the presence of a wood-isocyanate bond for oven-dried wood and for wood at 7% moisture content. For wood at higher moisture content levels, our
infrared results suggest that the isocyanate reacts with the water in preference to the wood polymers.
Department of Chemistry, Brigham Young University, Provo, Utah 84602
Publication date: February 1, 1995
More about this publication?
The Society publishes the internationally recognized, peer reviewed journal, Applied Spectroscopy, which is available both in print and online. Subscriptions are included with membership or can be purchased by institutional or corporate organizations. Abstracts may be viewed free of charge. Previously published as Bulletin (Society for Applied Spectroscopy)