Characterization of Hydrolytic Degradation of U-f Joints Through Apparent Diffusivity
Keywords:Urea-formaldehyde, hydrolysis, aging, diffusivity, chemical degradation, mechanical degradation
The hydrolytic aging of an adhesive joint (wood-urea/formaldehyde resin) is characterized by measurements of the apparent diffusivity of two inert gases within the bond. This kind of measurement is of some interest, because it includes both chemical and geometrical changes in joint structure.
Apparent diffusivities are determined in a diffusion cell after various degradation times in a cold water bath. Our results show that diffusivity increases with aging time with an asymptotic trend. Nevertheless, when the joint undergoes cyclic aging (immersion/drying), chemical degradation occurs mainly during the first cycle, while mechanical degradation observed during the drying steps also appears during the following cycles. The values of apparent diffusivity show that the solute transport is a real diffusional transport phenomenon and that resin joints are not porous.
Cahn. 1991. Cahn Dca Applications Software. ATI Analytical Technology Inc., Madison, WI.nDorris, G. M., and D. G. Gray. 1978. The surface analysis of paper and wood fibers by ESCA (Electron Spectroscopy for Chemical Analysis). I. Application to cellulose and lignin. Cellulose Chem. Technol. 12:9-23.nEtzler, F. M., and J. J. Conners. 1995. The surface chemistry of paper: Its relationship to printability and other paper technologies. In T. E. Conners and S. Banergee, eds. Surface analysis of paper. CRC Press, Boca Raton, FL.nFowkes, F. M. 1972. Donor-acceptor interactions at interfaces. J. Adhesion 4:155-159.nGardner, D. J., N. C. Generalla, D. W. Gunnells, and M. P. Wolcott. 1991. Dynamic wettability of wood. Langmuir 7(11):2498-2502.nGardner, D., M. P. Wolcott, L. Wilson, Y. Huang, and M. Carpenter. 1996. Our understanding of wood chemistry in 1995. Pages 29-36 in Proc. No. 7296 1995 Wood Adhesive Symposium, Forest Products Society.nGirifalco, L. A., and R. J. Good. 1957. A theory for the estimation of surface and interfacial energies. I. Derivation and application to interfacial tension. J. Phys. Chem. 61:904.nGunnells, D. W. 1992. Utilizing DCA analysis to investigate the effects of environmental conditions on the surface of wood. Master's thesis, West Virginia University, Morgantown, WV.nHanley, S. J., and D. G. Gray. 1994. Atomic force microscope images of black spruce wood sections and pulp fibers. Holzforschung 48:29-34.nKamdem, D. P., S. K. Bose, and P. Luner. 1993. Inverse gas chromatography characterization of birch wood meal. Langmuir 9(11):3039-3044.nLiptakova, E., and J. Kudela. 1994. Analysis of the wood-wetting process. Holzforschung 48:139-144.nLiu, F. P., D. J. Gardner, and M. P. Wolcott. 1995. A model for the description of polymer surface dynamic behavior. I. Contact angle vs. polymer surface properties. Langmuir 11(7):2674-2681.nMarch, J. 1977. Advanced organic chemistry reactions, mechanisms, and structure. 2nd ed. McGraw Hill Book Co., New York, NY. P. 238.nMoore, W. E., and D. B. Johnson. 1985. Procedures for chemical analysis of wood and wood products. USDA Forest Serv. Forest Prod. Lab., Madison, WI.nNguyen, T., and W.E. Johns. 1978. Polar and dispersion force contributions to the total surface free energy of wood. Wood Sci. Technol. 12:63-74.nRowe, J.W., and A.H. Conner. 1979. Extractives in eastern hardwoods—A review. USDA Forest Serv. Gen. Tech. Rep. FPL-18. USDA Forest Prod. Lab., Madison, WI.nVan Oss, C. J., M. K. Chaudhury, and R. J. Good. 1987. Monopolar surfaces. Adv. Colloid Interface Sci. 28:35-64.nVan Oss, C. J., M. K. Chaudhury, and R. J. Good. 1988. Interfacial Lifshitz-van der Waals and polar interactions in macroscopic systems. Chem. Rev. 88:927-941.nWu, S. 1971. Calculation of interfacial tension in polymer systems. J. Polymer Sci. Part C 34:19-30.nWu, W., R. F. Giese Jr., and C. J. van Oss. 1995. Evaluation of the Lifshitz-van der Waals/acid-base approach to determine surface tension components. Langmuir 11(1):379-382.nZisman, W. A. 1964. Relation to equilibrium contact angle to liquid and solid constitution. Pages 1-51 in F. W. Fowkes, ed. American Chemical Society Adv. in Chem. 43:1-51.nZisman, W. A. 1977. Influence of constitution on adhesion. Pages 33-66 in Irving Skeist, ed. Handbook of adhesives, 2nd ed. Van Nostrand Reinhold Co., New York, NY.n
The copyright of an article published in Wood and Fiber Science is transferred to the Society of Wood Science and Technology (for U. S. Government employees: to the extent transferable), effective if and when the article is accepted for publication. This transfer grants the Society of Wood Science and Technology permission to republish all or any part of the article in any form, e.g., reprints for sale, microfiche, proceedings, etc. However, the authors reserve the following as set forth in the Copyright Law:
1. All proprietary rights other than copyright, such as patent rights.
2. The right to grant or refuse permission to third parties to republish all or part of the article or translations thereof. In the case of whole articles, such third parties must obtain Society of Wood Science and Technology written permission as well. However, the Society may grant rights with respect to Journal issues as a whole.
3. The right to use all or part of this article in future works of their own, such as lectures, press releases, reviews, text books, or reprint books.