Understanding Wood Bonds–Going Beyond What Meets the Eye: a Critical Review
Understanding Wood Bonds–Going Beyond What Meets the Eye: A Critical Review Christopher G. Hunt1*, Charles R. Frihart1, Manfred Dunky2 and Anti Rohumaa3 1Forest Products Laboratory, Madison, Wisconsin, USA 2Kronospan GmbH Lampertswalde, Lampertswalde, Germany 3FibreLaboratory, South-Eastern Finland University of Applied Sciences (XAMK), Savonlinna, Finland Abstract: Understanding why wood bonds fail is an excellent route toward understanding how to make them better. Certifying a bonded product usually requires achieving a specifc load, percent wood failure, and an ability to withstand some form of moisture exposure without excessive delamination. While these tests protect the public from catastrophic failures, they are not very helpful in understanding why bonds fail. Understanding failure often requires going beyond what meets the naked eye, conducting additional tests, probing the wood surface, the fracture surface, adhesive properties, and the interaction of wood and adhesive during bond formation and service. This review of wood bond analysis methods reviews fundamentals of wood bonding and highlights recent developments in the analyses and understanding of wood bonds. It concludes with a series of challenges facing the wood bonding community. Keywords: Wood adhesive, wood bond, microscopy, penetration, failure List of Abbreviations AFM Atomic Force Microscopy AP Average Penetration CLSM Confocal Laser Scanning Microscopy CV Collapsed Vessel CWBL Chemical Weak Boundary Layer DCB Dual Cantilever Beam DIC Digital Image Correlation DMA
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