Solid-state NMR Analysis of Adhesive Bondlines in Pilot Scale Flakeboards


  • Robert G. Schmidt
  • Charles E. Frazier


Adhesion, phenol-formaldehyde, solid-state NMR, isotopic labeling


This work demonstrates the application of solid-state NMR to the analysis of adhesive bondlines in pilot scale flakeboards. A comparison to laboratory scale experiments is also made. Phenol-formaldehyde resin is easily detected by using labeled formaldehyde. However, resin washout can occasionally prevent detection in pilot scale composites. The relative degree of resin cure is determined by measuring corrected signal areas and also by measuring proton longitudinal relaxation in the rotating frame. Such relaxation measurements were effective in laboratory scale experiments, but were much less useful for pilot scale tests. The degree of phenol-formaldehyde polymerization was not affected by changes in wood furnish moisture content; the range of furnish moisture was 13 and 24%. This suggests that phenol-formaldehyde moisture intolerance is not related to polymerization retardation by water. This work demonstrates the feasibility of performing detailed bondline analyses on pilot and possibly industrial scale composites.


Fyfe, C. A. 1983. Solid state NMR for chemists. CFC Press, Guelph, Ontario, Canada.nHalevi, E. A. 1963. Secondary isotope effects. Pages 109-222 in S. G. Cohen, A. Streitwieser, Jr., and R. W. Taft, eds. Progress in physical organic chemistry. Interscience Publishers, New York, NY.nMarcinko, J. L., S. Devathala, P. L. Rinaldi, and S. Bao. 1998. Investigating the molecular and bulk dynamics of PMDI/wood and UF/wood composites. Forest Prod. J. 48(6):81-84.nMarcinko, J. L., P. L. Rinaldi, and S. Bao. 1999. Exploring the physicochemical nature of PMDI/wood structural composite adhesion. Forest Prod. J. 49(5):75-78.nMehring, M. 1983. High resolution NMR spectroscopy in solids. 2nd ed. Springer-Verlag, Berlin, Germany.nNi, J., and C. E. Frazier. 1998. 15N CP/MAS NMR study of the isocyanate/wood adhesive bondline, effects of structural isomerism. J. Adhesion 66:89-116.nParmer, J. F., L. C. Dickinson, J. C. W. Chien, and R. S. Porter. 1987. Polymer-polymer miscibility determination via CP/MAS NMR in blends of deuterated and protonated polymers. Macromolecules 20:2308-2310.nSchmidt, R. G. 1998. Aspects of wood adhesion: Application of 13C CP/MAS NMR and fracture testing. Ph.D. dissertation, Virginia Polytechnic Institute & State University. Ch. 6:79-95.'>, R. G., and C. E. Frazier. 1998. 13C CP/MAS NMR as a direct probe of the wood-phenol formaldehyde adhesive bondline. Wood Fiber Sci. 30(3):250-258.nSchmidt, R. G., M.-P. Laborie, and C. E. Frazier. 2000. Labscale synthesis of isotopically labeled formaldehyde for the production of formaldehyde-based wood adhesives. Holzforschung 54(1):98-100.nShiner, V. J., Jr. 1970. Deuterium isotope effects in solvolytic substitution at saturated carbon. Pages 90-155 in C. J. Collins and N. S. Bowman, eds. Isotope effects in chemical reactions. ACS Monograph, Van Nostrand Reinhold, New York, NY.nVan Hook, W. A. 1970. Kinetic isotope effects: Introduction and discussion of theory. Pages 1-84 in C. J. Collins and N. S. Bowman, eds. Isotope effects in chemical reactions. ACS Monograph, Van Nostrand Reinhold, New York, NY.nWerstler, D. D. 1986. Quantitative 13C n.m.r. characterization of aqueous formaldehyde resins: 1. phenol-formaldehyde resins. Polymer 27:750-756.n






Research Contributions