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How wood adhesives work and where are the areas for improvementAuthor(s): Charles R. Frihart
Source: In: International Conference on Wood Adhesives 2013, October 9-11, 2013 from CD ISBN: 978-0-935018-37-0. 2013; pp. 50-63.
Publication Series: Full Proceedings
Station: Forest Products Laboratory
PDF: Download Publication (485.99 KB)
DescriptionInvoking normal adhesion theory, bonding of wood would seem to be easy in that the surface has plenty of roughness for mechanical interlocking with high enough surface energy, there is an abundance of hydroxyl groups on the wood for hydrogen bonding to the adhesives, and the aqueous solvent in the adhesive can readily soak into the wood. In fact most adhesives will form good to excellent bonds to wood as long as the bond is kept dry. However, because wood swells and shrinks with changes in ambient relative humidity, most bonded wood products must pass some type of moisture exposure test. Performance criteria eliminates many adhesives because the wood is swelling at the same time that the adhesive is being plasticized by the water, resulting in weak bondlines. Other adhesives can be too brittle to adjust to the dimensional changes of the wood leading to cracks that eventually cause macroscopic fractures. Thus, having enough moisture resistance for bonded assemblies continues to be a challenge. Other challenges include dealing with the variation and changes in the wood supply, addressing application and curing issues, dealing with lower formaldehyde emission standards, bonding new types of wood products and keeping wood competitive with non-wood products.
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CitationFrihart, Charles R. 2013. How wood adhesives work and where are the areas for improvement. In: International Conference on Wood Adhesives 2013. Toronto, Ontario, Canada. October 9-11, 2013 from CD ISBN: 978-0-935018-37-0. 2013; pp. 50-63.
Keywordswood adhesives, moisture durability, adhesive classes, improved products, environmental
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